JetWeight

Description

Calculate the jet weight from the b-tagging calibration following the BTV recommendations.

Collaboration diagram for JetWeight:

Public Member Functions
	JetWeight (const fs::path &SFtables, const fs::path &fDisc)
double	operator() (const RecJet &jet)

Public Attributes
BTagCalibrationReader	loose
BTagCalibrationReader	medium
BTagCalibrationReader	tight
unique_ptr< TH3 >	discriminant

Constructor & Destructor Documentation

JetWeight()

JetWeight ( const fs::path &  SFtables, const fs::path &  fDisc  )

inline

Prepares the objects to retrieve the SFs from the SF tables and the binned discriminant.

Parameters

SFtables	path to the CSV file (provided by BTV)
fDisc	path to the ROOT file (calculated with DAS)

                 :
        loose (BTagEntry::OP_LOOSE , "central", {"up", "down"}),
        medium(BTagEntry::OP_MEDIUM, "central", {"up", "down"}),
        tight (BTagEntry::OP_TIGHT , "central", {"up", "down"})
    {
        cout << "Extracting binned discriminant from " << fDisc << endl;
        discriminant = DT::GetHist<TH3>({fDisc}, "discriminant");
        if (discriminant->GetNbinsZ() != 4) {
            const char * what = Form("Found %d working points (expecting 4)",
                                        discriminant->GetNbinsZ());
            BOOST_THROW_EXCEPTION( DE::BadInput(what, discriminant) );
        }
 
        cout << "Extracting scale factors from " << SFtables << endl;
        BTagCalibration calib("DeepJet", SFtables.c_str());
        for (BTagCalibrationReader * reader: {&loose, &medium, &tight}) {
            reader->load(calib, BTagEntry::FLAV_B   , "comb");
            reader->load(calib, BTagEntry::FLAV_C   , "comb");
            reader->load(calib, BTagEntry::FLAV_UDSG, "incl");
        }
    }

Member Function Documentation

operator()()

double operator() ( const RecJet &  jet )

inline

Takes the discriminat values, true flavour, and kinematics of a jet to calculate the jet weight.

Todo:

variation

Todo:

standardise flavour indices...

Todo:

variations

    {
        int ifl; 
        BTagEntry::JetFlavor fl;
             if (jet.nBHadrons > 0) { ifl = 5; fl = BTagEntry::FLAV_B;    }
        else if (jet.nCHadrons > 0) { ifl = 4; fl = BTagEntry::FLAV_C;    }
        else                        { ifl = 0; fl = BTagEntry::FLAV_UDSG; }
 
        const char * variation = "central"; 
 
        float pt = jet.CorrPt(),
              eta = abs(jet.p4.Eta());
 
        float disc = jet.DeepJet.B();
        int idisc = discriminant->GetZaxis()->FindBin(disc);
 
        if (idisc == 4) // above the tight WP
            return tight.eval_auto_bounds(variation, fl, eta, pt);
 
        int ipt = discriminant->GetXaxis()->FindBin(pt);
        double Nt = discriminant->GetBinContent(ipt, ifl, 4),
               Nm = discriminant->GetBinContent(ipt, ifl, 3);
        if (idisc == 3) { // above the medium WP
            double SFt = tight .eval_auto_bounds(variation, fl, eta, pt),
                   SFm = medium.eval_auto_bounds(variation, fl, eta, pt);
            return SFm + (Nt/Nm)*(SFm-SFt);
        }
 
        double Nl = discriminant->GetBinContent(ipt, ifl, 2);
        if (idisc == 2) { // above the loose WP
            double SFm = medium.eval_auto_bounds(variation, fl, eta, pt),
                   SFl = loose .eval_auto_bounds(variation, fl, eta, pt);
            return SFl + ((Nm+Nt)/Nl)*(SFl-SFm);
        }
 
        double Nn = discriminant->GetBinContent(ipt, ifl, 1),
               SFl = loose.eval_auto_bounds(variation, fl, eta, pt);
        return 1 + ((Nl+Nm+Nt)/Nn)*(1-SFl);
    }

Member Data Documentation

discriminant

unique_ptr<TH3> discriminant

in the same convention as in getBTagBinnedDiscriminant

loose

BTagCalibrationReader loose

medium

BTagCalibrationReader medium

tight

BTagCalibrationReader tight

object to call to get SFs

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The documentation for this struct was generated from the following file:

• /builds/cms-analysis/general/DasAnalysisSystem/Core/Installer/Core/BTagging/bin/applyBTagSF.cc