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BESIII_2024_I2819140

Exclusive $D^0\to K^-\ell^+\nu_\ell$ and $D^+\to \bar{K}^0\ell^+\nu_\ell$ decays
Experiment: BESIII (BEPC)
Inspire ID: 2819140
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References: Beams: * *
Beam energies: ANY
Run details:
  • Events with D-decays, either particle guns or collisions.

Differential decay rates for semi-leptonic $D^0\to K^-\ell^+\nu_\ell$ and $D^+\to \bar{K}^0\ell^+\nu_\ell$ decays

Source code: BESIII_2024_I2819140.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief D0 -> K- ell+ nu_ell and D+ -> Kbar0 ell+ nu_ell
  9  class BESIII_2024_I2819140 : public Analysis {
 10  public:
 11
 12    /// Constructor
 13    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2819140);
 14
 15
 16    /// @name Analysis methods
 17    /// @{
 18
 19    /// Book histograms and initialise projections before the run
 20    void init() {
 21
 22      // Initialise and register projections
 23      declare(UnstableParticles(Cuts::abspid==411 || Cuts::abspid==421 ), "UFS");
 24
 25      for(unsigned int ix=0;ix<4;++ix) {
 26        book(_h[ix], 1+ix , 1 ,1);
 27        if(ix>1) continue;
 28        book(_c[ix], "TMP/c_"+toString(ix+1));
 29      }
 30    }
 31
 32    // Calculate the Q2 using mother and daugher meson
 33    double q2(const Particle& B, int mesonID) {
 34      FourMomentum q = B.mom() - select(B.children(), Cuts::pid==mesonID)[0];
 35      return q*q;
 36    }
 37
 38    // Check for explicit decay into pdgids
 39    bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
 40      // Trivial check to ignore any other decays but the one in question modulo photons
 41      const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
 42      if (children.size()!=ids.size()) return false;
 43      // Check for the explicit decay
 44      return all(ids, [&](int i){return count(children, hasPID(i))==1;});
 45    }
 46
 47    /// Perform the per-event analysis
 48    void analyze(const Event& event) {
 49
 50      // Loop over D mesons
 51      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
 52        if(p.pid()==421) {
 53          _c[0]->fill();
 54          if(isSemileptonicDecay(p, {PID::KMINUS, PID::EPLUS, PID::NU_E})) {
 55            _h[0]->fill(q2(p, PID::KMINUS));
 56          }
 57          else if(isSemileptonicDecay(p, {PID::KMINUS, PID::ANTIMUON, PID::NU_MU})) {
 58            _h[1]->fill(q2(p, PID::KMINUS));
 59          }
 60        }
 61        else if(p.pid()==-421) {
 62          _c[0]->fill();
 63          if(isSemileptonicDecay(p, {PID::KPLUS, PID::EMINUS, PID::NU_EBAR})) {
 64            _h[0]->fill(q2(p, PID::KPLUS));
 65          }
 66          else if(isSemileptonicDecay(p, {PID::KPLUS, PID::MUON, PID::NU_MUBAR})) {
 67            _h[1]->fill(q2(p, PID::KPLUS));
 68          }
 69        }
 70        else if(p.pid()==411) {
 71          _c[1]->fill();
 72          if(isSemileptonicDecay(p, {-311, PID::EPLUS, PID::NU_E})) {
 73            _h[2]->fill(q2(p, -311));
 74          }
 75          else if(isSemileptonicDecay(p, {-311, PID::ANTIMUON, PID::NU_MU})) {
 76            _h[3]->fill(q2(p, -311));
 77          }
 78          else if(isSemileptonicDecay(p, { 130, PID::EPLUS, PID::NU_E})) {
 79            _h[2]->fill(q2(p, 130));
 80          }
 81          else if(isSemileptonicDecay(p, { 130, PID::ANTIMUON, PID::NU_MU})) {
 82            _h[3]->fill(q2(p, 130));
 83          }
 84          else if(isSemileptonicDecay(p, { 310, PID::EPLUS, PID::NU_E})) {
 85            _h[2]->fill(q2(p, 310));
 86          }
 87          else if(isSemileptonicDecay(p, { 310, PID::ANTIMUON, PID::NU_MU})) {
 88            _h[3]->fill(q2(p, 310));
 89          }
 90        }
 91        else if(p.pid()==-411) {
 92          _c[1]->fill();
 93          if(isSemileptonicDecay(p, {311, PID::EMINUS, PID::NU_EBAR})) {
 94            _h[2]->fill(q2(p, 311));
 95          }
 96          else if(isSemileptonicDecay(p, {311, PID::MUON, PID::NU_MUBAR})) {
 97            _h[3]->fill(q2(p, 311));
 98          }
 99          else if(isSemileptonicDecay(p, { 130, PID::EMINUS, PID::NU_EBAR})) {
100            _h[2]->fill(q2(p, 130));
101          }
102          else if(isSemileptonicDecay(p, { 130, PID::MUON, PID::NU_MUBAR})) {
103            _h[3]->fill(q2(p, 130));
104          }
105          else if(isSemileptonicDecay(p, { 310, PID::EMINUS, PID::NU_EBAR})) {
106            _h[2]->fill(q2(p, 310));
107          }
108          else if(isSemileptonicDecay(p, { 310, PID::MUON, PID::NU_MUBAR})) {
109            _h[3]->fill(q2(p, 310));
110          }
111        }
112      }
113    }
114
115
116    /// Normalise histograms etc., after the run
117    void finalize() {
118      // lifetimes from PDG 2022 [ns] (as in paper)
119      double tau[2] = {410.3e-6, 1033e-6};
120      for(unsigned int ix=0;ix<4;++ix)
121        scale(_h[ix],1./tau[ix/2]/ *_c[ix/2]);
122    }
123
124    /// @}
125
126
127    /// @name Histograms
128    /// @{
129    Histo1DPtr _h[4];
130    CounterPtr _c[2];
131    /// @}
132
133
134  };
135
136
137  RIVET_DECLARE_PLUGIN(BESIII_2024_I2819140);
138
139}