rivet is hosted by Hepforge, IPPP Durham

## Rivet analyses reference

### ATLAS_2011_I894867

Measurement of the inelastic proton-proton cross-section at $\sqrt{s} =$7 TeV.
Experiment: ATLAS (LHC)
Inspire ID: 894867
Status: VALIDATED
Authors:
• Anton Karneyeu
• Sercan Sen
References:
Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
• Inelastic events (non-diffractive and inelastic diffractive).

Inelastic cross-section is measured for $\xi > 5 \times 10^{-6}$, where $\xi=M_X^2/s$ is calculated from the invariant mass, $M_X$, of hadrons selected using the largest rapidity gap in the event.

Source code: ATLAS_2011_I894867.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/FinalState.hh" namespace Rivet { class ATLAS_2011_I894867 : public Analysis { public: DEFAULT_RIVET_ANALYSIS_CTOR(ATLAS_2011_I894867); void init() { declare(FinalState(), "FS"); book(_h_sigma ,1, 1, 1); } void analyze(const Event& event) { const FinalState& fs = apply(event, "FS"); if (fs.size() < 2) vetoEvent; // need at least two particles to calculate gaps const Particles particles = fs.particles(cmpMomByEta); double etaprev = particles.front().eta(); double gapcenter = etaprev; double detamax = -1; for (const Particle& p : particles) { // sorted from minus to plus const double deta = p.eta() - etaprev; // guaranteed positive if (deta > detamax) { // largest gap so far detamax = deta; gapcenter = (p.eta() + etaprev)/2.; // find the center of the gap to separate the X and Y systems. } etaprev = p.eta(); } FourMomentum mxFourVector, myFourVector; for (const Particle& p : particles) (p.eta() > gapcenter ? mxFourVector : myFourVector) += p.momentum(); const double m2 = max(mxFourVector.mass2(), myFourVector.mass2()); const double xi = m2/sqr(sqrtS()); // sqrt(s) = 7000 GeV if (xi < 5e-6) vetoEvent; _h_sigma->fill(sqrtS()/GeV); } void finalize() { scale(_h_sigma, crossSection()/millibarn/sumOfWeights()); } Histo1DPtr _h_sigma; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(ATLAS_2011_I894867); }