Rivet analyses referenceARGUS_1992_I335698Hadronic mass spectrum and helicity angle in $\tau^-\to\pi^-\pi^0\nu_\tau$Experiment: ARGUS (DORIS) Inspire ID: 335698 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Hadronic mass spectrum and helicity angle in $\tau^-\to\pi^-\pi^0\nu_\tau$. Corrected data read from figures 3 and 4 in the paper. Source code: ARGUS_1992_I335698.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4#include "Rivet/Projections/DecayedParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief tau -> pi- pi0 nu_tau
10 class ARGUS_1992_I335698 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1992_I335698);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 UnstableParticles ufs = UnstableParticles(Cuts::abspid==15);
24 declare(ufs, "UFS");
25 DecayedParticles TAU(ufs);
26 TAU.addStable(310);
27 TAU.addStable(111);
28 TAU.addStable(221);
29 declare(TAU, "TAU");
30 // hists
31 for (unsigned int ix=0; ix<2; ++ix) {
32 book(_h[ix], 1+ix, 1, 1);
33 }
34 }
35
36
37 /// Perform the per-event analysis
38 void analyze(const Event& event) {
39 DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
40 // loop over particles
41 for (unsigned int ix=0; ix<TAU.decaying().size(); ++ix) {
42 int sign = TAU.decaying()[ix].pid()>0 ? 1 : -1;
43 if (!(TAU.modeMatches(ix,3,mode) || TAU.modeMatches(ix,3,modeCC))) continue;
44 const Particle& pi0 = TAU.decayProducts()[ix].at( 111 )[0];
45 const Particle& pim = TAU.decayProducts()[ix].at(-211*sign)[0];
46 FourMomentum phad = pim.mom()+pi0.mom();
47 _h[0]->fill(phad.mass());
48 LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(phad.betaVec());
49 FourMomentum ppi = boost.transform(pim.mom());
50 const double cTheta = ppi.p3().unit().dot(phad.p3().unit());
51 _h[1]->fill(cTheta);
52 }
53 }
54
55
56 /// Normalise histograms etc., after the run
57 void finalize() {
58 normalize(_h, 1.0, false);
59 }
60
61 /// @}
62
63
64 /// @name Histograms
65 /// @{
66 Histo1DPtr _h[2];
67 const map<PdgId,unsigned int> mode = { { 111,1},{-211,1},{ 16,1}};
68 const map<PdgId,unsigned int> modeCC = { { 111,1},{ 211,1},{-16,1}};
69 /// @}
70
71
72 };
73
74
75 RIVET_DECLARE_PLUGIN(ARGUS_1992_I335698);
76
77}
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