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## Rivet analyses reference

### BABAR_2006_I714448

Pion Mass Spectrum in $\Upsilon(4S)\to\Upsilon(1,2S)\pi^+\pi^-$
Experiment: BABAR (PEP-II)
Inspire ID: 714448
Status: VALIDATED
Authors:
• Peter Richardson
References:
• Phys.Rev.Lett. 96 (2006) 232001
Beams: * *
Beam energies: ANY
Run details:
• Any process producing Upsilon(4S), original e+e-

Measurement of the $\pi^+\pi^-$ mass Spectrum in $\Upsilon(4S)\to\Upsilon(1,2S)\pi^+\pi^-$ decays.

Source code: BABAR_2006_I714448.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 84 85 86 87 88 89 90 91 92 93 94 95 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/UnstableParticles.hh" namespace Rivet { /// @brief Add a short analysis description here class BABAR_2006_I714448 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(BABAR_2006_I714448); /// @name Analysis methods ///@{ /// Book histograms and initialise projections before the run void init() { // Initialise and register projections declare(UnstableParticles(),"UFS"); book(_h_1S, 1, 1, 1); book(_h_2S, 1, 1, 2); } void findDecayProducts(const Particle & mother, unsigned int & nstable, Particles& pip, Particles& pim, Particles & onium) { for(const Particle & p : mother.children()) { int id = p.pid(); if ( id == PID::PIMINUS) { pim.push_back(p); ++nstable; } else if (id == PID::PIPLUS) { pip.push_back(p); ++nstable; } else if (abs(id)%1000==553) { onium.push_back(p); ++nstable; } else if ( !p.children().empty() ) { findDecayProducts(p,nstable,pip,pim,onium); } else ++nstable; } } /// Perform the per-event analysis void analyze(const Event& event) { // loop over unstable particles for(const Particle& ups : apply(event, "UFS").particles(Cuts::pid==300553)) { unsigned int nstable(0); Particles pip, pim, onium; findDecayProducts(ups,nstable,pip,pim,onium); // check for onium if(onium.size() !=1 || nstable !=3) continue; // check for pipi if( ! (pip.size()==1 && pim.size() ==1) ) continue; FourMomentum q = pip[0].momentum()+pim[0].momentum(); if(onium[0].pid()==553) _h_1S->fill(q.mass()); else if(onium[0].pid()==100553) _h_2S->fill(q.mass()); } } /// Normalise histograms etc., after the run void finalize() { normalize(_h_1S); normalize(_h_2S); } ///@} /// @name Histograms ///@{ Histo1DPtr _h_1S,_h_2S; ///@} }; DECLARE_RIVET_PLUGIN(BABAR_2006_I714448); }