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## Rivet analyses reference

### LHCB_2018_I1665223

Measurement of $pp$ inelastic cross-section at 13 TeV using prompt, long-lived particles in the LHCb fiducial phase-space
Experiment: LHCB (LHC)
Inspire ID: 1665223
Status: VALIDATED
Authors:
• Michael Schmelling
• Alex Grecu
References:
• JHEP 1806 (2018) 100
• DOI:10.1007/JHEP06(2018)100
• arXiv: 1803.10974
• LHCb-PAPER-2018-003, CERN-EP-2018-044
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
• Proton-proton interactions at 13 TeV centre-of-mass energy. LHCb minimum bias, inelastic events.

LHCb measurement of the inelastic interaction cross-section in proton-proton collisions at $\sqrt{s}=13$ TeV. Events are selected if they contain at least one prompt long-lived charged particle with momentum $p > 2$ GeV$/c$ and pseudorapidity ($\eta$) in the range $2 < \eta < 5$. A particle is long-lived if its proper (mean) lifetime is larger than $0.3 \times 10^{-10}$ s, (proper $c\tau > 9$ mm) and it is prompt if it is produced directly in the $pp$ collision or if none of its ancestors is long-lived. This definition is recommended by the LHC Minimum Bias and Underlying Event working group. Prompt long-lived charged hadrons should be used themselves in vetoeing events rather than their charged decay products (e.g. Sigma +/-, Xi and Omega decays are blocked).

Source code: LHCB_2018_I1665223.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/ChargedFinalState.hh" namespace Rivet { /// @brief Inelastic xsection in pp collisions at 13 TeV for charged particles in LHCb acceptance class LHCB_2018_I1665223 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(LHCB_2018_I1665223); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { // Register projection declare(ChargedFinalState(Cuts::etaIn(ETAMIN, ETAMAX)), "lbCFS"); // Book histogram book(_h_ppInel, 1, 1, 1); } /// Perform the per-event analysis void analyze(const Event& event) { // Eliminate non-inelastic events and empty events in LHCb const ChargedFinalState& cfs = apply(event, "lbCFS"); if (cfs.particles().size() == 0) vetoEvent; for (const Particle& myp : cfs.particles()) { if (hasLongLivedParent(myp)) continue; if (!isLongLivedParticle(myp)) continue; // Only particles with p > 2 GeV measured if (myp.momentum().p() < PMIN) continue; // Histo gets filled only for inelastic events (at least one prompt charged particle) _h_ppInel->fill(sqrtS()); break; } } /// Normalise histograms etc., after the run void finalize() { scale(_h_ppInel, crossSection()/millibarn/sumOfWeights()); // norm to cross section (one-sided LHCb) } //@} bool isLongLivedParticle(const Particle& p) { // Stable long-lived final-state charged particles in LHCb static const int stablePids[9] = {11,13,211,321,2212,3112,3222,3312,3334}; for (int stablePid : stablePids) { if (p.abspid() == stablePid) return true; } return false; } bool hasLongLivedParent(const Particle& p) { // List of PDG IDs for particle with lifetimes higher than 0.03 ns (3.E-11 s) - long lived particles according to LHC MB&UE WG static const int longLivedPids[20] = {3334,3322,3312,3222,3122,3112,2212,2112,321,310,130,211,20022,480000000,11,12,13,14,16,22}; for (int longLivedPid : longLivedPids) { if (p.hasParentWith(Cuts::abspid == longLivedPid)) return true; } return false; } /// @name Histogram Histo1DPtr _h_ppInel; /// Cut constants const double ETAMIN = 2.0, ETAMAX = 5.0, PMIN = 2.0*GeV; }; DECLARE_RIVET_PLUGIN(LHCB_2018_I1665223); }