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## Rivet analyses reference

### BABAR_2015_I1334693

Exclusive semileptonic D0 to piminus decays.
Experiment: BABAR (PEP-II)
Inspire ID: 1334693
Status: VALIDATED
Authors:
• Holger Schulz
No references listed
Beams: * *
Beam energies: ANY
Run details:
• Events with D-decays, either particle guns or collisions.

Implementation of Lorentz invariant q2 distributions ("form factor") for semileptonic D0 decays

Source code: BABAR_2015_I1334693.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/UnstableFinalState.hh" namespace Rivet { /// @brief Add a short analysis description here class BABAR_2015_I1334693 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(BABAR_2015_I1334693); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { // Initialise and register projections declare(UnstableFinalState(), "UFS"); // Book histograms _h_q2 = bookHisto1D(1, 1, 1); } // Calculate the Q2 using mother and daugher meson double q2(const Particle& B, int mesonID) { FourMomentum q = B.mom() - filter_select(B.children(), Cuts::pid==mesonID)[0]; return q*q; } // Check for explicit decay into pdgids bool isSemileptonicDecay(const Particle& mother, vector ids) { // Trivial check to ignore any other decays but the one in question modulo photons const Particles children = mother.children(Cuts::pid!=PID::PHOTON); if (children.size()!=ids.size()) return false; // Check for the explicit decay return all(ids, [&](int i){return count(children, hasPID(i))==1;}); } /// Perform the per-event analysis void analyze(const Event& event) { // Loop over D0 mesons foreach(const Particle& p, apply(event, "UFS").particles(Cuts::pid==PID::D0)) { if (isSemileptonicDecay(p, {PID::PIMINUS, PID::POSITRON, PID::NU_E})) { _h_q2->fill(q2(p, PID::PIMINUS), event.weight()); } } } /// Normalise histograms etc., after the run void finalize() { normalize(_h_q2, 375.4); // normalize to data } //@} private: /// @name Histograms //@{ Histo1DPtr _h_q2; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(BABAR_2015_I1334693); }