rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

LHCB_2013_I1218996

Charm-hadron differential cross-sections in $p_\perp$ and rapidity
Experiment: LHCB (LHC 7TeV)
Inspire ID: 1218996
Status: VALIDATED
Authors:
  • Patrick Spradlin
References: Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
  • Minimum bias QCD events, proton--proton interactions at $\sqrt{s} = 7$ TeV.

Measurements of differential production cross-sections with respect to transverse momentum, $d \sigma(H_c + \mathrm{c.c.}) / d p_T$, for charm hadron species $H_c \in \{ D^0, D^+, D^\ast(2010)^+, D_s^+, \Lambda_c^+ \}$ in proton--proton collisions at center-of-mass energy $\sqrt{s}= 7$ TeV. The differential cross-sections are measured in bins of hadron transverse momentum ($p_T$) and rapidity ($y$) with respect to the beam axis in the region $0 < p_T < 8$ GeV/$c$ and $2.0 < y < 4.5$, where $p_T$ and $y$ are measured in the proton--proton CM frame. In this analysis code, it is assumed that the event coordinate system is in the proton--proton CM frame with the $z$-axis corresponding to the proton--proton collision axis (as usual). Contributions of charm hadrons from the decays of $b$-hadrons and other particles with comparably large mean lifetimes have been removed in the measurement. In this analysis code, this is implemented by counting only charm hadrons that do not have an ancestor that contains a $b$ quark.

Source code: LHCB_2013_I1218996.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// LHCb prompt charm hadron pT and rapidity spectra
 10  class LHCB_2013_I1218996 : public Analysis {
 11  public:
 12
 13    /// @name Constructors etc.
 14    /// @{
 15
 16    /// Constructor
 17    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2013_I1218996);
 18
 19    /// @}
 20
 21
 22    /// @name Analysis methods
 23    /// @{
 24
 25    /// Book histograms and initialise projections before the run
 26    void init() {
 27
 28      /// Initialise and register projections
 29      declare(UnstableParticles(), "UFS");
 30
 31      /// Book histograms
 32      book(_h_pdg421_Dzero_pT_y,     {2., 2.5, 3., 3.5, 4., 4.5});
 33      book(_h_pdg411_Dplus_pT_y,     {2., 2.5, 3., 3.5, 4., 4.5});
 34      book(_h_pdg413_Dstarplus_pT_y, {2., 2.5, 3., 3.5, 4., 4.5});
 35      book(_h_pdg431_Dsplus_pT_y,    {2., 2.5, 3., 3.5, 4., 4.5});
 36      for (size_t i = 1; i < _h_pdg421_Dzero_pT_y->numBins()+1; ++i) {
 37        size_t y = _h_pdg421_Dzero_pT_y->bin(i).index();
 38        book(_h_pdg421_Dzero_pT_y->bin(i),     2, 1, y);
 39        book(_h_pdg411_Dplus_pT_y->bin(i),     3, 1, y);
 40        book(_h_pdg413_Dstarplus_pT_y->bin(i), 4, 1, y);
 41        book(_h_pdg431_Dsplus_pT_y->bin(i),    5, 1, y);
 42      }
 43      book(_h_pdg4122_Lambdac_pT ,1, 1, 1);
 44    }
 45
 46
 47    /// Perform the per-event analysis
 48    void analyze(const Event& event) {
 49
 50      /// @todo Use PrimaryHadrons to avoid double counting and automatically remove the contributions from unstable?
 51      const UnstableParticles &ufs = apply<UnstableParticles> (event, "UFS");
 52      for (const Particle& p : ufs.particles() ) {
 53
 54        // We're only interested in charm hadrons
 55        if (!p.isHadron() || !p.hasCharm()) continue;
 56
 57        // Kinematic acceptance
 58        const double y = p.absrap(); ///< Double analysis efficiency with a "two-sided LHCb"
 59        const double pT = p.pT();
 60
 61        // Fiducial acceptance of the measurements
 62        if (pT > 8.0*GeV || y < 2.0 || y > 4.5) continue;
 63
 64        /// Experimental selection removes non-prompt charm hadrons: we ignore those from b decays
 65        if (p.fromBottom()) continue;
 66
 67        switch (p.abspid()) {
 68        case 411:
 69          _h_pdg411_Dplus_pT_y->fill(y, pT/GeV);
 70          break;
 71        case 421:
 72          _h_pdg421_Dzero_pT_y->fill(y, pT/GeV);
 73          break;
 74        case 431:
 75          _h_pdg431_Dsplus_pT_y->fill(y, pT/GeV);
 76          break;
 77        case 413:
 78          _h_pdg413_Dstarplus_pT_y->fill(y, pT/GeV);
 79          break;
 80        case 4122:
 81          _h_pdg4122_Lambdac_pT->fill(pT/GeV);
 82          break;
 83        }
 84      }
 85
 86    }
 87
 88
 89    /// Normalise histograms etc., after the run
 90    void finalize() {
 91      const double scale_factor = 0.5 * crossSection()/microbarn / sumOfWeights();
 92      scale(_h_pdg411_Dplus_pT_y, scale_factor);
 93      scale(_h_pdg421_Dzero_pT_y, scale_factor);
 94      scale(_h_pdg431_Dsplus_pT_y, scale_factor);
 95      scale(_h_pdg413_Dstarplus_pT_y, scale_factor);
 96      _h_pdg4122_Lambdac_pT->scaleW(scale_factor);
 97    }
 98
 99    /// @}
100
101
102  private:
103
104    /// @name Histograms
105    /// @{
106    Histo1DGroupPtr _h_pdg411_Dplus_pT_y;
107    Histo1DGroupPtr _h_pdg421_Dzero_pT_y;
108    Histo1DGroupPtr _h_pdg431_Dsplus_pT_y;
109    Histo1DGroupPtr _h_pdg413_Dstarplus_pT_y;
110    Histo1DPtr _h_pdg4122_Lambdac_pT;
111    /// @}
112
113
114  };
115
116
117  RIVET_DECLARE_PLUGIN(LHCB_2013_I1218996);
118
119}