Separation of quark and gluon jets in the direct photon production processes at the LHC using the neural network approach

A neural network technique is used to discriminate between quark and gluon jets produced in the qg->q+photon and q q->g+photon processes at the LHC. Considering the network as a trigger and using the PYTHIA event generator and the full event fast simulation package for the CMS detector CMSJET we obtain signal-to-background ratios.Comment: 22 pages, uses cernrep.cls style fil

Jet energy scale setting with "photon+Jet" events at LHC energies. Selection of events with a clean "photon+Jet" topology and photon Pt - jet Pt disbalance

It is shown in the paper that Pt activity limitation (modulus of the vector sum) of all particle beyond "photon+Jet" system Pt^out leads to the noticeable photon Pt - jet Pt disbalance decreasing. On a simultaneous restriction of the cluster Pt and Pt^out from above it is possible to reach an acceptable balance between photon Pt - jet Pt with a sufficient number of the photon Pt - jet Pt events for the jet energy scale setting and hadron calorimeter calibratiom of the CMS detector at LHC.Comment: 7 pages, 7 figures, uses cernrep.cls style fil

On the possibility of discrimination between π0,η,ω,Ks0\pi^0, \eta, \omega, K^0_s mesons and a photon based on the calorimeter information in the CMS detector

The possibility of separating the $\pi^0, \eta, \omega$ and $K^0_s$ meson background from the signal photons produced directly in $pp$ collisions is analyzed. The rejection factors for two pseudorapidity regions 0.4<\eta<1.0$and 1.6<\eta<2.0$ and six Et values, 20, 40, 60, 80, 100 and 200 GeV, are calculated for a case when only the calorimeter information is used. The cases of $\eta, \omega$ and $K^0_s$ mesons decaying through the neutral and charged channels are considered separately.Comment: 17 pages, uses cernrep.cls style fil

"photon+Jet" events rate estimation for gluon distribution determination at LHC

It is shown that "photon+Jet" events, being collected at LHC, would provide us with the data sufficient for an extraction of gluon distribution function in a proton using valence and s quark distributions measured in the same experiment with another physical proces A new region of 10^{-4}< x < 10^{-1} with 1.6x10^3 photon +Jet events are also given.Comment: 9 pages, 1 figure, modified cernrep.cls fil