20-27 July 2011
Alpes Congrès - Alpexpo
Europe/Paris timezone

Azimuthal decorrelations and multiple parton interactions in $\boldsymbol{\gamma+{\rm 2~jet}}$ and $\boldsymbol{\gamma+{\rm 3~jet}}$ events in $\boldsymbol{p\bar{p}}$ collisions at $\boldsymbol{\sqrt{s}=1.96}$~TeV

23 Jul 2011, 10:00
Bayard (Alpes Congrès - Alpexpo)


Alpes Congrès - Alpexpo

Parallel session talk QCD QCD


Prof. Nikolay SKACHKOV (Joint Institute for Nuclear Research)


Samples of inclusive $\gamma+{\rm 2~jet}$ and $\gamma+{\rm 3~jet}$ events collected by the D0 experiment with an integrated luminosity of about 1~fb$^{-1}$ in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV are used to measure cross sections as a function of the angle in the plane transverse to the beam direction between the transverse momentum ($p_T$) of the $\gamma+$leading jet system (jets are ordered in $p_T$) and $p_T$ of the other jet for $\gamma+{\rm 2~jet}$, or $p_T$ sum of the two other jets for $\gamma+{\rm 3~jet}$ events. The results are compared to different models of multiple parton interactions (MPI) in the {\sc pythia} and {\sc sherpa} Monte Carlo (MC) generators. The data indicate a contribution from events with double parton (DP) interactions and are well described by predictions provided by the {\sc pythia} MPI models with $p_T$-ordered showers and by {\sc sherpa} with the default MPI model. The $\gamma+{\rm 2~jet}$ data are also used to determine the fraction of events with DP interactions as a function of the azimuthal angle and as a function of the second jet $p_T$.

Primary author

Dr Marco Verzocchi (Fermilab - PPD Division)

Presentation Materials