Rivet analyses
title: ATLAS_2015_I1408516
$Z$ $p_T$ and $Z$ $\phi^*$
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 $p_\text{T}^{\ell\ell}$ and the angular variable $\phi^\ast_\eta$ of Drell-Yan lepton pairs are measured in $20.3\,\text{fb}^{-1}$ 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
```c++
include "Rivet/Analysis.hh"
include "Rivet/Projections/DileptonFinder.hh"
include "Rivet/Projections/FinalState.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);
} ```