dis 2010 xviii international workshop on deep-inelastic … · 2018. 11. 18. · dis 2010 xviii...

DIS 2010XVIII International Workshop onDeep-Inelastic Scattering and Related SubjectsApril 19 - 23, 2010, Florence, Italy

Experimental summary of QCD session

Claudia Glasman (UAM) & Stefan Tapprogge (Mainz)

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Experimental summary of QCD session 1

QCD session

• 27 experimental talks in QCD session:

QCD @ work......from e+e− to µ scattering to ep to heavy ions

• − Belle/BaBar: Heavy quarkonium and quarkonium-like states; Alexander Ku zmin

• − Belle/BaBar: Hadron production from e+e− ISR, two-photons, Υ states; Fabio Anulli

• − COMPASS: Production of heavy hyperons in DIS; Natalia Rossiyskaya

• − HERMES: Nuclear attenuation - 2 D dependencies; Klaus Rith for Inti L ehmann

• − HERMES: A-dependence of transverse Lambda polarisation; Klaus Rit h

• − HERMES: Azimuthal modulations in the spin-averaged SIDIS cross sec tion for charged pions;

• − HERMES: Francesca Giordano

• − PHENIX: Studies of jet fragmentation in medium and vacuum using two- particle correlations

• − PHENIX: and direct jet reconstruction; Matthew Nguyen

Claudia Glasman (UAM) & Stefan Tapprogge (Mainz) DIS 2010 (Fl orence): April 23, 2010


QCD session


Challenging pQCD to the extreme...• − CDF: Limitations on the predictions for pT-balance in events wit h a Z-boson and jets;

• − CDF: Alexander Paramonov

• − CDF: Minimum bias and underlying event studies; Niccolo’ Moggi

• − CDF: W+charm; Shulamit Moed

• − DØ: Photon+3 jets and and direct photon pair production; Lee Saw yer

• − D0: Determination of the strong coupling constant from the incl usive jet cross section in pp̄

• − D0: collisions at√

s = 1.96 TeV; Lars Sonnenschein

• − D0: Dijet angular distributions, dijet mass cross section and d ijet azimuthal decorrelation;

• − D0: Zdenek Hubacek

• − D0: Multi-jet cross section, inclusive three-jet cross sectio n, angular correlations in minimum

• − D0: bias; Lee Sawyer



QCD session


Challenging pQCD to the extreme...• − H1: Observation of the hadronic final state charge asymmetry in h igh Q2 DIS; Gunter

• − H1: Grindhammer for Daniel Traynor

• − H1: Transverse momentum of charged particles at low Q2; Anastasia Grebenyuk

• − H1: Strangeness production at high Q2; Karim Daum for Julia Ruiz Tabasco

• − H1: Jet Production at low and high Q2 and determination of the strong coupling; Roman Kogler

• − ZEUS: Jet cross sections in photoproduction; Denys Lontkovskyi

• − ZEUS: Jet cross sections in DIS; Claudia Glasman

• − ZEUS: Three-subjet distributions in NC DIS; Juan Terron

• − ZEUS: Scaled momentum spectra in DIS; Krystyna Olkiewicz

• − ZEUS+H1: Prompt photon production; Tobias Hass for David Saxon




QCD @ the energy frontier......the future is already here!!!

• − ALICE: Results on charged particle production; Silvia Masciocchi

• − LHCb: prompt V0 and inclusive charged particle production, jet st udy; Manuel Schiller

• − CMS: QCD physics; Krisztian Krajczar

• − ATLAS: QCD and final states; Heather Gray


QCD @ work......from e+e− to µ scattering to ep to heavy ions


BaBar (Fabio Anulli)

Two-photon interactions in single-tag mode: γγ∗ → ηc; transition form factors



Belle (Fabio Anulli)



COMPASS (Natalia Rossiyskaya)

Are the yields of hyperons and antihyperons different?



HERMES (Inti Lehmann; presented by Klaus Rith)



HERMES (Klaus Rith)



PHENIX (Mathew Nguyen)


Challenging pQCD to the extreme...


CDF (Niccolo’ Moggi)

• Drell-Yan: pp̄ → γ∗/Z0 → e+e− or µ+µ−

• → everything except ll̄ in final state is underlying event

• → Drell-Yan events very clean probe of underlying event• → Study of UE observables in DY• → and comparison to leading-jet UE

• → “Transverse” region most sensitive to UE in DY and jets

p

p

γ∗/ Zq

q

l

l

→ UE observables constant with lepton-pair PT in “Transverse”→ Adequate agreement between DY and leading-jet UE results fo r→ pT > 50 GeV



H1 (Anastasia Grebenyuk)

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H1 (Julia Ruiz Tabasco; presented by Karim Daum)

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H1 + ZEUS: fragmentation functions

(ZEUS: Krystyna Olkiewicz; H1: Daniel Traynor, presented b y Gunter Grindhammer)

xp = 2pQ

Q (GeV)10 210

p x

∆/±1/

N n

−210

−110

1

10

210

310

410

510−1ZEUS 38 pb

−1ZEUS 440 pb−1H1 44 pb

−1ZEUS 38 pb−1ZEUS 440 pb

−e+e

rangepx

0.0 − 0.02 (x30)

0.02 − 0.05 (x5)

0.05 − 0.1 (x2)

0.1 − 0.2

0.2 − 0.3

0.3 − 0.4

0.4 − 0.5

0.5 − 0.7

0.7 − 1.0

ZEUS

→ Very precise data → input to fits

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H1 + ZEUS (David Saxon; presented by Tobias Haas)

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DØ (Lee Sawyer)

• Di-photon direct production → shedding light on QCD• → test of pQCD• → major background to H → γγ• → first double-differential cross sections• → → comparison with predictions (DIPHOX, RESBOS and PYTHIA)

→ None of the theoretical predictions describes the data in th e whole→ measured range simultaneously



CDF (Shulamit Moed)

• W + c−jet production: dominated by s − g fusion → sensitive to Vcs

cg

s W

W

c

s

g

→ sensitive to g and s pPDFs at µR = MW :

→ → measurements at→ → TevaTron test→ → universality of sPDF→ → and its evolution→ background to top,→ Higgs, stop production

→ and to new physics in hadron colliders

σWc × Br(W → lν) = 21.1 ± 7.1(stat) ± 4.6(syst) pb

→ NLO prediction: 11.2 ± 2.2 pb

→ Measurements provide direct experimental→ evidence of sg → Wc process



DØ (Zdenek Hubacek)

• Jet production dominant at hadron colliders → highest reach in energy and• probe of hard interactions at shortest distances• → dijet production ideal to test SM and search for new• → physics• → angular correlations directly sensitive to underlying• → dynamics

χdijets = exp(|y1 − y2|)0.06

0.08

0.1

0.12

0.14

2 4 6 8 10 12 14 16

1/σ

dσ/

dχdi

jet

χdijet = exp(|y1−y2|)

Rutherford Scattering QCD New Physics

→ Good description of data by NLO QCD over whole→ M jj range ( from 0.25 to above 1.1 TeV )

→ Dijet invariant mass: good agreement in central→ rapidity region: PDF uncertainty



DØ (Lee Sawyer)

• Jet production dominant at hadron colliders → highest reach in energy and• probe of hard interactions at shortest distances• → three-jet production useful to test SM and search for new phy sics• → first multi-jet cross-section measurements at TeVatron

→ Reasonable agreement between data and NLO predictions for→ three-jet cross sections



DØ (Lars Sonnenschein)



H1 (Roman Kogler)

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ZEUS: inclusive-jet cross sections

ZEUS

10-3

10-2

10-1

1

10

10 2ZEUS (prel.) 189 pb-1

NLO (GRV-HO)

-1 < η jet < 2.5

Q2 < 1 GeV2

0.2 < y < 0.85

jet energy scale uncertainty

theoretical uncertainty

dσ/

dEje

t T

(pb/

GeV

)

-1

-0.5

0

0.5

20 30 40 50 60 70 80 90

Ejet

T (GeV)

rel.

diff

. to

NL

O ZEUS

10-4

10-3

10-2

10-1

1 ZEUS (prel.) 300 pb-1

NLO hadr Z0⊗ ⊗

EjetT,B > 8 GeV

-2 < ηB jet < 1.5

|cos γh| < 0.65

jet energy scale uncertainty

theoretical uncertainty d

σ/dQ

2 (pb

/GeV

2 )

-0.4

-0.2

0

0.2

0.4

102

103

104

Q2 (GeV2)

rel.

diff

. to

NL

O

→ Very precise data→ → stringent tests of pQCD from Q2 ≈ 0 to ≈ 20 000 GeV2

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(Denys Lontkovskyi) (Claudia Glasman)



ZEUS (Claudia Glasman) ��

∗ Vy∗ Vy∗ Vy

∗ Vy∗ Vy

∗ Vy∗ Vy∗ Vy∗ Vy∗ Vy∗ Vy∗ Vy

∗ Precise values of∗ αs(MZ) extracted∗ from jet production

th. uncert.

exp. uncert.

World average 2009

(S. Bethke, Eur Phys J C64 (2009) 689)

HERA average 2004

(C. Glasman, hep-ex/0506035)

HERA combined 2007

(H1prelim-07-132/ZEUS-prel-07-025)

Inclusive-jet cross sections in γp

ZEUS (Phys Lett B 560 (2003) 7)

Inclusive jet cross sections in NC DIS

ZEUS (Phys Lett B 649 (2007) 12)

Inclusive-jet cross sections in NC DIS (anti-kT)

ZEUS (DESY-10-034)

Inclusive-jet cross sections in NC DIS (SIScone)

ZEUS (DESY-10-034)

Inclusive-jet cross sections in NC DIS

ZEUS-prel-10-002

Inclusive-jet cross sections in γp

ZEUS-prel-10-003

0.1 0.12 0.14αs(MZ)

VyVyVyVyVyVyVyVyVyVyVy

Precise determination of the running of αs over a wide range in the scale

10 20 30 40 50 60 70

ZEUS (prel.)

NC DIS 300 pb-1

corr. uncert. th. uncert.

photoproduction 189 pb-1

corr. uncert. th. uncert.

QCD

Ejet

T (GeV)

α sZEUS

0.12

0.14

0.16

0.18

0.20

0.22 a

VyVyVyVyVyVyVyVyVyVyVyVyVyVyVy

⋆ Precise test of the⋆ performance of the⋆ kT , anti- kT and⋆ SIScone algorithms

ZEUS

0.9

1

1.1

rati

o to

kT

0.9

1

1.1

0.9

1

1.1

5 10 15 20 25 30 35 40 45 50 55

EjetT,B (GeV)ra

tio

to S

ISco

ne

anti-kT

SIScone

anti-kT

O(αs3) hadr Z0⊗ ⊗

ZEUS

0.9

1

1.1

rati

o to

kT

0.9

1

1.1

0.9

1

1.1

102

103

104

Q2 (GeV2)rati

o to

SIS

cone

anti-kT

SIScone

anti-kT

O(αs3) hadr Z0⊗ ⊗

# Precise new jet measurements will help to constrain further the proton PDFs


QCD @ the energy frontier......the future is already here!!!


LHCb (Manuel Schiller)



CMS (Krisztian Krajczar)



ALICE (Silvia Masciocchi)

• Measure the global characteristics of hadron collisions• → interactions dominated by soft processes• → study QCD in non-perturbative regime• → constrain phenomenological models• → give input to event generators

→ Increase in charged particle multiplicity with energy FAST ER than→ in any model considered



ATLAS (Heather Gray)

• First collisions recorded by ATLAS at√

s = 7 TeV on March 30

energy dependence of chargedparticle multiplicity

〈pT 〉 vs charged particle multiplicity

[GeV]s

210 310 410

η /

dch

N d⋅

evN

1/

0.5

1

1.5

2

2.5

3

3.5 1≥ chn = 0, η > 500 MeV,

TpATLAS Preliminary

PYTHIA ATLAS MC09PYTHIA DWPYTHIA Perugia0Data

[ G

eV ]

⟩T

p⟨

0.6

0.8

1

1.2

1.4

1.6 1≥ chn | < 2.5, η > 500 MeV, |

Tp

DataPYTHIA ATLAS MC09PYTHIA ATLAS MC09cPYTHIA DWPYTHIA Perugia0PHOJET

[ G

eV ]

⟩T

p⟨

0.6

0.8

1

1.2

1.4

1.6

ATLAS Preliminary = 7 TeVs

chn10 20 30 40 50 60 70 80 90

Rat

io

0.8

0.9

1

1.1

Data UncertaintiesMC / Data

chn10 20 30 40 50 60 70 80 90

Rat

io

0.8

0.9

1

1.1

→ None of the models describe the data → further tuning needed→ More than 400 µb−1 already delivered at

√s = 7 TeV



The present of QCD and... ...the future

World average 2009 (S. Bethke, Eur Phys J C64 (2009) 689)

NNLA+NNLO event shape dist. G. Luisoni et. al.

NNLO event shape moments and power corr. G. Luisoni et. al.

NNLO three-jet rate G. Luisoni et. al.

N3LL with power corr. V. Mateu et. al.

Multi-jet cross sections at low Q2

H1 Collab. (R. Kogler)

Multi-jet cross sections at high Q2

H1 Collab. (R. Kogler)

Inclusive-jet cross section in ppbar D0 Collab. (L. Sonnenschein)

Inclusive-jet cross sections in NC DIS ZEUS Collab. (C. Glasman)

Inclusive-jet cross sections in NC DIS (anti-kT) ZEUS Collab, (C. Glasman)

Inclusive-jet cross sections in NC DIS (SIScone) ZEUS Collab. (C. Glasman)

Inclusive-jet cross sections in NC DIS ZEUS Collab. (C. Glasman)

Inclusive-jet cross sections in γp ZEUS Collab. (D. Lontkovskyi)

0.1 0.12 0.14

αs(MZ)

We thank all the experimental speakers and hope to see you again in DIS2011 !!!Stefan & Claudia


dis 2010 xviii international workshop on deep-inelastic … · 2018. 11. 18. · dis 2010 xviii...

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