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## Rivet analyses reference

### ATLAS_2019_I1762584

Differential single diffractive cross sections at 8 TeV
Experiment: ATLAS, ALFA (LHC)
Inspire ID: 1762584
Status: VALIDATED
Authors:
• Felix Kling
References:
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, $pp \to X p$. 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 $-4.0 < \log_{10} \xi < -1.6$ and $0.016 < |t| < 0.43$ GeV$^{2}$, where $\xi$ is the proton fractional energy loss and $t$ is the squared four-momentum transfer. The total cross section integrated across the fiducial range is $1.59 \pm 0.13$ mb. Cross sections are also measured differentially as functions of $\xi$, $t$, and $\Delta \eta$, a variable that characterises the rapidity gap separating the proton and the system X. The data are consistent with an exponential $t$ dependence, d$\sigma$/d$t \approx e^{Bt}$ with slope parameter $B = 7.65 \pm 0.34$ GeV$^{-2}$. Interpreted in the framework of triple Regge phenomenology, the $\xi$ dependence leads to a pomeron intercept of $\alpha(0) = 1.07 \pm 0.09$.

Source code: ATLAS_2019_I1762584.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 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 // -*- 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 DEFAULT_RIVET_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: 0.1260.126/GeV && Cuts::pT<0.655/GeV ; // protons with -43899.52/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(event, "tracks"); // Retrieve protons in ALFA detector const ChargedFinalState protons = apply(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_trackfill(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; }; DECLARE_RIVET_PLUGIN(ATLAS_2019_I1762584); }