Speaker
Pasquale Musella
(LIP Laboratorio de Instrumentaco e Fisica Experimental de Particulas)
Description
The measurement of inclusive photon production is a crucial step for the understanding of Standard Model Physics at the Large Hadron Collider (LHC) and an important prerequisite for many new physics searches. The identification of photons' experimental signatures and their discrimination against instrumental background is a challenging task in the severe LHC environment. We present a technique to extract the content of true isolated photons in an inclusive sample based on the study of electromagnetic shower deposits. The technique is applied to proton-proton collision events at sqrt(s) = 7TeV recorded by the Compact Muon Solenoid (CMS) detector and the isolated photon spectrum is extracted. Various sources of systematic uncertainties are studied in detail.
Determination of the cross section of photon+jet and diphoton production are important tests of standard model physics. In addition, they are significant backgrounds to Higgs di-photon searches. We demonstrate the use of a linear fisher discriminant to determine the purity of photons in pp -> photon+jet events with CMS at sqrt(s) = 7 TeV. It is based on a minimal number of isolation and cluster shape variables to reduce uncertainty in this small, early dataset. Finally, readiness for the diphoton cross section measurement is shown by the comparison, for key kinematical distributions, of proton-proton collisions events at sqrt(s) = 7 TeV with Monte Carlo simulations.
Authors
Bolek Wyslouch
(CMS)
Manfred Krammer
(CMS)
