Rivet analyses

Λb0/Λ̄b0 Asymmetry at 7 and 8 TeV

Experiment: LHCB (LHC)

Inspire ID: 1888216

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - JHEP 10 (2021) 060

Beams: p+ p+

Beam energies: (3500.0, 3500.0); (4000.0, 4000.0)GeV

Run details: - Lambda_b production

Measurement of the production asymmetry for Λb0/Λ̄b0 at 7 and 8 TeV by LHCb.

Source code:LHCB_2021_I1888216.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Lambda_b asymmetry
  class LHCB_2021_I1888216 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2021_I1888216);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {
      // projection
      declare(UnstableParticles(), "UFS");
      //histograms
      for (double eVal : allowedEnergies()) {
        const int en(eVal + 0.5);
        if (isCompatibleWithSqrtS(eVal)) _sqs = en;
        size_t ih(en == 8000);
        book(_e[en], 1, 1, ih + 1);
        book(_e[en + 1], 2, 1, ih + 1);
        for (size_t ix = 0; ix < 2; ++ix) {
          book(_h_y[en + ix], "TMP/h_y_ " + toString(en + ix + 1), refData(1, 1, 1));
          book(_h_pT[en + ix], "TMP/h_pT_" + toString(en + ix + 1), refData(2, 1, 1));
        }
      }
      raiseBeamErrorIf(_sqs == 0);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::abspid == 5122)) {
        const double pT = p.perp() / GeV;
        const double y = p.absrap();
        if (y < 2.15 || y > 4.1) continue;
        if (pT < 2 || pT > 27) continue;
        bool anti = p.pid() < 0;
        _h_pT[_sqs + anti]->fill(pT);
        _h_y[_sqs + anti]->fill(y);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // calculate asymmetry in %
      for (double eVal : allowedEnergies()) {
        const int en(eVal + 0.5);
        asymm(_h_y[en + 0], _h_y[en + 1], _e[en]);
        asymm(_h_pT[en + 0], _h_pT[en + 1], _e[en + 1]);
      }
      scale(_e, 100.);
    }

    /// @}


    /// @name Histograms
    /// @{
    map<int, Histo1DPtr> _h_pT, _h_y;
    map<int, Estimate1DPtr> _e;
    int _sqs = 0;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(LHCB_2021_I1888216);

}