by the requirements on the photon kinematic variables and isolation. Differential cross sections are measured as functions of several observables, describing the properties of the diphoton system and of ( quark) jets, leptons, and missing transverse momentum accompanying the diphoton system. A double-differential cross section measurement is also performed as a function of the transverse momentum () of the diphoton system and the number of additional jets in the event. Cross section measurements are also performed in regions of the fiducial phase space. The regions are chosen to enhance the contribution of specific production mechanisms to the signal composition, based on the additional particles produced in association with the diphoton system and on the topology of the event.

The CMS detector {#sec:CMS}
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The central feature of the CMS apparatus is a superconducting solenoid of 6 internal diameter, providing a magnetic field of 3.8. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadronic calorimeter (HCAL), each composed of a barrel and two endcap sections. Forward calorimeters extend the pseudorapidity ($\eta$) coverage provided by the barrel and endcap detectors. Muons are detected in gas-ionization chambers embedded 