indico.ph.ed.ac.uk€¦ · Building-Up the Grassmannian Correspondence: On-Shell Varieties The...

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Building-Up the Grassmannian Correspondence: On-Shell Varieties The Classification of On-Shell (Cluster) Varieties More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM Jacob L. Bourjaily Niels Bohr Institute based on work in collaboration with S. Franco, D. Galloni, and C. Wen; E. Herrmann, C. Langer, A. McLeod, and J. Trnka; N. Arkani-Hamed, F. Cachazo, A. Goncharov, A. Postnikov, and J. Trnka [arXiv:1911.09106] [arXiv:1909.09131] [arXiv:1608.00006] [arXiv:1412.8475] [arXiv:1212.5605] 3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

Transcript of indico.ph.ed.ac.uk€¦ · Building-Up the Grassmannian Correspondence: On-Shell Varieties The...

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Jacob L. BourjailyNiels Bohr Institute

    based on work in collaboration with

    S. Franco, D. Galloni, and C. Wen;

    E. Herrmann, C. Langer, A. McLeod, and J. Trnka;

    N. Arkani-Hamed, F. Cachazo, A. Goncharov, A. Postnikov, and J. Trnka

    [arXiv:1911.09106] [arXiv:1909.09131] [arXiv:1608.00006] [arXiv:1412.8475] [arXiv:1212.5605]

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    Enormous Advances in Understanding Scattering Amplitudes

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv

    ≡∫

    ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv

    ≡∫

    ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv

    ≡∫

    ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    ≡ ()

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics

    • on-shell diagrams– bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    ⇔Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    ⇔Grassmannian Geometry

    •{strata C∈G(k, n), volume-form ΩC

    }– cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar• physical symmetries

    – trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms

    – cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries

    – trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms

    – cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms

    – cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored

    , undirected, planar

    bi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored

    , undirected, planarbi-colored

    , directed

    , planar

    bi-colored

    , undirected

    , non-planar

    bi-colored

    , directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected

    , planarbi-colored, directed

    , planar

    bi-colored, undirected

    , non-planar

    bi-colored, directed

    , non-planar

    bi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    positroid variety

    ,(∏

    idαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?),(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    positroid variety ,(∏

    idαiαi

    )

    ×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    positroid variety ,(∏

    idαiαi

    )

    ×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    positroid variety ,(∏

    idαiαi

    )

    ×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries: the Yangian– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    positroid variety ,(∏

    idαiαi

    )

    ×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N=4• on-shell diagrams

    – bi-colored, undirected, planar

    bi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries: the Yangian– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    positroid variety ,(∏

    idαiαi

    )

    ×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C

    1 α8 α5+α8α14 α5α11 0 0 0 0 00 0 0 1 α10α4+α10α13 α4α7 0 0α3α9 0 0 0 0 0 1 α6 α3+α6α12α9 0 α1 α1α11 0 α1α2 α1α2α7 0 1

    ΩC ≡(dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: planar N

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: non-planar N=4• on-shell diagrams

    bi-colored, undirected, planarbi-colored, directed , planar

    bi-colored, undirected, non-planar

    bi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries: ?– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: non-planar N=4• on-shell diagrams

    bi-colored, undirected, planarbi-colored, directed , planar

    bi-colored, undirected, non-planar

    bi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries: ?– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: non-planar N=4• on-shell diagrams

    bi-colored, undirected, planarbi-colored, directed , planar

    bi-colored, undirected, non-planar

    bi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries: ?– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }–

    cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )

    ×JN– 4

    cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )

    ×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: non-planar N

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics: non-planar N

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored, undirected, planarbi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )×(1+α2α4α13(α8+α7α12)

    )N– 4

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions

    (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored, undirected, planarbi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )×(1+α2α4α13(α8+α7α12)

    )N– 4

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions (for math and physics)

    • how many functions exist?

    (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored, undirected, planarbi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )×(1+α2α4α13(α8+α7α12)

    )N– 4

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions (for math and physics)

    • how many functions exist?

    (how to name them?)• what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored, undirected, planarbi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )×(1+α2α4α13(α8+α7α12)

    )N– 4

    3/3/2020 Cluster Algebras & Geometry of Amplitudes Higgs Centre Stratifying On-Shell (Cluster) Varieties

  • Building-Up the Grassmannian Correspondence: On-Shell VarietiesThe Classification of On-Shell (Cluster) Varieties

    More to Explore: ‘Color-Dressed’ On-Shell Functions in sYM

    On-Shell Physics/Grassmannian Geometry Correspondence

    fΓ≡∏

    i

    (∑hi,qi

    ∫d3LIPSi

    )∏vAv ≡

    ∫ΩC δ(C, p, h)

    Important Open Questions (for math and physics)

    • how many functions exist? (how to name them?)

    • what (functional) relations do they satisfy?• what are their (infinite-dimensional) symmetries?

    – do these extend to entire amplitudes?• what changes with (Lie-algebra) ‘coloring’?

    On-Shell Physics• on-shell diagrams

    – bi-colored, undirected, planarbi-colored, directed , planarbi-colored, undirected, non-planarbi-colored, directed , non-planarbi-colored, undirected, non-planar

    • physical symmetries– trivial symmetries (identities)

    ⇔Grassmannian Geometry•{strata C∈G(k, n), volume-form ΩC

    }

    – cluster(?) variety

    (?)

    ,(∏

    idαiαi

    )×JN– 4positroid variety ,

    (∏i

    dαiαi

    )×JN– 4cluster variety(?)

    (?)

    ,(∏

    idαiαi

    )×JN– 4

    • volume-preserving diffeomorphisms– cluster coordinate mutations, . . .

    C⊥≡

    α1 1 0 α2 0 0 0 0 00 0 α3 1 0 α4 0 0 00 0 0 α5 1 α6 0 0 00 0 0 0 0 1 0 α7 α80 0 0 0 0 α9 1 α10 0α11 0 0 0 0 0 0 1 α120 α13 α14 0 0 0 0 0 1

    ΩC ≡

    (dα1α1∧· · ·∧ dα14

    α14

    )×(1+α2α4α13(α8+α7α12)