Fake Rate Definitions

High Pt Photon ID

Our photon identification variables and cuts use the High pT photon ID V2 working points.

Sigma_IphiIphi cut

In addition to the below object definitions, we apply a cut on sigma_IphiIphi to remove beam halo. This cut is applied offline as follows

if (Photon_sigmaIphiIphi5x5 < 0.009) continue;

See our discussion of beam halo rejection on the fake rate twiki: Rejection of Beam Halo in Jet Data Sample

Numerator object definition

We form a "relaxed numerator" compared to what we would get solely by using our photon ID. Since we will start by using sigma_iEtaiEta templates, this is the variable we choose to relax. Our numerator definition is the same ID as the High pT photon ID, but without any sigma_iEtaiEta cut.

In the code, we select numerator object candidates

photonInfo.isNumeratorObjCand = ExoDiPhotons::passNumeratorCandCut(photon,rho,isSat);

where

Finally, we select our numerator objects offline as

bool isNumeratorObj = Photon_isNumeratorObjCand && Photon_passChIso;

Denominator object definition

We form a "loose-but-not-tight" denominator. An object must pass

iso < min[5*(iso cut), 0.2*photon->pt()]

where "iso" is each isolation variable used in the High pT photon ID, of which there are two: charged hadron isolation and "corrected" photon isolation. In addition, we require the object to fail at least one of the High pT photon ID variables, except for the CSEV, which we require the object to pass.

In the code, we select denominator objects as

photonInfo.isDenominatorObj = ExoDiPhotons::passDenominatorCut(photon,rho,isSat);

where

The relaxed isolation cuts are

and

Real templates

Our real templates also come from selecting numerator objects

bool isNumeratorObj = Photon_isNumeratorObjCand && Photon_passChIso;

but are known real objects from MC.

Fake templates

Our fake templates come from numerator objects, but only those that fall into a certain side band of the charged hadron isolation variable. Offline we select

bool isFakeTemplateObj = Photon_isNumeratorObjCand && inChIsoSideband;

where

bool inChIsoSideband = (10. < Photon_chargedHadIso03) && (Photon_chargedHadIso03 < 15.);

Sigma_iEtaiEta

Since sigma_iEtaiEta isn't used in the numerator but is one of the ID-vetos in the denominator, it's possible for an object to end up in both our numerator and denominator definitions.

Our code

https://github.com/cms-exotica-diphotons/diphoton-analysis/blob/master/CommonClasses/interface/PhotonID.h

-- AndrewBuccilli - 2016-03-07