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CMS_2017_I1608166

Measurement of charged pion, kaon, and proton production in proton-proton collisions at 13 TeV
Experiment: CMS (LHC)
Inspire ID: 1608166
Status: VALIDATED REENTRANT
Authors:
  • Markus Seidel
References:
  • Phys. Rev. D 96, 112003 (201
  • DOI:10.1103/PhysRevD.96.112003
  • arXiv: 1706.10194
  • CMS-FSQ-16-004
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
  • Minimum Bias inelastic collisions

Transverse momentum spectra of charged pions, kaons, and protons are measured in proton-proton collisions at sqrt(s)=13 TeV with the CMS detector at the LHC. The particles, identified via their energy loss in the silicon tracker, are measured in the transverse momentum range of pT = 0.1-1.7 GeV/c and rapidities |y|<1. The pT spectra and integrated yields are compared to previous results at smaller sqrt(s) and to predictions of Monte Carlo event generators. The average pT increases with particle mass and charged particle multiplicity of the event. Comparisons with previous CMS results at s=0.9, 2.76, and 7 TeV show that the average pT and the ratios of hadron yields feature very similar dependences on the particle multiplicity in the event, independently of the center-of-mass energy of the pp collision.

Source code: CMS_2017_I1608166.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Tools/ParticleName.hh"

namespace Rivet {


  /// Measurement of charged pion, kaon, and proton production in 13 TeV pp collisions
  class CMS_2017_I1608166 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(CMS_2017_I1608166);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {
      const ChargedFinalState cfs(Cuts::absrap < 1.);
      declare(cfs, "CFS");
      //
      // pt spectra
      book(_h[PID::PIPLUS],  "d01-x01-y01");
      book(_h[PID::KPLUS],   "d01-x01-y02");
      book(_h[PID::PROTON],  "d01-x01-y03");
      book(_h[PID::PIMINUS], "d02-x01-y01");
      book(_h[PID::KMINUS],  "d02-x01-y02");
      book(_h[PID::PBAR],    "d02-x01-y03");

      // negative/positive ratios
      /// @todo Reinstate when ratios in HepData
      // book(_s["pi-/pi+"], "d100-x01-y01");
      // book(_s["k-/k+"],   "d100-x01-y02");
      // book(_s["p~/p"],    "d100-x01-y03");

      // k/pi and p/pi ratios
      /// @todo Reinstate when ratios in HepData
      // book(_hkpi[PID::PIPLUS], "TMP/hkpi/pi", refData(101, 1, 1));
      // book(_hkpi[PID::KPLUS],  "TMP/hkpi/k",  refData(101, 1, 1));
      // book(_hppi[PID::PIPLUS], "TMP/hppi/pi", refData(101, 1, 2));
      // book(_hppi[PID::PROTON], "TMP/hppi/p",  refData(101, 1, 2));
      // book(_s["k/pi"],    "d101-x01-y01");
      // book(_s["p/pi"],    "d101-x01-y02");
    }


    void analyze(const Event& event) {

      const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
      for (const Particle& p : cfs.particles()) {

        // protections against MC generators decaying long-lived particles
        if (p.hasAncestor(310)  || p.hasAncestor(-310)  ||  // K0s
            p.hasAncestor(130)  || p.hasAncestor(-130)  ||  // K0l
            p.hasAncestor(3322) || p.hasAncestor(-3322) ||  // Xi0
            p.hasAncestor(3122) || p.hasAncestor(-3122) ||  // Lambda
            p.hasAncestor(3222) || p.hasAncestor(-3222) ||  // Sigma+/-
            p.hasAncestor(3312) || p.hasAncestor(-3312) ||  // Xi-/+
            p.hasAncestor(3334) || p.hasAncestor(-3334))    // Omega-/+
          continue;

        if (theParticles.find(p.pid()) != theParticles.end()) {
          // fill pt spectra
          _h[p.pid()]->fill(p.pt() / GeV);
          // fill tmp histos for ratios
          //if (p.abspid() != PID::PROTON)
          //  _hkpi[p.abspid()]->fill(p.pt() / GeV);
          //if (p.abspid() != PID::KPLUS)
          //  _hppi[p.abspid()]->fill(p.pt() / GeV);
        }

      }

    }


    void finalize() {

      /// @todo Reinstate when ratios in HepData
      // divide(_h[PID::PIMINUS], _h[PID::PIPLUS], _s["pi-/pi+"]);
      // divide(_h[PID::KMINUS],  _h[PID::KPLUS],  _s["k-/k+"]);
      // divide(_h[PID::PBAR],    _h[PID::PROTON], _s["p~/p"]);

      /// @todo Reinstate when ratios in HepData
      // divide(_hkpi[PID::KPLUS],  _hkpi[PID::PIPLUS], _s["k/pi"]);
      // divide(_hppi[PID::PROTON], _hppi[PID::PIPLUS], _s["p/pi"]);

      scale(_h, 1./2./sumOfWeights());

    }


    set<int> theParticles = {PID::PIPLUS, PID::KPLUS, PID::PROTON, PID::PIMINUS, PID::KMINUS, PID::PBAR};

    map<int, Histo1DPtr> _h;
    map<int, Histo1DPtr> _hkpi, _hppi;
    /// @todo Reinstate when ratios in HepData
    // map<string, Scatter2DPtr> _s;

  };


  DECLARE_RIVET_PLUGIN(CMS_2017_I1608166);

}