Producing Exotic hadrons at the EIC
Transcript of Producing Exotic hadrons at the EIC
Producing Exotic hadrons at the EIC
Alessandro PilloniSnowmass, RF7 working group, September 16th, 2020
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0 40 80 120Center of Mass Energy [GeV]
Spin and Flavor Structure of the Nucleon and Nuclei
QCD at Extreme Parton Densities-
Saturation
Tomography (p/A)
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Peak
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EICOptimization for high Ecm
Internal Landscape of the Nucleus
EICOptimization for low Ecm
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EIC Luminosity vs. Energy
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F. Willeke, May 2020
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Spectroscopy working group
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β’ Exclusive production of XYZβ’ Polarization observables in XYZβ’ Semi-inclusive production of XYZβ’ Potential access to heavy hybridsβ’ Production of XYZ in cold nuclear
matter, multiplicity studies
Contributing to the EIC Yellow Report,http://www.eicug.org/web/content/yellow-report-initiative
J. Stevens, convener
Exclusive (quasi-real) photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC 7
< ππ¬ππβ² |π|ππΎππ >= β
π,β°
πππππ
π―ππ=ππΎ,ππ¬
πΌ1β―πΌπ π«πΌ1β―πΌπ;π½1β―π½πβ¬
ππππβ²
π½1β―π½π
β’ XYZ have so far not been seen in photoproduction: independent confirmationβ’ Not affected by 3-body dynamics: determination of resonant natureβ’ Experiments with high luminosity in the appropriate energy range are promisingβ’ We study near-threshold (LE) and high energies (HE)β’ Couplings extracted from data as much as possible, not relying on the nature of XYZ
M. Albaladejo et al. [JPAC], 2008.01001
Exclusive (quasi-real) photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC 7
< ππ¬ππβ² |π|ππΎππ >= β
π,β°
πππππ
π―ππ=ππΎ,ππ¬
πΌ1β―πΌπ π«πΌ1β―πΌπ;π½1β―π½πβ¬
ππππβ²
π½1β―π½π
VMD is used to couple the incoming photonto a vector quarkonium V
β’ XYZ have so far not been seen in photoproduction: independent confirmationβ’ Not affected by 3-body dynamics: determination of resonant natureβ’ Experiments with high luminosity in the appropriate energy range are promisingβ’ We study near-threshold (LE) and high energies (HE)β’ Couplings extracted from data as much as possible, not relying on the nature of XYZ
Exclusive (quasi-real) photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC 7
< ππ¬ππβ² |π|ππΎππ >= β
π,β°
πππππ
π―ππ=ππΎ,ππ¬
πΌ1β―πΌπ π«πΌ1β―πΌπ;π½1β―π½πβ¬
ππππβ²
π½1β―π½π
Top vertex from measured π¬ β πβ° decay width
β’ XYZ have so far not been seen in photoproduction: independent confirmationβ’ Not affected by 3-body dynamics: determination of resonant natureβ’ Experiments with high luminosity in the appropriate energy range are promisingβ’ We study near-threshold (LE) and high energies (HE)β’ Couplings extracted from data as much as possible, not relying on the nature of XYZ
Exclusive (quasi-real) photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC 7
< ππ¬ππβ² |π|ππΎππ >= β
π,β°
πππππ
π―ππ=ππΎ,ππ¬
πΌ1β―πΌπ π«πΌ1β―πΌπ;π½1β―π½πβ¬
ππππβ²
π½1β―π½π
Bottom vertex from standard photoproduction pheno,exponential form factors to further suppress large t
β’ XYZ have so far not been seen in photoproduction: independent confirmationβ’ Not affected by 3-body dynamics: determination of resonant natureβ’ Experiments with high luminosity in the appropriate energy range are promisingβ’ We study near-threshold (LE) and high energies (HE)β’ Couplings extracted from data as much as possible, not relying on the nature of XYZ
From threshold to high energy
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β’ Fixed-spin exchanges expected to hold from threshold to moderate energies (LE):Contain full π dependence
β’ π‘ channel grows as π π, exceeding unitarity bound:Reggeized tower of particles with arbitrary spin at HE
4π(π‘)π(π‘)
π 0
πβπ
π©ππβ²π
πππβ²π
(ππ‘)
πππ(π‘)
(π , π‘)
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π‘ β πβ°2 βΆ βπΌβ²Ξ(π β πΌ(π‘))[
1 + ππβπππΌ(π‘)
2]
π
π 0
πΌ(π‘)βπ
Holds at LE, fixed spin Holds at HE, resummationof leading π power
π photoproduction
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β’ The ππ are charged charmoniumlike 1+β states close to open flavor thresholdsβ’ Focus on ππ 3900 + β π½/π π+, ππ 10610 +, ππ
β² 10650 + β Ξ₯(ππ) π+
β’ The pion is exchanged in the π‘-channelβ’ Sizeable cross sections especially at LE
π photoproduction
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β’ Focus on the famous 1++ π 3872 β π½/π π, πβ’ Studying also π 6900 β π½/π π½/π (assumed 0++)β’ π and π exchanges give main contributions:
need to assume the existence of a OZI-suppressed π 6900 β π½/π πβ’ Extremely suppressed cross sections at HE: LE most promising
π (vector) photoproduction
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π πβ² =π2(πβ² β πΎππ)
π2(π β πΎππ)βΌ 0.55 π2(π β πΎππ) =
6ππβ¬(π β πΎππ)Ξπ
PS(π β πΎππ)
How to rescale from π½/π to πβ² ?
β’ Focus on the 1ββ π 4260 β π½/π π+πβ , check with πβ² β π½/π π+πβ
β’ Diffractive production, dominated by Pomeron (2-gluon) exchangeβ’ Good candidates for EIC: diffractive production increases with energy!β’ We have πΎπ-pomeron coupling from our analyses 1606.08912, 1907.09393
π (vector) photoproduction
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β’ Focus on the 1ββ π 4260 β π½/π π+πβ , check with πβ² β π½/π π+πβ
β’ Diffractive production, dominated by Pomeron (2-gluon) exchangeβ’ Good candidates for EIC: diffractive production increases with energy!β’ We have πΎπ-pomeron coupling from our analyses 1606.08912, 1907.09393
How to rescale from π½/π to π(4260) ?
π π =πππ
ππ
π2(π β πππ)
π2(π β πΎππ)
π2(πβ² β πππ)
π2(πβ² β πππ)
We assume VMD and π2 π β πππ = π2 π β πππ Γ π2(ππ β ππ) (Novikov & Shifman)
Caveat : π΅π (π β πππ) only known times the leptonic width Ξπππ
π (vector) photoproduction
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Existing data allow to put a 95% upper limiton the ratio of πβ²/π(4260) yields
Assuming previous formula, one gets:Ξπππ = 930 ππ
(cfr. hep-ex/0603024, 2002.05641)
π΅π π β π½/πππ = 0.96%π π = 0.84
Data from H1hep-ex/971112
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Primakoff X photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC
Using measurement of Ξ(X β πΎπΎβ) from Belle, one can get predictions for Primakoff
Makes use of the ion beam, enhancement of cross sections as π2
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Diffractive semi-inclusive ππ ph.
A. Pilloni β Producing Exotic Hadrons at the EIC
If the target fragments are separated from the beam ones, one can invoke Regge factorization
= Im
Quark-Regge duality allows to replace the intermediate hadrons with Pomeron , prediction reliable for π₯π΅ βΌ 1, π‘ βͺ ππΎπ
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ππ π
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Semi-inclusive π production
A. Pilloni β Producing Exotic Hadrons at the EIC
For large π2 one can invoke NRQCD factorizationto describe quarkonium(-like) production
Perturbative partonic matrix element, calculable
Nonperturbative transition matrix element π π β π»
fitted from data
X. Yao
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Semi-inclusive π production
A. Pilloni β Producing Exotic Hadrons at the EIC
One can assume the same NRQCD factorization for exotics, independent of their internal structure
Artoisenet and Braaten, PRD81, 114018 from Tevatron data
If one consider the first term only, it leads to
X. Yao
Joint Physics Analysis Center
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Exclusive reactions:2008.01001
Inclusive reactions:in progress
Code available onhttps://github.com/dwinney/jpacPhoto
Contact : [email protected]
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Another π?
A. Guskov
A. Pilloni β Producing Exotic Hadrons at the EIC
COMPASS claimed the existence of a statedegenerate with the π(3872), but with πΆ = 1
Large photoproduction cross sectionA. Guskov
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Exclusive ππ photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC
At Jlab12 measurements of direct ππproduction are being performed
Using VMD, BR ππ β π½/π π βΌ 1%
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Polarized ππ photoproduction
A. Pilloni β Producing Exotic Hadrons at the EIC
βΌ π πΌ(π’)
β’ s channel resonances significant at low energies: u channel dominates at high energies
β’ Main background from N(*) trajectories
β’ Estimated ππ coupling upper bound of same order of magnitude as π(β) couplingβ’ Reggeization suppresses ππ due to larger mass (smaller trajectory intercept)β’ We estimate that the ππ trajectories will hardly be visible at the EICβ’ ππ searches still possible: π channel at higher energies!
Cao et al., Phys.Rev. D 101, 074010 (2020)E. Paryev, arXiv:2007.01172 [nucl-th] (2020)
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Diffractive semi-inclusive ππ ph.
A. Pilloni β Producing Exotic Hadrons at the EIC
Very large cross sections obtained, checking the validity of approximations in this range
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Production of other exotics
A. Pilloni β Producing Exotic Hadrons at the EIC
Other cross sections have been estimated, generally quite largeGuo et al. EPJC74, 9, 3063
Guo et al. CTP, 61, 354
Estimates can be given using MC generators, using coalescence model and assuming a molecular nature for
the exotics
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Comparison: EIC vs. others
Flexibility in the production mechanism Flexibility in energy (no Ξπ) Less clean environment
Too late (?) for charm physics
Larger luminosity (4.5 Γ 1032 cmβ2sβ1 at LHCb)Lower cross sections Better efficiencies for neutrals (?)
Polarized electron & ion beams
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Multiscale system
A. Pilloni β Producing Exotic Hadrons at the EIC
ππ β« πππ£ β« πππ£2ππ βΌ 5 GeV,ππ βΌ 1.5 GeV
π£π2 βΌ 0.1, π£π
2 βΌ 0.3
Systematically integrateout the heavy scale,
ππ β« ΞππΆπ· Full QCD NRQCD pNRQCD
Factorization (to be proved)of universal LDMEs
Good description of many production channels,some known puzzles (polarizations)
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Esposito, AP, Polosa, Phys.Rept.
HadSpec, PRD
The spectrum of hadron excitations is incredibly rich
Several new observations beyond the minimal quark content
QCD spectrum
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π π
π π = βπΆπΉπΌπ
π+ ππ
(Cornell potential)
Effective theories(HQET, NRQCD, pNRQCD...)
Integrate out heavy DOFβ
Quarkonium orthodoxy & exotic
approximate heavy quark spin symmetry (HQSS)
A. Pilloni - Producing Exotic Hadrons at the EIC
spectrum, decay & production rates
A host of unexpected resonances have appeared
Hardly reconciled with usual charmonium interpretation
Esposito, AP, Polosa, Phys.Rept. 668
Bottomonium exotic sector notequally well explored
β’ Discovered in π΅ β πΎ π β πΎ π½/π ππ
β’ Quantum numbers 1++
β’ Very close to π·π·β threshold
β’ Too narrow for an above-treshold charmonium
β’ Isospin violation too big Ξ πβπ½/π π
Ξ πβπ½/π π~0.8 Β± 0.3
β’ Mass prediction not compatible with ππ1(2π)
π = 3871.68 Β± 0.17 MeVππ β ππ·π·β = β3 Β± 192 keVΞ < 1.2 MeV @90%
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π(3872)
A. Pilloni β Producing Exotic Hadrons at the EIC
Sizeable prompt production at hadron colliders, βΌ 5% of π(2π)
πππ Γ π΅(π β π½/πππ) = (1.06
π+πβ β ππ 3900 +πβ β π½/π π+πβ and β π·π·β +πβ
π = 3888.7 Β± 3.4 MeV, Ξ = 35 Β± 7 MeV
π+πβ β ππβ² 4020 +πβ β βπ π+πβ and β π·β0π·β+πβ
π = 4023.9 Β± 2.4 MeV, Ξ = 10 Β± 6 MeV
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Charged π states: ππ 3900 , ππβ²(4020)
Two states π½ππΆ = 1+β appear
slightly above π·(β)π·β thresholds
Charged quarkonium-like resonances have been found, 4q needed
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Pentaquarks!LHCb, PRL 115, 072001LHCb, PRL 117, 082003
Quantum numbers
π½π =3
2
β
,5
2
+
or3
2
+
,5
2
β
or5
2
+
,3
2
β
Two states seen in Ξπ β π½/π π πΎβ,evidence in Ξπ β π½/π π πβ
π1 = 4380 Β± 8 Β± 29 MeVΞ1 = 205 Β± 18 Β± 86 MeV
π2 = 4449.8 Β± 1.7 Β± 2.5 MeVΞ2 = 39 Β± 5 Β± 19 MeV
A. Pilloni β Producing Exotic Hadrons at the EIC
LHCb, PRL 122, 222001 Higher statistics analysis revealed a two-
peak structure of the narrow state,plus a new lighter one
Quantum numbers still unknown
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Models
MoleculeBound or virtual state generated by long-range exchange forces
MultiquarkSeveral (cluster)
of valence quarks
HybridsContaining gluonicdegrees of freedom
π±/ππ π
π HadroquarkoniumHeavy core interacting with a light cloud via Van der Waals forces
Rescattering effectsStructures generated by
cross-channel rescattering, very process-dependent
Compact
Extended
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Hybrid production
Suprisingly, no calculationfor heavy hybrid productionhas been carried out so far
The only example for B decaysis Petrov et al. PRD58, 034013
Room for improvement and inclusion of the large number of gluons at small x
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Doubly heavy
Lots of attention recently on tetraquark and baryons with two heavy quarks, driven by LHCb and lattice results
Quigg and Eicthen, PRL119, 202002 Esposito, AP et al. PRD88, 054029
Karliner and Rosner, PRD90, 094007 Karliner and Rosner, PRL119, 202001
Francis et al. PRL118, 142001
MC code available, GENXICC2.0, which implements the heavy diquark in PythiaNRQCD approach in π+πβ collisions in Chen et al. JHEP1412, 018