Isolated photon production in $\sqrt{s_{NN}}$ = 2.76 TeV PbPb collisions as a function of transverse energy and reaction centrality

Understand

In studies of the dense medium produced in ultra-relativistic heavy ion collisions, photons are important hard probes, since they are not expected to be modified by the medium.

• The measurement of isolated prompt photon production in PbPb collisions provides a test of perturbative quantum chromodynamics (pQCD) and the information to constrain the nuclear parton distribution functions.
• CMS has shown photon purity measurement capabilities in pp collisions using the shower shape templates.
• In PbPb co llisions at CMS, this technique was applied for the first time in heavy ion collisions.