Measurements of inclusive and exclusive particle production at ZEUS

Measurements of inclusive and Measurements of inclusive and exclusive particle production at exclusive particle production at

ZEUSZEUS Igor Kadenko,Igor Kadenko,

Taras Shevchenko National University ofTaras Shevchenko National University of Kyiv Kyiv Department of Nuclear PhysicsDepartment of Nuclear Physics

(on behalf of the ZEUS Collaboration)(on behalf of the ZEUS Collaboration)

18.09.2010 Particle production at ZEUS 2

OutlineOutline

• Particle production in high energy electron proton Particle production in high energy electron proton scattering.scattering.

• Experimental setup: HERA accelerator and ZEUS Experimental setup: HERA accelerator and ZEUS detector.detector.

• Charged particles production in:Charged particles production in:

- deep inelastic scattering (DIS);deep inelastic scattering (DIS);

- photo-production.photo-production.

• Production of identified neutral particles.Production of identified neutral particles.

• Exclusive production: di-pion diffractive electro-Exclusive production: di-pion diffractive electro-production.production.

• Conclusions.Conclusions.


Particle production in high energy electron-Particle production in high energy electron-

proton scatteringproton scattering

Most of the interactions (Most of the interactions (~~90%) 90%) are the photo productionare the photo production


Measurement of scaled momentum Measurement of scaled momentum distributions xdistributions xpp as a test of QCDas a test of QCD



HERAHERA


I. Charged particle production in neutral I. Charged particle production in neutral current DIScurrent DIS



The number of charged particles per The number of charged particles per event as a function of Q in xevent as a function of Q in xpp bins bins

The number of charged particles per The number of charged particles per event as a function of Qevent as a function of Q2 2 in xin xpp bins bins

DESY-09-229



The number of charged particles per event as a function of QThe number of charged particles per event as a function of Q22 in xin xpp bins bins

DESY-09-229

LO calculationLO calculation NLO calculationNLO calculation




II. Scaled momentum distributions of II. Scaled momentum distributions of charged particles for dijet photoproductioncharged particles for dijet photoproduction

DESY-09-059



DESY-09-059



The The ξ ξ -distribution in five E-distribution in five Ejetjet bins bins ΛΛeff eff extracted at five Eextracted at five Ejetjet points points

DESY-09-059



•The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD)

DESY-09-059


III. III. Scaled momentum distributions of Scaled momentum distributions of identified particles, Kidentified particles, K00

s s and and ΛΛ

Scaled momentum distributions for Scaled momentum distributions for KK00

ss vs. Q vs. Q2 2 in different regions of xin different regions of xpp

Scaled momentum distributions for Scaled momentum distributions for ΛΛ vs Q vs Q22 in different regions of x in different regions of xpp

ZEUS-prel-10-013


III. Scaled momentum distributions of III. Scaled momentum distributions of identified particles, Kidentified particles, K00

ss and and ΛΛ

Scaled momentum distributions for Scaled momentum distributions for KK00

ss vs. x vs. xpp in different regions of Q in different regions of Q22 Scaled momentum distributions for Scaled momentum distributions for ΛΛ vs. x vs. xpp in different regions of Q in different regions of Q22

ZEUS-prel-10-013


IV. Dipion diffractive electro-productionIV. Dipion diffractive electro-production

Data are good described by pion form factorData are good described by pion form factor



Good agreement between ZEUS (preliminary) results and PDG.Good agreement between ZEUS (preliminary) results and PDG.Reasonable values of the relative amplitudes are obtained.Reasonable values of the relative amplitudes are obtained.




ConclusionsConclusions• Charged particle spectra have been measured in DIS and Charged particle spectra have been measured in DIS and

photoproduction at HERA. In General results are found to photoproduction at HERA. In General results are found to support the concept of quark fragmentation universality. support the concept of quark fragmentation universality. However, in detail, there exists some issues when However, in detail, there exists some issues when comparing the data with theory.comparing the data with theory.

• Many new high statistics measurements of exclusive Many new high statistics measurements of exclusive Vector Mesons at HERA. The measurements allow us to Vector Mesons at HERA. The measurements allow us to study the transition from the soft to hard regime. The study the transition from the soft to hard regime. The perturbative QCD expectations in general are compatible perturbative QCD expectations in general are compatible with the data. The different models describe main with the data. The different models describe main features, but differ in some details. The measurements features, but differ in some details. The measurements provide new insight into the proton structure with a high provide new insight into the proton structure with a high sensitivity to gluon density, skewing effects and GPDs.sensitivity to gluon density, skewing effects and GPDs.

• The measured in LAB and the Breit frame production The measured in LAB and the Breit frame production cross sections of neutral strange hadrons in general are cross sections of neutral strange hadrons in general are in good agreement with predictions of two MC: MEPS and in good agreement with predictions of two MC: MEPS and CDM when applying model parameters with lambda_s = CDM when applying model parameters with lambda_s = 0.286 as used at LEP.0.286 as used at LEP.

Date post:	03-Jan-2016
Category:	Documents
Upload:	celerina-andeana
View:	25 times
Download:	2 times

Measurements of inclusive and exclusive particle production at ZEUS

Documents