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LHCB_2015_I1396331

Charm hadron differential cross-sections in $p_T$ and rapidity at $\sqrt{s} = 13$ TeV
Experiment: LHCB (LHC 13TeV)
Inspire ID: 1396331
Status: VALIDATED
Authors:
  • Dominik Muller
  • Patrick Spradlin
References:
  • JHEP 1603 (2016) 159 JHEP 1609 (2016) 013 JHEP 1705 (2017) 074
  • doi 10.1007/JHEP09(2016)013 10.1007/JHEP05(2017)074 10.1007/JHEP03(2016)159
  • arXiv 1510.01707 [hep-ex]
  • LHCB-PAPER-2015-041, CERN-PH-EP-2015-272
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
  • Minimum bias QCD events, proton--proton interactions at $\sqrt{s} = 13$ 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 $H_c \in \{ D^0, D^+, D^\ast(2010)^+, D_s^+ \}$ in proton--proton collisions at center-of-mass energy $\sqrt{s}= 13$ 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 $0 < p_T < 15$ 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_2015_I1396331.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh"
  4
  5namespace Rivet {
  6
  7  /// LHCb prompt charm hadron pT and rapidity spectra
  8  class LHCB_2015_I1396331 : public Analysis {
  9  public:
 10
 11    /// Constructor
 12    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2015_I1396331);
 13
 14
 15    /// @name Analysis methods
 16    /// @{
 17
 18    /// Book histograms and initialise projections before the run
 19    void init() {
 20
 21      /// Initialise and register projections
 22      Cut selection = (Cuts::abspid == 411 || Cuts::abspid == 421 || Cuts::abspid == 431 || Cuts::abspid == 413) \
 23                       && Cuts::pT < 15.0 && Cuts::absrapIn(2.0, 4.5);
 24      declare(UnstableParticles(selection), "UPDs");
 25
 26      /// Book histograms
 27      book(_h_pdg421_Dzero_pT_y, {2., 2.5, 3., 3.5, 4., 4.5});
 28      for (auto& b : _h_pdg421_Dzero_pT_y->bins()) {
 29        book(b, 1, 1, b.index());
 30      }
 31
 32      book(_h_pdg411_Dplus_pT_y, {2., 2.5, 3., 3.5, 4., 4.5});
 33      for (auto& b : _h_pdg411_Dplus_pT_y->bins()) {
 34        book(b, 2, 1, b.index());
 35      }
 36
 37      book(_h_pdg431_Dsplus_pT_y, {2., 2.5, 3., 3.5, 4., 4.5});
 38      for (auto& b : _h_pdg431_Dsplus_pT_y->bins()) {
 39        book(b, 3, 1, b.index());
 40      }
 41
 42      book(_h_pdg413_Dstarplus_pT_y, {2., 2.5, 3., 3.5, 4., 4.5});
 43      for (auto& b : _h_pdg413_Dstarplus_pT_y->bins()) {
 44        book(b, 4, 1, b.index());
 45      }
 46
 47      // Temporary histos for ratios
 48      book(_hbr_Dzero, {2., 2.5, 3., 3.5, 4., 4.5});
 49      book(_hbr_Dplus, {2., 2.5, 3., 3.5, 4., 4.5});
 50      book(_hbr_Ds,    {2., 2.5, 3., 3.5, 4., 4.5});
 51      book(_hbr_Dstar, {2., 2.5, 3., 3.5, 4., 4.5});
 52      for (size_t i=1; i<_hbr_Ds->numBins()+1; ++i) {
 53      	book(_hbr_Dzero->bin(i), "/TMP/Dzero"+to_str(i), refData(9, 1, 2));
 54      	book(_hbr_Dplus->bin(i), "/TMP/Dplus"+to_str(i), refData(9, 1, 2));
 55      	book(_hbr_Ds->bin(i),    "/TMP/Ds"+to_str(i),    refData(9, 1, 2));
 56      	book(_hbr_Dstar->bin(i), "/TMP/Dstar"+to_str(i), refData(9, 1, 2));
 57      }
 58
 59    }
 60
 61
 62    /// Perform the per-event analysis
 63    void analyze(const Event& event) {
 64
 65      /// @todo Use PrimaryHadrons to avoid double counting and automatically remove the contributions from unstable?
 66      const UnstableParticles &ufs = apply<UnstableParticles> (event, "UPDs");
 67      for (const Particle& p : ufs.particles()) {
 68
 69        if (p.fromBottom()) continue;
 70
 71        const PdgId apid = p.abspid();
 72        const double y = p.absrap(); ///< Double analysis efficiency with a "two-sided LHCb"
 73        const double pT = p.pT()/GeV;
 74
 75        // select inclusive decay modes
 76        Particles daus;
 77        switch (apid) {
 78        case 411:
 79          _h_pdg411_Dplus_pT_y->fill(y, pT);
 80          // veto on decay channel [D+ -> K- pi+ pi+]cc
 81          if (p.children().size() != 3) break;
 82          if ( ((p.children(Cuts::pid == -321).size() == 1) && (p.children(Cuts::pid == 211).size() == 2)) ||
 83          		 ((p.children(Cuts::pid == 321).size() == 1) && (p.children(Cuts::pid == -211).size() == 2)) )
 84          	_hbr_Dplus->fill(y, pT); // MSG_INFO("Found [ D+ -> K- pi+ pi+ ]cc..."); };
 85          break;
 86        case 421:
 87          _h_pdg421_Dzero_pT_y->fill(y, pT);
 88          // veto on decay channel [D0 -> K- pi+]cc
 89          if (p.children().size() != 2) break;
 90          if ( ((p.children(Cuts::pid == -321).size() == 1) && (p.children(Cuts::pid == 211).size() == 1)) ||
 91          		 ((p.children(Cuts::pid == 321).size() == 1) && (p.children(Cuts::pid == -211).size() == 1)) )
 92          	_hbr_Dzero->fill(y, pT); // MSG_INFO("Found [ D0 -> K- pi+ ]cc..."); };
 93
 94          break;
 95        case 431:
 96          _h_pdg431_Dsplus_pT_y->fill(y, pT);
 97          //veto on decay channel [Ds+ -> [K+ K-]phi0 pi+]cc
 98          if (p.children().size() != 2) break;
 99          daus = p.children(Cuts::pid == 333);
100          if ( (daus.size() == 1) && (p.children(Cuts::abspid == 211).size() == 1) &&
101          		 (daus.front().children(Cuts::abspid ==321).size() == 2) )
102          	_hbr_Ds->fill(y, pT); // MSG_INFO("Found [ Ds+ -> phi0(-> K+ K-) pi+ ]cc..."); };
103          break;
104        case 413:
105          _h_pdg413_Dstarplus_pT_y->fill(y, pT);
106          // veto on decay channel [D*+ -> [K- pi+]D0 pi+]cc
107          if (p.children().size() != 2) break;
108          daus = p.children(Cuts::pid == 421);
109          if ( (daus.size() == 1) && (p.children(Cuts::abspid == 211).size() == 1) &&
110          		( daus.front().children().size() == 2 ) &&
111          		( ( (daus.front().children(Cuts::pid == -321).size() == 1 ) && (daus.front().children(Cuts::pid == 211).size() == 1 )	) ||
112          		  ( (daus.front().children(Cuts::pid == 321).size() == 1 ) && (daus.front().children(Cuts::pid == -211).size() == 1 ) ) ) )
113          	_hbr_Dstar->fill(y, pT); // MSG_INFO("Found [ D*+ -> D0 (-> K- pi+)cc pi+ ]cc..."); };
114          break;
115        default:
116        	break;
117        }
118      }
119
120    }
121
122
123    /// Normalise histograms etc., after the run
124    void finalize() {
125      Histo1DPtr h;
126      Histo1DPtr hden;
127      /// Factor of 0.5 to correct for the abs(rapidity) used above
128      const double scale_factor = 0.5 * crossSection()/microbarn / sumOfWeights();
129      scale(_h_pdg411_Dplus_pT_y,     scale_factor);
130      scale(_h_pdg431_Dsplus_pT_y,    scale_factor);
131      scale(_h_pdg413_Dstarplus_pT_y, scale_factor);
132      scale(_h_pdg421_Dzero_pT_y,     scale_factor);
133
134
135      // Do ratios
136      for (size_t i = 0; i < 5; ++i) {
137      	// book final ratio plots
138        book(hr_DplusDzero[i], 9, 1, i+1);
139        book(hr_DsDzero[i], 10, 1, i+1);
140        book(hr_DstarDzero[i], 11, 1, i+1);
141        book(hr_DsDplus[i], 12, 1, i+1);
142        book(hr_DstarDplus[i], 13, 1, i+1);
143        book(hr_DsDstar[i], 14, 1, i+1);
144        // fill ratio plots
145      	divide(_hbr_Dplus->bin(i+1), _hbr_Dzero->bin(i+1), hr_DplusDzero[i]);
146      	divide(_hbr_Ds->bin(i+1),    _hbr_Dzero->bin(i+1), hr_DsDzero[i]);
147      	divide(_hbr_Dstar->bin(i+1), _hbr_Dzero->bin(i+1), hr_DstarDzero[i]);
148      	divide(_hbr_Ds->bin(i+1),    _hbr_Dplus->bin(i+1), hr_DsDplus[i]);
149      	divide(_hbr_Dstar->bin(i+1), _hbr_Dplus->bin(i+1), hr_DstarDplus[i]);
150      	divide(_hbr_Ds->bin(i+1),    _hbr_Dstar->bin(i+1), hr_DsDstar[i]);
151      	// scale 100x as measurement is in %
152      	hr_DplusDzero[i]->scale(100.);
153      	hr_DsDzero[i]->scale(100.);
154      	hr_DstarDzero[i]->scale(100.);
155      	hr_DsDplus[i]->scale(100.);
156      	hr_DstarDplus[i]->scale(100.);
157      	hr_DsDstar[i]->scale(100.);
158      }
159    }
160
161    /// @}
162
163
164  private:
165
166    /// @name Histograms
167    /// @{
168    Histo1DGroupPtr _h_pdg411_Dplus_pT_y,     _hbr_Dplus;
169    Histo1DGroupPtr _h_pdg421_Dzero_pT_y,     _hbr_Dzero;
170    Histo1DGroupPtr _h_pdg431_Dsplus_pT_y,    _hbr_Ds;
171    Histo1DGroupPtr _h_pdg413_Dstarplus_pT_y, _hbr_Dstar;
172    Estimate1DPtr hr_DplusDzero[5];
173    Estimate1DPtr hr_DsDzero[5];
174    Estimate1DPtr hr_DstarDzero[5];
175    Estimate1DPtr hr_DsDplus[5];
176    Estimate1DPtr hr_DstarDplus[5];
177    Estimate1DPtr hr_DsDstar[5];
178    /// @}
179
180  };
181
182
183  RIVET_DECLARE_PLUGIN(LHCB_2015_I1396331);
184
185}