Rivet analyses

title: LHCB_2021_I1888216

$\Lambda_b^0/\bar{\Lambda}_b^0$ Asymmetry at 7 and 8 TeV

Experiment: LHCB (LHC)

Inspire ID: 1888216

Status: VALIDATED

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 $\Lambda_b^0/\bar{\Lambda}_b^0$ at 7 and 8 TeV by LHCb.

Source code:LHCB_2021_I1888216.cc

```c++ // -- 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);

} ```