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Rivet analyses reference
ATLAS_2018_I1615866
Exclusive photon-photon production of muon pairs in proton-proton collisions at $\sqrt{s} = 13$ TeV
Experiment: ATLAS (LHC)
Inspire ID: 1615866
Status: VALIDATED
Authors:
References:
- Phys.Lett.B 777 (2018) 303-323
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
- gamma gamma -> mu+ mu- process.
The production of exclusive $\gamma\gamma\to\mu^+\mu^-$ events in proton-proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC, using data corresponding to an integrated luminosity of $3.2 \text{fb}^{-1}$. The measurement is performed for a dimuon invariant mass of between 12 GeV and 70 GeV, including the differential cross section as a function of the mass.
Source code:
ATLAS_2018_I1615866.cc
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76 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
namespace Rivet {
/// @brief gamma gamma -> mu+ mu-
class ATLAS_2018_I1615866 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2018_I1615866);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
ChargedFinalState cfs(Cuts::abseta < 2.5 and Cuts::pT>0.4);
declare(cfs,"CFS");
// Get muons which pass the initial kinematic cuts
IdentifiedFinalState muon_fs(Cuts::abseta < 2.4 && Cuts::pT > 6*GeV);
muon_fs.acceptIdPair(PID::MUON);
declare(muon_fs, "MUON_FS");
// histograms
book(_h_sigma,1,1,1);
book(_h_mass ,2,1,1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
if (cfs.size() != 2) vetoEvent; // no other charged particles in 2.5
// extract the muons
const Particles& muonFS = apply<IdentifiedFinalState>(event, "MUON_FS").particles();
// have 2 muons with opposite charge
if (muonFS.size() != 2) vetoEvent;
if (muonFS[0].pid() != -muonFS[1].pid()) vetoEvent;
// invariant mass between 12 and 70
double mmumu = (muonFS[0].momentum()+muonFS[1].momentum()).mass();
if(mmumu<12. or mmumu>70.) vetoEvent;
// cut pt >10 if pair mass >30
for(unsigned int ix=0;ix<2;++ix) {
if(mmumu>30 && muonFS[ix].perp()<10.) vetoEvent;
}
// fill histogram
_h_mass->fill(mmumu);
_h_sigma->fill(13000);
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_h_sigma, crossSection()/picobarn/sumOfWeights());
scale(_h_mass , crossSection()/picobarn/sumOfWeights());
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_sigma;
Histo1DPtr _h_mass;
/// @}
};
RIVET_DECLARE_PLUGIN(ATLAS_2018_I1615866);
}
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