Rivet analyses
Z pT and Z ϕ*
Experiment: ATLAS (LHC)
Inspire ID: 1408516
Status: VALIDATED
Authors: - Christian Gutschow
References: - Expt page: ATLAS-STDM-2014-12 - arXiv: 1512.02192 - submitted to EPJC
Beams: p+ p+
Beam energies: (4000.0, 4000.0)GeV
Run details: - inclusive Z production in the electron channel
Distributions of transverse momentum pTℓℓ and the angular variable ϕη* of Drell-Yan lepton pairs are measured in 20.3 fb−1 of proton-proton collisions at $\sqrt{s}=8$,TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects. Compared to previous measurements in proton–proton collisions at $\sqrt{s}=7$ TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the Z-boson mass peak. Specify the lepton channel (default is Z->ee) by using the LMODE variable. Only individual channels are available as particle-level measurements.
Source
code:ATLAS_2015_I1408516.cc
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/DileptonFinder.hh"
namespace Rivet {
class ATLAS_2015_I1408516 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2015_I1408516);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Get options
_mode = 0;
if ( getOption("LMODE") == "EL" ) _mode = 0;
if ( getOption("LMODE") == "MU" ) _mode = 1;
// Configure projections
Cut cuts = Cuts::abseta < 2.4 && Cuts::pT > 20*GeV;
DileptonFinder zfinder(91.2*GeV, 0.1, cuts && Cuts::abspid == (_mode ? PID::MUON : PID::ELECTRON), Cuts::massIn(12*GeV, 150*GeV));
declare(zfinder, _mode ? "DileptonFinder_mu" : "DileptonFinder_el");
// Book histograms
const size_t offset = _mode ? 4 : 1;
book(_h["phistar_lo_00_08"] , 2, 1, offset);
book(_h["phistar_lo_08_16"] , 3, 1, offset);
book(_h["phistar_lo_16_24"] , 4, 1, offset);
book(_h["phistar_me_00_04"] , 5, 1, offset);
book(_h["phistar_me_04_08"] , 6, 1, offset);
book(_h["phistar_me_08_12"] , 7, 1, offset);
book(_h["phistar_me_12_16"] , 8, 1, offset);
book(_h["phistar_me_16_20"] , 9, 1, offset);
book(_h["phistar_me_20_24"] ,10, 1, offset);
book(_h["phistar_hi_00_08"] ,11, 1, offset);
book(_h["phistar_hi_08_16"] ,12, 1, offset);
book(_h["phistar_hi_16_24"] ,13, 1, offset);
book(_h["phistar_mll_46_66" ] ,14, 1, offset);
book(_h["phistar_mll_66_116" ] ,15, 1, offset);
book(_h["phistar_mll_116_150"] ,16, 1, offset);
book(_h["zpt_00_04"] ,17, 1, offset);
book(_h["zpt_04_08"] ,18, 1, offset);
book(_h["zpt_08_12"] ,19, 1, offset);
book(_h["zpt_12_16"] ,20, 1, offset);
book(_h["zpt_16_20"] ,21, 1, offset);
book(_h["zpt_20_24"] ,22, 1, offset);
book(_h["zpt_mll_12_20" ] ,23, 1, offset);
book(_h["zpt_mll_20_30" ] ,24, 1, offset);
book(_h["zpt_mll_30_46" ] ,25, 1, offset);
book(_h["zpt_mll_46_66" ] ,26, 1, offset);
book(_h["zpt_mll_66_116" ] ,27, 1, offset);
book(_h["zpt_mll_116_150"] ,28, 1, offset);
book(_h["zpt_00_04_xsec"] ,29, 1, offset);
book(_h["zpt_04_08_xsec"] ,30, 1, offset);
book(_h["zpt_08_12_xsec"] ,31, 1, offset);
book(_h["zpt_12_16_xsec"] ,32, 1, offset);
book(_h["zpt_16_20_xsec"] ,33, 1, offset);
book(_h["zpt_20_24_xsec"] ,34, 1, offset);
book(_h["zpt_mll_12_20_xsec" ] ,35, 1, offset);
book(_h["zpt_mll_20_30_xsec" ] ,36, 1, offset);
book(_h["zpt_mll_30_46_xsec" ] ,37, 1, offset);
book(_h["zpt_mll_46_66_xsec" ] ,38, 1, offset);
book(_h["zpt_mll_66_116_xsec" ] ,39, 1, offset);
book(_h["zpt_mll_116_150_xsec"] ,40, 1, offset);
book(_h["mll_xsec"] ,41, 1, 1 + _mode);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Get leptonic Z boson
const DileptonFinder& zfinder = apply<DileptonFinder>(event, _mode ? "DileptonFinder_mu" : "DileptonFinder_el");
if (zfinder.bosons().size() != 1 ) vetoEvent;
const Particle& Zboson = zfinder.boson();
// Get/cut on heavily used Z boson properties
const double zpt = Zboson.pT();
const double zrap = Zboson.absrap();
const double zmass = Zboson.mass();
if (zrap > 2.4) vetoEvent;
// Get/cut on Z boson leptons
const Particles& leptons = zfinder.constituents();
if (leptons.size() != 2 || leptons[0].charge3() * leptons[1].charge3() > 0) vetoEvent;
const Particle& lminus = leptons[0].charge() < 0 ? leptons[0] : leptons[1];
const Particle& lplus = leptons[0].charge() < 0 ? leptons[1] : leptons[0];
// Compute phi*
const double phi_acop = M_PI - deltaPhi(lminus, lplus);
const double costhetastar = tanh( 0.5 * (lminus.eta() - lplus.eta()) );
const double sin2thetastar = (costhetastar > 1) ? 0.0 : (1.0 - sqr(costhetastar));
const double phistar = tan(0.5 * phi_acop) * sqrt(sin2thetastar);
// Inclusive mll
if (zmass > 46*GeV || zpt > 45*GeV) {
// 46 GeV < mll < 150 GeV OR (12 GeV < mll < 46 GeV AND ZpT >45 GeV)
_h["mll_xsec"]->fill(zmass);
}
// 12 GeV < mll < 150 GeV observables
if (zmass < 20*GeV) {
// 12 GeV < mll < 20 GeV
if (zpt > 45*GeV) { // ZpT cut only for low-mass regions
_h["zpt_mll_12_20_xsec"]->fill(zpt);
_h["zpt_mll_12_20" ]->fill(zpt);
}
} else if (zmass < 30*GeV) {
// 20 GeV < mll < 30 GeV
if (zpt > 45*GeV) { // ZpT cut only for low-mass regions
_h["zpt_mll_20_30_xsec"]->fill(zpt);
_h["zpt_mll_20_30" ]->fill(zpt);
}
} else if (zmass < 46*GeV) {
// 30 GeV < mll < 46 GeV
if (zpt > 45*GeV) { // ZpT cut only for low-mass regions
_h["zpt_mll_30_46_xsec"]->fill(zpt);
_h["zpt_mll_30_46" ]->fill(zpt);
}
} else if (zmass < 66*GeV) {
// 46 GeV < mll < 66 GeV
_h["zpt_mll_46_66_xsec"]->fill(zpt);
_h["zpt_mll_46_66" ]->fill(zpt);
_h["phistar_mll_46_66"]->fill(phistar);
if (zrap < 0.8) _h["phistar_lo_00_08"]->fill(phistar);
else if (zrap < 1.6) _h["phistar_lo_08_16"]->fill(phistar);
else _h["phistar_lo_16_24"]->fill(phistar);
} else if (zmass < 116*GeV) {
// 66 GeV < mll < 116 GeV
_h["zpt_mll_66_116_xsec"]->fill(zpt);
_h["zpt_mll_66_116" ]->fill(zpt);
if (zrap < 0.4) {
_h["zpt_00_04_xsec"]->fill(zpt);
_h["zpt_00_04"]->fill(zpt);
} else if (zrap < 0.8) {
_h["zpt_04_08_xsec"]->fill(zpt);
_h["zpt_04_08"]->fill(zpt);
} else if (zrap < 1.2) {
_h["zpt_08_12_xsec"]->fill(zpt);
_h["zpt_08_12"]->fill(zpt);
} else if (zrap < 1.6) {
_h["zpt_12_16_xsec"]->fill(zpt);
_h["zpt_12_16"]->fill(zpt);
} else if (zrap < 2.0) {
_h["zpt_16_20_xsec"]->fill(zpt);
_h["zpt_16_20"]->fill(zpt);
} else {
_h["zpt_20_24_xsec"]->fill(zpt);
_h["zpt_20_24"]->fill(zpt);
}
_h["phistar_mll_66_116"]->fill(phistar);
if (zrap < 0.4) _h["phistar_me_00_04"]->fill(phistar);
else if (zrap < 0.8) _h["phistar_me_04_08"]->fill(phistar);
else if (zrap < 1.2) _h["phistar_me_08_12"]->fill(phistar);
else if (zrap < 1.6) _h["phistar_me_12_16"]->fill(phistar);
else if (zrap < 2.0) _h["phistar_me_16_20"]->fill(phistar);
else _h["phistar_me_20_24"]->fill(phistar);
} else {
// 116 GeV < mll < 150 GeV
_h["zpt_mll_116_150_xsec"]->fill(zpt);
_h["zpt_mll_116_150" ]->fill(zpt);
_h["phistar_mll_116_150"]->fill(phistar);
if (zrap < 0.8) _h["phistar_hi_00_08"]->fill(phistar);
else if (zrap < 1.6) _h["phistar_hi_08_16"]->fill(phistar);
else _h["phistar_hi_16_24"]->fill(phistar);
}
}
/// Normalise histograms etc., after the run
void finalize() {
// Scale non-xsec plots to cross-section
const double sf = crossSection() / picobarn / sumOfWeights();
for (auto& key_hist : _h) {
scale(key_hist.second, sf);
if (!contains(key_hist.first, "_xsec")) normalize(key_hist.second);
}
// M(ll) plot isn't a differential cross section so shouldn't be divided by bin width
for (size_t i = 1; i < 7; ++i) {
double bw = _h["mll_xsec"]->bin(i).xWidth();
_h["mll_xsec"]->bin(i).scaleW(bw);
}
}
/// @}
protected:
size_t _mode;
private:
/// @name Histograms
/// @{
map<string, Histo1DPtr> _h;
/// @}
};
RIVET_DECLARE_PLUGIN(ATLAS_2015_I1408516);
}