QCD Back-Scattering Photons in Relativistic Heavy ion Collisions

Printed in India. High energy photons created from back-scattering of jets in quark gluon plasma are considered a valuable probe of the temperature of the plasma, and of the energy loss mechanism of quarks in the plasma. An unambiguous identification of this source through the measurement of single inclusive photon spectra and photon azimuthal anisotropies has not been conclusive so far. We proposed a method to identify this source by using the correlation with away-side trigger jet at large momentum. We estimate the spectra and nuclear modification factor of back-scattering photons in coincidence with trigger jets for the heavy ion collisions at the Large Hadron Collider (LHC) energy. We find the back-scattering photons cause a promising peak in nuclear modification factor which smears out by including trigger jet energy loss. Thus separating back-scattering photons from other photon sources using trigger jets depends crucially on our ability to estimate the initial trigger jet energy in experiment.

QCD Back-Scattering Photons in Relativistic Heavy ion Collisions Conference Paper