Jet Studies for Les Houches - jthaler.net · 2017-06-21 · Jet Physics = Innovative Approaches to...

Jesse Thaler — Jet Studies for Les Houches 1

Jesse Thaler

Les Houches Workshop — June 6, 2017

Jet Studies for

Les Houches


Question to Les Houches royalty: !

First dedicated jet session at LH 2007 (Salam/Wobisch)?First official “jet convener” at LH 2011 (Soyez)?

[JADE,1979][Hanson, et al., 1975]

Over Four Decades of Jets and QCD!


100 MeV++

1.3 GeV++

4.2 GeV++

0++

u,d,s

c

b

g

•

•Jets from theStandard Model

micro-jet≈ 65%

++ = plus gluonic radiation


100 MeV++

1.3 GeV++

4.2 GeV++

0++

173 GeV++

80/91 GeV

u,d,s

c

b

g

•

•

t•

W/Z

H ••

125 GeV

Jets from theStandard Model

micro-jet≈ 70%

≈ 70%

≈ 60%

≈ 65%

++ = plus gluonic radiation


100 MeV++

1.3 GeV++

4.2 GeV++

0++

173 GeV++

80/91 GeV

u,d,s

c

b

g

•

•

t•

W/Z

H ••

125 GeV

≈ 70%

≈ 70%

≈ 60%Jet Grooming

⇒

Jet Discrimination

vs.

Substructure Toolbox:


0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4

Events

1−10

1

10

210

310

410

510

610

710QCD W+jets

+jetstt Z+jets

Z'(50) Z'(100)

Z'(150) Z'(200)

Data

(13 TeV)-1

35.9 fbCMS Preliminary

1,DDT

2 AK8 N

0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4

Data

/Sim

ula

tion

0

1

2

Nu

mb

er

of

eve

nts

/5 G

eV

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400Data

Multijet pred.

Total SM pred.

qq+jets→W

qq+jets→Z

=135 GeVZ'

=1/6, mq

Z'(qq), g

(13 TeV)-1

35.9 fbCMS Preliminary

: 700-800 GeVT

p

(GeV)PUPPI

SDAK8 m

60 80 100 120 140 160 180 200 220 240

Data

/Pre

dic

tion

0.9

1

1.1

E.g. CMS Boosted Z’ Search

Recoil Jet(s)

with N2 + Decorrelation + Soft Drop + PUPPI

pp

Z or Z’ ?

[CMS PAS EXO-17-001;using Moult, Necib, JDT, 1609.07483; Dolen, Harris, Marzani, Rappoccio, Tran, 1603.00027;Larkoski, Marzani, Soyez, JDT, 1402.2657; Bertolini, Harris, Low, Tran, 1407.6013]

Z’-like q/g-like


Back to the Future

Z' mass (GeV)50 60 100 200 300 400 1000

qcouplin

g, g

0.02

0.03

0.04

0.1

0.2

0.3

0.4

1CMSPreliminary (13 TeV)

-135.9 fb

UA2

CDF Run 1

CDF Run 2

Observed

Expected

1 std. deviation±

2 std. deviation±

γ, ISR -1ATLAS13, 15.5 fb

, ISR jet-1ATLAS13, 15.5 fb

, Scouting-1CMS8, 18.8 fb

Z Width (indirect)

[CMS PAS EXO-17-001]

Jet Physics = Innovative Approaches to Hadronic Final States

1993

2017

Yes, searching for abump on a bump!


Back to Les Houches 2015


Jesse Thaler — Report of the Les Houches Quark/Gluon Subgroup

Jesse Thaler

Les Houches Workshop — June 10, 2015

Report of the Les Houches Quark/Gluon Subgroup

1

on behalf of Andy Buckley, Jon Butterworth, Mario Campanelli, Marat Freytsis, Peter Loch, Philippe Gras, Deepak Kar, Simon Plätzer, Andrzej Siodmok,

Peter Skands, Dave Soper, Gregory Soyez, Frank Tackmann

= Jets are Les H.


Jesse Thaler — Report of the Les Houches Quark/Gluon Subgroup 2

[Larkoski, JDT, Waalewijn,1408.3122] [based on Berger, Kucs, Sterman, hep-ph/0303051; Ellis, Vermilion, Walsh, Hornig, Lee, 1001.0014]

[see also Larkoski, Salam, JDT, 1305.0007; Larkoski, Neill, JDT, 1401.2158] [For a more complete catalog, see Gallicchio, Schwartz, 1106.3076, 1211.7038]

0 1 2

λκβ

κ

β0

1

2 pD

T

eβ

width mass

multiplicity

λκβ =

∑

i∈jet

zκiθβi

momentum fraction

angle to recoil-free axis

Hunting the White Whale: Quarks vs. Gluons

Probe radiation pattern with e.g. Generalized Angularities

Quark: CF = 4/3 Gluon: CA = 3vs.

Cartoon:

zi

θi

LHA (Les Houches Angularity)


Coming soon to JHEP!


Idealized Quark/Gluon Distributions

Large variations for gluon jets (not tuned to LEP)

0

1

2

3

4

5

6

0 0.2 0.4 0.6 0.8 1

Q=200 GeV

R=0.6

pg(1 0.5)

1 [LHA]

Gluon, hadron-level

Pythia 8.215Herwig 2.7.1Sherpa 2.2.1Vincia 2.001

Deductor 1.0.2Ariadne 5.0.

Dire 1.0.0Analytic NLL

0

1

2

3

4

5

6

0 0.2 0.4 0.6 0.8 1

Q=200 GeV

R=0.6

pq(1 0.5)

1 [LHA]




e+e– → quarks (CF = 4/3) e+e– → gluons (CA = 3)

LHA =

X

i

zi

p

θi

vs.

[Gras, Hoeche, Kar, Larkoski, Lönnblad, Plätzer, Siódmok, Skands, Soyez, JDT, 1704.03878;based on Soyez, JDT, Freytsis, Gras, Kar, Lönnblad, Plätzer, Siodmok, Skands, Soper, 1605.04692]

LHA =

X

i

zi

p

θi

Q = 200 GeVR = 0.6

Q = 200 GeVR = 0.6


Impact on Quark/Gluon Separation

0

0.5

1

1.5

2

0 0.2 0.4 0.6 0.8 1

Q=200 GeV

R=0.6d/d1 0.5

1 [LHA]

Separation, hadron-level




Differential Integrated Values

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Hadron-level




Affects both IRC unsafe and IRC safe observables

LHA =

X

i

zi

p

θi

Q = 200 GeVR = 0.6

λ1

2

(

Q(λ)−G(λ))2

Q(λ) +G(λ)


Testing Shower Variants

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Ariadne 5.0. , hadron-level

baselineno g qqno swing

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Dire 1.0.0, hadron-level

baselineno g qqMC@NLO1-loop s

3-loop s

string had.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Herwig 2.7.1, hadron-level

baselineno g qqno CR

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Pythia 8.215, hadron-level

baselineno g qqno ME

2-loop s

CR1

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Sherpa 2.2.1, hadron-level

baselineno g qqNjet=1Njet=0

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Vincia 2.001, hadron-level

baselineno g qqno ME

1-loop s

alt QE

Large impact from color reconnection

Σ(eβ) =e−γER0(eβ)

Γ (1 +R0(eβ))e−R(eβ) e

−fNGL(eβ)


NLL Resummation plus NP Correction

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

(0,0) (2,0) (1,0.5) (1,1) (1,2)

Q=200 GeV

R=0.6

LL

Separation:

Angularity: ( , )

Analytic NLL, hadron-level

baselineno g qqno NGLs1-loop s

no Ci in 0

no Ci in 0

alt F( ) F () =

220exp

−

4

2

20

]

) = 0.

Z

0

Z

0

=1

β − 1

Ω0

REJ

1−

Ξ0

REJ

β−1!

Ωg0

Ωq0

=Ξg0

Ξq0

=CA

CF.

NLL with Non-Global Logs

Shift from NP Shape Function

Convolution (Simplified)

Default: Full Casimir Scaling↑: No Casimir Scaling for Ξ0 ↓: No Casimir Scaling for Ω0 or Ξ0

dσ

deβ=

Z

deβ d σ(eβ)F () δ (eβ − eβ − )

Large impact from nonperturbative assumptions


Differences Persist at LHC

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 0.2 0.4 0.6 0.8 1 1.2

pTmin=100 GeV

Separation:

R

0.5 [LHA], Hadron-level, plain jet


LHC sensitive to jet radiationpatterns (esp. gluons)

0

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1

pTmin=100 GeV

R=0.4p2j(1 0.5)

10.5 [LHA]

2j, Hadron-level, plain jet


0

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1

pTmin=100 GeV

R=0.4pZj(1 0.5)

10.5 [LHA]

Z+j, Hadron-level, plain jet


pp → Z + jet85% quarks @ 100 GeV

pp → dijet75% gluons @ 100 GeV

Varying Jet Radius


Recommendations

[Gras, Hoeche, Kar, Larkoski, Lönnblad, Plätzer, Siódmok, Skands, Soyez, JDT, 1704.03878;based on Soyez, JDT, Freytsis, Gras, Kar, Lönnblad, Plätzer, Siodmok, Skands, Soper, 1605.04692]

Scrutinize aspects of final-state parton shower!

Gluon splitting to quark/antiquarkColor reconnection models

Default choice of αs

!

New tuning/measurement campaigns !

LEP: Tune to existing e+e– → b b g measurementsLEP: Measure Les Houches Angularity (LHA, β = 1/2)

LHC: Differential studies in multiple channels at multiple pT and R!

Further analytic studies !

Pursue (N)NLL + (N)NLO calculationsFirst-principles understanding of NP corrections?

_


Assess matching/merging uncertainties and impact on jet substructure methods (and vice versa)

Action Items for LH 2017Overlap with other working groups

Develop concrete plan for LHC (and LEP) jet shapemeasurements and parton shower tuning (see backup)

Identify new uses for quark/gluon tagging,(e.g. improved PDF extraction?)

Beyond quark/gluon discrimination, correct modeling ofjet radiation will benefit many LHC studies


Further Goals for Les Houches 2017


Precision Jet Substructure Calculations!

Improved control with jet grooming (e.g. top mass, αs extraction)Quantifying impact of soft QCD effects (underlying event and hadronization)

Charmonium polarization puzzle in identified jetsHeavy ion physics: jet shapes in medium, probe QGP with boosted objects

…!

Advanced Tagging Strategies!

Interplay of jet radius, jet discriminants, and jet grooming (e.g. dichroic)Exploiting charm/bottom tags (e.g. gluon splitting to heavy flavor)

More refined tagging categories (e.g. longitudinal vs. transverse W/Z bosons)Machine learning: multi-category classification, physics-inspired network design

…!

Many points of contact with other working groups

Two Broad ThemesFrom the wiki and pre-LH discussions


Deep Thinking meets Deep Learning

Starting from well-defined physics goal…

Blackboards, Coffee,Mountains, Inspiration

Validation inSimulation/Data/Calculations

⇒

Construct ExplicitOptimization Problem

Training inSimulation/Data

⇒⇔


Deep Thinking meets Deep Learning

0.0 0.1 0.2 0.3 0.40

2

4

6

8

10

12

N2(2)

ProbabilityDensity

N2(2)

Pythia 8.219

R=1.0, pT>500 GeV, m [80, 100] GeV

ZLight QuarkGluon

[e.g. Moult, Necib, JDT, 1609.07483; Datta, Larkoski, 1704.08249; de Oliveira, Kagan, Mackey, Nachman, Schwartzman, 1511.05190]

Energy Correlatorsfrom Power Counting

ConvolutionalNeural Network

M-Body Discrimination

13 TeV, pT > 500 GeV, R = 0.8

Pythia8

+ -

+ - + -

+ - + -

Dense Network ofN-subjettiness Values

Continuum of approaches, ripe for cross fertilization

Optimize for performance and robustness (and calculability)

vs.q/g W/Ze.g.


My goal for Les Houches:Hunting the next white whale for jet physics


Extracting Strong Coupling Constant

Determine αs from

LHC jet substructure?

Clarify role of jet groomingfor precision studies?!Highlight ways to controlsoft QCD corrections?!Inform strategies usedat lepton colliders?!Ignite progress in(N)NLO substructure? Needed to get in the PDG!


Proof of ConceptSoft-dropped jet mass

⇒ mg

Grooming simplifies structure of calculation, reduces NP effects!

[Frye, Larkoski, Schwartz, Yan, 1603.06375, 1603.09338; see also Marzani, Schunk, Soyez, 1704.02210]

First NNLL + O(αs2) result for substructure in pp (!)

/

- -

( )

= =

+ > =

++ ( + )

++ ( + )


0

0.05

0.1

0.15

0.2

0.25

10-6

10-5

10-4

10-3

10-2

10-1

100

C1(2)

R=1, pt>3 TeVzcut=0.1

plain jetβ=2β=1β=0β=-0.5

Pythia 8

mg2/pT

2

β < 0 β = 0 β > 0

Less Grooming

β → ∞β → –∞

More Grooming

![Larkoski, Marzani, Soyez, JDT, 1402.2657; see also Butterworth, Davison, Rubin, Salam, 0802.2470; Dasgupta, Fregoso, Marzani, Salam, 1307.0007]

0

0.05

0.1

0.15

0.2

0.25

10-6

10-5

10-4

10-3

10-2

10-1

100

C1(2)

R=1, pt>3 TeVzcut=0.1

solid: mult. em.plain jetβ=2β=1β=0β=-0.5

NLL Resummation

mg2/pT

2

Sudakov factor

Kink from zcut

⇒ mg

Systematic Strategy for αs?Scanning soft-drop variants?


for jet vetos

N-subjettiness forboosted objects

N-jettiness forNNLO calculations

[Stewart, Tackmann, Waalewijn, 1004.2489; Kim, 1011.1493; JDT, Van Tilburg, 1011.2268,1108.2701; Boughezal, Focke, Liu, Petriello, 1504.02131;Gaunt, Stahlhofen, Tackmann, Walsh, 1505.04794; Stewart, Tackmann, JDT, Vermilion, Wilkason, 1508.01516; JDT, Wilkason, 1508.01518]

Jet 2

Jet b Jet a

Soft

Jet 3

Jet 1b

a

1

32

p p

ℓ−

ℓ+

0 0.2 0.4 0.6 0.8 10

0.01

0.02

0.03

0.04

0.05

0.06

3/

2 of jet

Rela

tive o

ccure

nce

145 GeV < mj < 205 GeV

Top jets

QCD jets

N-jettiness

XCone for exclusive cone jets

Benefits of Cross-pollinationwide-angle ⇔ boosted regimes


Jet Studies for Les Houches

Pursuing white whale of quark/gluon discrimination

reveals (non)perturbative uncertainties in jet radiation

2015:

Pursuing _______________________________

!

reveals __________________________________

2017:

Looking forward to a fun, productive workshop!

(topic of interest to jet physics community)

(insights with broader implications for QCD and beyond)


Backup Slides


Innovative Approaches to Hadronic Final States

SearchesMeasurements

(GeV)T

Leading top p0 200 400 600 800 1000 1200

(pb/G

eV

)(1

)

T/d

pσ

d

4−10

3−10

2−10

1−10

1

10

210

Parton level

Data (resolved)

Data (boosted)

Powheg

aMC@NLO

Madgraph

(13 TeV)-12.53 fb

CMS

Preliminary

[e.g. CMS-PAS-JME-15-002; CMS-PAS-TOP-16-013; ATLAS-CONF-2016-014][e.g. Lapsien, Kogler, Haller, 1606.04961; Larkoski, Moult, 1510.08459; Schwaller, Stolarski, Weiler, 1502.05409]

Z' mass [TeV]0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

) [p

b]

t t

→ B

R(Z

' ×

Z'

σ

2−10

1−10

1

10

210

310

Observed 95% CL limit

Expected 95% CL limit

uncertaintyσExp. 1

uncertaintyσExp. 2

1.3)×/m=1.2%) (LO Γ(TC2

Z'

1.3)×/m=3%) (LO Γ(TC2

Z'

ATLAS Preliminary

-1 = 13 TeV, 3.2 fbs

Sε

0 0.2 0.4 0.6 0.8 1

Bε

4−10

3−10

2−10

1−10

CMSSimulation Preliminary 13 TeV

| < 1.5η < 1000 GeV, |T

800 < p

R(top,parton) < 0.6∆

η and T

flat p

CMSTT min. m

CMSTT top m

Filtered (r=0.2, n=3) m

RecHTT V2 f

HTT V2 m

=0.5) mcut

Pruned (z=0.1, r

Q-jet volatility

=0) mβSoftdrop (z=0.1,

=1) mβSoftdrop (z=0.2,

Trimmed (r=0.2, f=0.03) m

2τ/

3τUngroomed

) (R=0.2)χlog(

φ

3− 2− 1− 0 1 2 3

η

3−

2−

1−

0

1

2

3

HOTVREvent 2clustered with HOTVR

Performance

-

-

-

( )

( )

( )=

/

( )

( )

( )

+ -

[ ]

Strategies Calculations Scenarios


Jesse Thaler — Report of the Les Houches Quark/Gluon Subgroup 3

What is a Quark Jet? From lunch/dinner discussions

A quark parton

A Born-level quark parton

The initiating quark parton in a final state shower

An eikonal line with baryon number 1/3and carrying triplet color charge

A quark operator appearing in a hard matrix elementin the context of a factorization theorem

A parton-level jet object that has been quark-tagged using a soft-safe flavored jet algorithm (automatically collinear safe if you sum constituent flavors)

A phase space region (as defined by an unambiguous hadronic fiducial cross section measurement) that yields an enriched sample of quarks (as interpreted by some suitable, though fundamentally ambiguous, criterion)

Ill-Defined

Well-Defined What we mean

What people

sometimes

think we mean

Quark

as adjective

Quark

as noun


Systematic Differences between Generators

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

50 100 200 500 1000

R=0.6

s= s0

LL

Separation:

Q [GeV]

0.5 [LHA], hadron-level




0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 0.2 0.4 0.6 0.8 1 1.2

Q=200 GeV

s= s0

LL

Separation:

R

0.5 [LHA], hadron-level




Differences in both absolute and relative trends

Varying Collision Energy Varying Jet Radius


Proposed Systematic LHC Study

Strategy:

Observables:!

Samples:!

!

!

Variations:

multiplicity, pTD

, LHA, width, thrust, …

!

V + jet = quark-enrichedvs. dijet = gluon-enriched(No need to diagonalize?)!

Multiple jet pT rangesMultiple jet radii e.g. R = 0.2, 0.4, 0.6, 0.8,1.0With & without grooming e.g. mMDT (soft drop β=0, zcut=0.1)

+

+

+

+

( )

(Over)constrain final-state parton shower

Key task for jet physics community

In principle, benefits every LHC measurement

Jet Studies for Les Houches - jthaler.net · 2017-06-21 · Jet Physics = Innovative Approaches to...

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Transcript of Jet Studies for Les Houches - jthaler.net · 2017-06-21 · Jet Physics = Innovative Approaches to...