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## Rivet analyses reference

### ARGUS_1989_I262415

Spectra for the production of $\Lambda^0(1520)$ in $e^+e^-$ collisions in the continuum at 10 GeV and the $\Upsilon_1$
Experiment: ARGUS (DORIS)
Inspire ID: 262415
Status: VALIDATED
Authors:
• Peter Richardson
References:
• Phys.Lett. B215 (1988) 429-434, 1988
Beams: e- e+
Beam energies: (4.7, 4.7); (5.0, 5.0) GeV
Run details:
• $e^+ e^-$ analysis near the $\Upsilon$ resonances

Spectra for the production of $\Lambda^0(1520)$ in $e^+e^-$ collisions. Data are taken on the $\Upsilon(1S)$ and in the nearby continuum.

Source code: ARGUS_1989_I262415.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 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/UnstableParticles.hh" namespace Rivet { /// @brief Lambda(1520) production class ARGUS_1989_I262415 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(ARGUS_1989_I262415); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { // Initialise and register projections declare(UnstableParticles(), "UFS"); // Book histograms book(_h_ups1, 3, 1, 1); book(_h_cont, 4, 1, 1); book(_weightSum_cont,"TMP/weightSum_cont"); book(_weightSum_Ups1,"TMP/weightSum_Ups1"); } /// Recursively walk the decay tree to find decay products of @a p void findDecayProducts(Particle mother, Particles& unstable) { for(const Particle & p: mother.children()) { const int id = p.pid(); if(id == 3124) { unstable.push_back(p); } if(!p.children().empty()) findDecayProducts(p, unstable); } } /// Perform the per-event analysis void analyze(const Event& event) { // Find the Upsilons among the unstables const UnstableParticles& ufs = apply(event, "UFS"); Particles upsilons = ufs.particles(Cuts::pid==553); // Continuum if (upsilons.empty()) { MSG_DEBUG("No Upsilons found => continuum event"); _weightSum_cont->fill(); for (const Particle& p : ufs.particles(Cuts::abspid==3124)) { const double xp = 2.*p.E()/sqrtS(); const double beta = p.p3().mod() / p.E(); _h_cont->fill(xp,1./beta); } } // Upsilon(s) found else { MSG_DEBUG("Upsilons found => resonance event"); for (const Particle& ups : upsilons) { _weightSum_Ups1->fill(); Particles unstable; // Find the decay products we want findDecayProducts(ups, unstable); LorentzTransform cms_boost; if (ups.p3().mod() > 1*MeV) cms_boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec()); const double mass = ups.mass(); // loop over decay products for(const Particle& p : unstable) { const FourMomentum p2 = cms_boost.transform(p.momentum()); const double xp = 2.*p2.E()/mass; const double beta = p2.p3().mod()/p2.E(); _h_ups1->fill(xp,1./beta); } } } } /// Normalise histograms etc., after the run void finalize() { if (_weightSum_cont->val() > 0.) { scale(_h_cont, 1./ *_weightSum_cont); } if (_weightSum_Ups1->val() > 0.) { scale(_h_ups1, 1./ *_weightSum_Ups1); } } //@} /// @name Histograms //@{ Histo1DPtr _h_ups1, _h_cont; CounterPtr _weightSum_cont,_weightSum_Ups1; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(ARGUS_1989_I262415); }