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## Rivet analyses reference

### BELLE_2006_I725750

$\phi K$ mass distribution in $\tau\to\phi K^-\nu_\tau$
Experiment: BELLE (KEKB)
Inspire ID: 725750
Status: VALIDATED
Authors:
• Peter Richardson
References:
• Phys.Lett. B643 (2006) 5-10
Beams: * *
Beam energies: ANY
Run details:
• any process producing tau leptons

Measurement of the $\phi K$ mass distribution in $\tau\to\phi K^-\nu_tau$ by BELLE

Source code: BELLE_2006_I725750.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 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/UnstableParticles.hh" namespace Rivet { /// @brief tau -> K phi class BELLE_2006_I725750 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(BELLE_2006_I725750); /// @name Analysis methods ///@{ /// Book histograms and initialise projections before the run void init() { declare(UnstableParticles(), "UFS"); book(_hist, 1, 1, 1); } void findDecayProducts(const Particle & mother, unsigned int & nstable, Particles& phi, Particles& K) { for(const Particle & p : mother.children()) { long id = p.abspid(); if (id == PID::PHI ) { phi.push_back(p); ++nstable; } else if (id == PID::KPLUS) { K.push_back(p); ++nstable; } else if ( !p.children().empty() ) { findDecayProducts(p, nstable, phi,K); } else ++nstable; } } /// Perform the per-event analysis void analyze(const Event& event) { const UnstableParticles& ufs = apply(event, "UFS"); for (const Particle& p : ufs.particles(Cuts::abspid==PID::TAU)) { Particles phi, K; unsigned int nstable = 0; // find the decay products we want findDecayProducts(p, nstable, phi, K); if (nstable != 3) continue; // K phi if (K.size() == 1 && phi.size() == 1) _hist->fill((phi[0].momentum()+K[0].momentum()).mass()); } } /// Normalise histograms etc., after the run void finalize() { normalize(_hist); } ///@} /// @name Histograms ///@{ Histo1DPtr _hist; ///@} }; DECLARE_RIVET_PLUGIN(BELLE_2006_I725750); }