Jul 16 – 22, 2009
Kraków, Poland
Europe/Warsaw timezone

Preliminary Results on Multiple Parton Interactions from HERA and TEVATRON

Jul 16, 2009, 12:10 PM
20m
Exhibition room A (Kraków, Poland)

Exhibition room A

Kraków, Poland

The Auditorium Maximum of the Jagiellonian University 33 Krupnicza Street 31-123 Kraków
QCD at Colliders V. QCD at Colliders

Speaker

Prof. D0 H1 (DESY, FNAL)

Description

Photoproduction data of HERA are analyzed by requiring dijets with transverse momenta of at least 5 GeV. The two jets define in azimuth a towards region (leading jet) and an away region (2nd jet) and transverse regions between them. The charged particle multiplicity is measured in these regions as a function of the variables x_{gamma} and pT_{leading jet}. Models which include contributions of multiparton interactions are able to describe the measurement, whereas predictions without them lie below the measurements, especially at low x_{gamma}, the region of enhanced contributions from the resolved photon. Double parton (DP) interactions in “gamma + 3 jet” events in p-pbar collisions at sqrt{s}=1.96TeV are studied basing on the sample of “gamma + 3jet” events collected in the D0 experiment with an integrated luminosity of 1fb^{-1}. The fraction f{DP} of the events with double parton scattering is determined. The events are selected with photon candidate transverse momentum 60 < pT^{gamma} < 80 GeV. The leading jet pT ^{jet} > 25 GeV and two additional jets with pT > 15 GeV. The values of f{DP} are measured in three intervals of the transverse momentum pT^{jet2} of the second jet which spans the range of 15 - 30 GeV. It is found that the f{DP}fractions drop with increasing of pT^{jet2}. The effective cross section sigma_{eff} (a process-independent parameter which contains an information about the parton density inside the proton and about the parton correlations) is calculated in the same three pT^{jet2} intervals. The average value over these three pT^{jet2} intervals is sigma_{eff}^{aver} = 15.1 +/- 1.9 mb.

Primary author

Prof. D0 H1 (DESY, FNAL)

Presentation materials