Orateur
Prof.
Nikolay SKACHKOV
(Joint Institute for Nuclear Research)
Description
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 $p_T$.
Auteur principal
Dr
Marco Verzocchi
(Fermilab - PPD Division)
