Rivet analyses
Measurement of the mass dependence of the transverse momentum of lepton pairs in Drell–Yan production in proton-proton collisions at 13 TeV
Experiment: CMS (LHC)
Inspire ID: 2079374
Status: VALIDATED
Authors: - cms-pag-conveners-smp@cern.ch - Louis Moureaux - Buğra Bilin - Itana Bubanja - Philippe Gras
References: - Expt page: CMS-SMP-20-003 - arXiv: 2205.04897 - Submitted to Eur. Phys. J. C
Beams: p+ p+
Beam energies: (6500.0, 6500.0)GeV
Run details: - Run MC generators with Z decaying leptonically into both electrons and muons at 13 TeV CoM energy. If only one of the two decay channels is included, set LMODE accordingly.
The double differential cross sections of the Drell-Yan lepton pair (ℓ+ℓ−, dielectron or dimuon) production are measured, as functions of the invariant mass mℓℓ, transverse momentum pTℓℓ, and φη*. The φη* observable, derived from angular measurements of the leptons and highly correlated with pTℓℓ, is used to probe the low-pTℓℓ region in a complementary way. Dilepton masses up to 1 TeV are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various mℓℓ ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3 fb−1 of proton-proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 TeV. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.
Source
code:CMS_2022_I2079374.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/LeptonFinder.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
namespace Rivet {
/// @brief Z pT over a wide mass range
class CMS_2022_I2079374 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2022_I2079374);
/// Book histograms and initialise projections before the run
void init() {
// Get options from the new option system
// default to combined.
_mode = 2;
if (getOption("LMODE") == "EL") {
_mode = 0;
}
else if (getOption("LMODE") == "MU") {
_mode = 1;
}
else if (getOption("LMODE") == "EMU") {
_mode = 2;
}
else {
MSG_INFO("Assuming a mixed electron/muon sample. Set LMODE=EL/MU if your sample contains a single "
"flavor.");
}
FinalState fs;
PromptFinalState pfs(fs);
PromptFinalState bareMuons(Cuts::abspid == PID::MUON);
declare(LeptonFinder(bareMuons, pfs, 0.1, Cuts::abseta < 2.4 && Cuts::pT > 20 * GeV), "muons");
PromptFinalState bareElectrons(Cuts::abspid == PID::ELECTRON);
declare(LeptonFinder(bareElectrons, pfs, 0.1, Cuts::abseta < 2.4 && Cuts::pT > 20 * GeV), "electrons");
FastJets jets(fs, JetAlg::ANTIKT, 0.4);
declare(jets, "jets");
// Histograms
book(_pt_0jet_mass50_76, 1, 1, 1);
book(_pt_0jet_mass76_106, 3, 1, 1);
book(_pt_0jet_mass106_170, 5, 1, 1);
book(_pt_0jet_mass170_350, 7, 1, 1);
book(_pt_0jet_mass350_1000, 9, 1, 1);
book(_pt_1jet_mass50_76, 11, 1, 1);
book(_pt_1jet_mass76_106, 13, 1, 1);
book(_pt_1jet_mass106_170, 15, 1, 1);
book(_pt_1jet_mass170_350, 17, 1, 1);
book(_phistar_mass50_76, 19, 1, 1);
book(_phistar_mass76_106, 21, 1, 1);
book(_phistar_mass106_170, 23, 1, 1);
book(_phistar_mass170_350, 25, 1, 1);
book(_phistar_mass350_1000, 27, 1, 1);
}
/// Z boson finder.
/// Note: we don't use the standard DileptonFinder class in order to stick to
/// the definition of the publication that is simpler than the DileptonFinder
/// algorithm
/// @param leptons pt-ordered of electron or muon collection to use to build
/// the Z boson
std::unique_ptr<Particle> zfinder(const DressedLeptons& leptons) {
if (leptons.size() < 2) {
return nullptr;
}
// Leading lepton pT cut
if (leptons[0].pT() < 25. * GeV) {
return nullptr;
}
if (leptons[0].charge() * leptons[1].charge() > 0) {
return nullptr;
}
std::unique_ptr<Particle> candidate(new Particle(PID::ZBOSON, leptons[0].mom() + leptons[1].mom()));
if (candidate->mass() < 50 * GeV || candidate->mass() > 1000 * GeV) {
return nullptr;
}
return candidate;
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Fetch dressed leptons
auto muons = apply<LeptonFinder>(event, "muons").dressedLeptons();
auto electrons = apply<LeptonFinder>(event, "electrons").dressedLeptons();
const DressedLeptons* dressedLeptons = nullptr;
//Look for Z->ee
std::unique_ptr<Particle> z = zfinder(electrons);
if (z != nullptr) {
dressedLeptons = &electrons;
if (_mode == 1) {
// Z->ee found, but running with LMODE=MU
vetoEvent;
}
}
else if (_mode == 0) {
// LMODE=EL, but no Z->ee found
vetoEvent;
}
else { //look for Z->mumu
z = zfinder(muons);
if (z.get() != nullptr) {
dressedLeptons = &muons;
}
else { //no Z boson found
vetoEvent;
}
}
// Cluster jets
Jets jets = apply<FastJets>(event, "jets").jetsByPt(Cuts::absrap < 2.4 && Cuts::pT > 30 * GeV);
idiscardIfAnyDeltaRLess(jets, *dressedLeptons, 0.4);
//------------------------------------------------
// Compute phi*
const Particle& lminus = dressedLeptons->at(0).charge() < 0 ? dressedLeptons->at(0)
: dressedLeptons->at(1);
const Particle& lplus = dressedLeptons->at(0).charge() < 0 ? dressedLeptons->at(1)
: dressedLeptons->at(0);
double phi_acop = M_PI - deltaPhi(lminus, lplus);
double costhetastar = tanh(0.5 * (lminus.eta() - lplus.eta()));
double sin2thetastar = (costhetastar > 1) ? 0.0 : (1.0 - sqr(costhetastar));
double phistar = tan(0.5 * phi_acop) * sqrt(sin2thetastar);
if (z->mass() > 50. && z->mass() < 76.) {
_pt_0jet_mass50_76->fill(z->pT());
_phistar_mass50_76->fill(phistar);
}
else if (z->mass() > 76. && z->mass() < 106.) {
_pt_0jet_mass76_106->fill(z->pT());
_phistar_mass76_106->fill(phistar);
}
else if (z->mass() > 106. && z->mass() < 170.) {
_pt_0jet_mass106_170->fill(z->pT());
_phistar_mass106_170->fill(phistar);
}
else if (z->mass() > 170. && z->mass() < 350.) {
_pt_0jet_mass170_350->fill(z->pT());
_phistar_mass170_350->fill(phistar);
}
else if (z->mass() > 350. && z->mass() < 1000.) {
_pt_0jet_mass350_1000->fill(z->pT());
_phistar_mass350_1000->fill(phistar);
}
//---------------------- at least one jet --------------------------------
if (jets.size() < 1) {
return;
}
if (z->mass() > 50. && z->mass() < 76.) {
_pt_1jet_mass50_76->fill(z->pT());
}
else if (z->mass() > 76. && z->mass() < 106.) {
_pt_1jet_mass76_106->fill(z->pT());
}
else if (z->mass() > 106. && z->mass() < 170.) {
_pt_1jet_mass106_170->fill(z->pT());
}
else if (z->mass() > 170. && z->mass() < 350.) {
_pt_1jet_mass170_350->fill(z->pT());
}
}
/// Calculates the ratio between two histograms
void calculateRatio(int d, const Histo1DPtr& numerator, const Histo1DPtr& denominator) {
Estimate1DPtr ratio;
book(ratio, d, 1, 1);
// The denominator has a finer binning, so rebin it
auto rebinned_den = denominator->clone();
rebinned_den.rebinX(numerator->xEdges());
divide(*numerator, rebinned_den, ratio);
}
/// Normalise histograms etc., after the run
void finalize() {
double norm = (sumOfWeights() != 0) ? crossSection() / picobarn / sumOfWeights() : 1.0;
if (_mode == 2) {
norm /= 2.;
}
scale(_pt_0jet_mass50_76, norm);
scale(_pt_0jet_mass76_106, norm);
scale(_pt_0jet_mass106_170, norm);
scale(_pt_0jet_mass170_350, norm);
scale(_pt_0jet_mass350_1000, norm);
scale(_pt_1jet_mass50_76, norm);
scale(_pt_1jet_mass76_106, norm);
scale(_pt_1jet_mass106_170, norm);
scale(_pt_1jet_mass170_350, norm);
scale(_phistar_mass50_76, norm);
scale(_phistar_mass76_106, norm);
scale(_phistar_mass106_170, norm);
scale(_phistar_mass170_350, norm);
scale(_phistar_mass350_1000, norm);
// Calculate the ratios
calculateRatio(29, _pt_0jet_mass50_76, _pt_0jet_mass76_106);
calculateRatio(31, _pt_0jet_mass106_170, _pt_0jet_mass76_106);
calculateRatio(33, _pt_0jet_mass170_350, _pt_0jet_mass76_106);
calculateRatio(35, _pt_0jet_mass350_1000, _pt_0jet_mass76_106);
calculateRatio(37, _pt_1jet_mass50_76, _pt_1jet_mass76_106);
calculateRatio(39, _pt_1jet_mass106_170, _pt_1jet_mass76_106);
calculateRatio(41, _pt_1jet_mass170_350, _pt_1jet_mass76_106);
calculateRatio(43, _phistar_mass50_76, _phistar_mass76_106);
calculateRatio(45, _phistar_mass106_170, _phistar_mass76_106);
calculateRatio(47, _phistar_mass170_350, _phistar_mass76_106);
calculateRatio(49, _phistar_mass350_1000, _phistar_mass76_106);
}
protected:
size_t _mode;
private:
/// @name Histograms
Histo1DPtr _pt_0jet_mass50_76, _pt_0jet_mass76_106, _pt_0jet_mass106_170, _pt_0jet_mass170_350,
_pt_0jet_mass350_1000;
Histo1DPtr _pt_1jet_mass50_76, _pt_1jet_mass76_106, _pt_1jet_mass106_170, _pt_1jet_mass170_350;
Histo1DPtr _phistar_mass50_76, _phistar_mass76_106, _phistar_mass106_170, _phistar_mass170_350,
_phistar_mass350_1000;
};
RIVET_DECLARE_PLUGIN(CMS_2022_I2079374);
}