Rivet analyses

title: LHCB_2017_I1596893

Mass distributions in $B^0\to p\bar\Lambda\pi^-$ and $B^0_s\to p\bar\Lambda K^-$

Experiment: LHCB (LHC)

Inspire ID: 1596893

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 119 (2017) 4, 041802

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0 and B_s0 mesons, original pp

Mass distributions in $B^0\to p\bar\Lambda\pi^-$ and $B^0_s\to p\bar\Lambda K^-$. Data read from plots in paper but background subtracted and corrected for efficiency.

Source code:LHCB_2017_I1596893.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B0 -> p Lambdabar0 pi- and Bs0 -> p Lambdabar0 K- class LHCB_2017_I1596893 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2017_I1596893);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 or Cuts::abspid == 531);
  declare(ufs, "UFS");
  DecayedParticles B0(ufs);
  B0.addStable(3122);
  B0.addStable(-3122);
  declare(B0, "B0");
  // book histograms
  for (unsigned int ix = 0; ix < 2; ++ix)
    for (unsigned int iy = 0; iy < 3; ++iy) book(_h[ix][iy], 1 + ix, 1, 1 + iy);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode1 = {{2212, 1}, {-3122, 1}, {-211, 1}};
  static const map<PdgId, unsigned int>& mode1CC = {{-2212, 1}, {3122, 1}, {211, 1}};
  static const map<PdgId, unsigned int>& mode2 = {{2212, 1}, {-3122, 1}, {-321, 1}};
  static const map<PdgId, unsigned int>& mode2CC = {{-2212, 1}, {3122, 1}, {321, 1}};
  DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
  // loop over particles
  for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
    int sign = 1, imode = 0;
    if (B0.decaying()[ix].abspid() == 511) {
      if (B0.decaying()[ix].pid() > 0 && B0.modeMatches(ix, 3, mode1)) {
        sign = 1;
      }
      else if (B0.decaying()[ix].pid() < 0 && B0.modeMatches(ix, 3, mode1CC)) {
        sign = -1;
      }
      else
        continue;
      imode = 0;
    }
    else {
      if (B0.decaying()[ix].pid() > 0 && B0.modeMatches(ix, 3, mode2)) {
        sign = 1;
      }
      else if (B0.decaying()[ix].pid() < 0 && B0.modeMatches(ix, 3, mode2CC)) {
        sign = -1;
      }
      else
        continue;
      imode = 1;
    }
    const Particle& pp = B0.decayProducts()[ix].at(sign * 2212)[0];
    const Particle& LamBar = B0.decayProducts()[ix].at(-sign * 3122)[0];
    const Particle& pim = B0.decayProducts()[ix].at(-sign * (imode == 0 ? 211 : 321))[0];
    _h[imode][0]->fill((pp.momentum() + LamBar.momentum()).mass());
    _h[imode][1]->fill((pp.momentum() + pim.momentum()).mass());
    _h[imode][2]->fill((pim.momentum() + LamBar.momentum()).mass());
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 2; ++ix)
    for (unsigned int iy = 0; iy < 3; ++iy) normalize(_h[ix][iy], 1., false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2][3];
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2017_I1596893);

} ```