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CMS_2010_S8547297

Charged particle transverse momentum and pseudorapidity spectra from proton-proton collisions at 900 and 2360 GeV.
Experiment: CMS (LHC)
Inspire ID: 845323
Status: VALIDATED
Authors:
  • A. Knutsson
References: Beams: p+ p+
Beam energies: (450.0, 450.0); (1180.0, 1180.0) GeV
Run details:
  • Non-single-diffractive (NSD) events only. Should include double-diffractive (DD) events and non-diffractive (ND) events but NOT single-diffractive (SD) events. Examples, in Pythia6 the SD processes to be turned off are 92 and 93, and in Pythia8 the SD processes are 103 and 104 (also called SoftQCD:singleDiffractive).

Charged particle spectra are measured in proton-proton collisions at center-of-mass energies 900 and 2360 GeV. The spectra are normalized to all non-single-diffractive (NSD) events using corrections for trigger and selection efficiency, acceptance, and branching ratios. There are transverse-momentum (pT) spectra from 0.1 to 2 GeV in bins of pseudorapidity (eta) and pT spectra from 0.1 to 4 GeV for |eta|<2.4. The eta spectra come from the average of three methods and cover |eta|<2.5 and are corrected to include all pT. The data were corrected according to the SD/DD/ND content of the CMS trigger, as predicted by PYTHIA6. The uncertainties connected with correct or incorrect modelling of diffraction were included in the systematic errors.

Source code: CMS_2010_S8547297.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {


  class CMS_2010_S8547297 : public Analysis {
  public:

    CMS_2010_S8547297() : Analysis("CMS_2010_S8547297") {}


    void init() {
      ChargedFinalState cfs(-2.5, 2.5, 0.0*GeV);
      declare(cfs, "CFS");

      if (fuzzyEquals(sqrtS()/GeV, 900)) {
        for (int d=1; d<=3; d++) {
          for (int y=1; y<=4; y++) {
            _h_dNch_dpT.push_back(bookHisto1D(d, 1, y));
          }
        }
        _h_dNch_dpT_all = bookHisto1D(7, 1, 1);
        _h_dNch_dEta = bookHisto1D(8, 1, 1);
      } else if (fuzzyEquals(sqrtS()/GeV, 2360)) {
        for (int d=4; d<=6; d++) {
          for (int y=1; y<=4; y++) {
            _h_dNch_dpT.push_back(bookHisto1D(d, 1, y));
          }
        }
        _h_dNch_dpT_all = bookHisto1D(7, 1, 2);
        _h_dNch_dEta = bookHisto1D(8, 1, 2);
      }
    }


    void analyze(const Event& event) {
      const double weight = event.weight();

      //charged particles
      const ChargedFinalState& charged = apply<ChargedFinalState>(event, "CFS");

      foreach (const Particle& p, charged.particles()) {
        //selecting only charged hadrons
        if (! PID::isHadron(p.pid())) continue;

        const double pT = p.pT();
        const double eta = p.eta();

        // The data is actually a duplicated folded distribution.  This should mimic it.
        _h_dNch_dEta->fill(eta, 0.5*weight);
        _h_dNch_dEta->fill(-eta, 0.5*weight);
        if (fabs(eta) < 2.4 && pT > 0.1*GeV) {
          if (pT < 4.0*GeV) {
            _h_dNch_dpT_all->fill(pT/GeV, weight/(pT/GeV));
            if (pT < 2.0*GeV) {
              int ietabin = int(fabs(eta)/0.2);
              _h_dNch_dpT[ietabin]->fill(pT/GeV, weight);
            }
          }
        }
      }
    }


    void finalize() {
      const double normfac = 1.0/sumOfWeights(); // Normalizing to unit eta is automatic
      // The pT distributions in bins of eta must be normalized to unit eta.  This is a factor of 2
      // for the |eta| times 0.2 (eta range).
      // The pT distributions over all eta are normalized to unit eta (2.0*2.4) and by 1/2*pi*pT.
      // The 1/pT part is taken care of in the filling.  The 1/2pi is taken care of here.
      const double normpT = normfac/(2.0*0.2);
      const double normpTall = normfac/(2.0*M_PI*2.0*2.4);

      for (size_t ietabin=0; ietabin < _h_dNch_dpT.size(); ietabin++){
        scale(_h_dNch_dpT[ietabin], normpT);
      }
      scale(_h_dNch_dpT_all, normpTall);
      scale(_h_dNch_dEta, normfac);
    }


  private:

    std::vector<Histo1DPtr> _h_dNch_dpT;
    Histo1DPtr _h_dNch_dpT_all;
    Histo1DPtr _h_dNch_dEta;

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(CMS_2010_S8547297);

}