Rivet analyses
Differential single diffractive cross sections at 8 TeV
Experiment: ATLAS, ALFA (LHC)
Inspire ID: 1762584
Status: VALIDATED
Authors: - Felix Kling
References: - Expt page: ATLAS-STDM-2018-01 - arXiv: 1911.00453 - JHEP 02 (2020) 042
Beams: p+ p+
Beam energies: (4000.0, 4000.0)GeV
Run details: - Single diffractive minimum bias events
A dedicated sample of Large Hadron Collider proton-proton collision data at centre-of-mass energy $\sqrt{s} = 8$ TeV is used to study inclusive single diffractive dissociation, pp → Xp. The intact final-state proton is reconstructed in the ATLAS ALFA forward spectrometer, while charged particles from the dissociated system X are measured in the central detector components. The fiducial range of the measurement is −4.0 < log10ξ < −1.6 and 0.016 < |t| < 0.43 GeV2, where ξ is the proton fractional energy loss and t is the squared four-momentum transfer. The total cross section integrated across the fiducial range is 1.59 ± 0.13 mb. Cross sections are also measured differentially as functions of ξ, t, and Δη, a variable that characterises the rapidity gap separating the proton and the system X. The data are consistent with an exponential t dependence, dσ/dt ≈ eBt with slope parameter B = 7.65 ± 0.34 GeV−2. Interpreted in the framework of triple Regge phenomenology, the ξ dependence leads to a pomeron intercept of α(0) = 1.07 ± 0.09.
Source
code:ATLAS_2019_I1762584.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FinalState.hh"
namespace Rivet {
/// @brief single-diffractive cross-sections at 8 TeV
class ATLAS_2019_I1762584 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2019_I1762584);
void init() {
// Inner Detector (ID) charged final states
// charged tracks with pT>200MeV, |eta|<2.5
Cut track_cuts = Cuts::abseta < 2.5 && Cuts::pT > 0.2*GeV;
const ChargedFinalState tracks(track_cuts);
declare(tracks, "tracks");
// Forward Detector (FD) protons
// protons with 0.016<|t|/GeV^2<0.43: 0.126<pT/GeV<0.655
Cut proton_t_cuts = Cuts::pT>0.126/GeV && Cuts::pT<0.655/GeV ;
// protons with -4<log10(Xi)<-1.6: 0.016<|t|/GeV^2<0.43: 3899.52<E<3999.6
Cut proton_xi_cuts = Cuts::E>3899.52/GeV && Cuts::E<3999.6/GeV ;
const ChargedFinalState protons(Cuts::pid==PID::PROTON && proton_t_cuts && proton_xi_cuts ) ;
declare(protons, "protons");
// Book histograms
book(_h_dSigma_dDeltaEta, 1, 1, 1);
book(_h_dSigma_dAbsT, 2, 1, 1);
book(_h_dSigma_dLog10Xi, 3, 1, 1);
}
void analyze(const Event& event) {
// Retrieve charged tracks in Inner Detector
const ChargedFinalState& tracks = apply<ChargedFinalState>(event, "tracks");
// Retrieve protons in ALFA detector
const ChargedFinalState protons = apply<ChargedFinalState>(event, "protons");
// Veto Events with more than one tagged proton
if (protons.size()!=1) vetoEvent;
const Particle tagProton = protons.particles()[0];
// Calculate |t|
const double AbsT = (tagProton.pT()/GeV)*(tagProton.pT()/GeV);
// Calculate Log10(Xi)
const double Log10Xi = log10(1.-(tagProton.E()/GeV)/4000.);
//Calculate DeltaEta
const double EtaEdge = 2.5*tagProton.pz()/abs(tagProton.pz());
double DeltaEta = 5;
for (const Particle& p : tracks.particles()) {
double DeltaEta_track = abs(p.eta() - EtaEdge);
if (DeltaEta_track<DeltaEta) DeltaEta=DeltaEta_track;
}
// Fill histograms
_h_dSigma_dDeltaEta->fill(DeltaEta);
_h_dSigma_dAbsT->fill(AbsT);
_h_dSigma_dLog10Xi->fill(Log10Xi);
}
/// Normalise histograms to units of millibarn
void finalize() {
// norm to generated cross-section in mb (after cuts)
scale(_h_dSigma_dAbsT, crossSection()/millibarn/sumOfWeights());
scale(_h_dSigma_dLog10Xi, crossSection()/millibarn/sumOfWeights());
scale(_h_dSigma_dDeltaEta, crossSection()/millibarn/sumOfWeights());
}
private:
Histo1DPtr _h_dSigma_dAbsT, _h_dSigma_dLog10Xi, _h_dSigma_dDeltaEta;
};
RIVET_DECLARE_PLUGIN(ATLAS_2019_I1762584);
}