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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
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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<FinalState>(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);
}
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