A study of final-state radiation in decays of Z bosons produced in pp collisions at 7 TeV

Understand

The differential cross sections for the production of photons in Z to mu+ mu- gamma decays are presented as a function of the transverse energy of the photon and its separation from the nearest muon.

• The data for these measurements were collected with the CMS detector and correspond to an integrated luminosity of 4.7 inverse femtobarns of pp collisions at sqrt(s) = 7 TeV delivered by the CERN LHC.
• The cross sections are compared to simulations with POWHEG and PYTHIA, where PYTHIA is used to simulate parton showers and final-state photons.
• These simulations match the data to better than 5%.