Rivet analyses referenceCLEOII_1995_I400623Spectral functions in $\tau^-\to\pi^-\pi^-\pi^+\pi^0\nu_\tau$Experiment: CLEOII (CESR) Inspire ID: 400623 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the spectral functions for $\tau^-\to\pi^-\pi^-\pi^+\pi^0\nu_\tau$ and $\tau^-\to\pi^-\omega\nu_\tau$, and the helicity angle in $\tau^-\to\pi^-\omega\nu_\tau$. The corrected data were read from figure 3b in the paper. Source code: CLEOII_1995_I400623.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- pi- pi+ pi0
10 class CLEOII_1995_I400623 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1995_I400623);
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 // histograms
31 for (unsigned int ix=0; ix<2; ++ix) {
32 book(_h_spect[ix], 1, 1, 1+ix);
33 }
34 book(_c,"TMP/nTau");
35 }
36
37
38 /// Perform the per-event analysis
39 void analyze(const Event& event) {
40 DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
41 // loop over particles
42 for (unsigned int ix=0; ix<TAU.decaying().size(); ++ix) {
43 _c->fill();
44 int sign = TAU.decaying()[ix].pid()>0 ? 1 : -1;
45 if (!(TAU.modeMatches(ix,5,mode) || TAU.modeMatches(ix,5,modeCC))) continue;
46 const Particle& pi0 = TAU.decayProducts()[ix].at( 111 )[0];
47 const Particles& pim = TAU.decayProducts()[ix].at(-211*sign);
48 const Particle& pip = TAU.decayProducts()[ix].at( 211*sign)[0];
49 FourMomentum phad = pim[0].mom()+pim[1].mom()+pip.mom()+pi0.mom();
50 const double q = phad.mass();
51 const double mtau = TAU.decaying()[ix].mass();
52 _h_spect[0]->fill(phad.mass(),sqr(mtau)*mtau/q/sqr(sqr(mtau)-sqr(q))/(sqr(mtau)+2.*sqr(q)));
53 Particle omega;
54 int iomega=-1;
55 for (unsigned int ix=0; ix<2; ++ix) {
56 Particle parent = pim[ix];
57 while (!parent.parents().empty()) {
58 parent = parent.parents()[0];
59 if (parent.pid()==223) break;
60 }
61 if (parent.pid()==223) {
62 omega=parent;
63 iomega=ix;
64 }
65 }
66 if (iomega<0) continue;
67 _h_spect[1]->fill(phad.mass(),sqr(mtau)*mtau/q/sqr(sqr(mtau)-sqr(q))/(sqr(mtau)+2.*sqr(q)));
68 }
69 }
70
71
72 /// Normalise histograms etc., after the run
73 void finalize() {
74 const double Gamma = 6.582119514e-25/290.3e-15;
75 const double GF = 1.1663787e-5;
76 const double cosC = 0.97373;
77 scale(_h_spect, Gamma*16.*sqr(M_PI)/sqr(GF*cosC)/ *_c);
78 }
79
80 /// @}
81
82
83 /// @name Histograms
84 /// @{
85 Histo1DPtr _h_spect[2];
86 CounterPtr _c;
87 const map<PdgId,unsigned int> mode = { { 111,1},{-211,2},{ 211,1},{ 16,1}};
88 const map<PdgId,unsigned int> modeCC = { { 111,1},{ 211,2},{-211,1},{-16,1}};
89 /// @}
90
91
92 };
93
94
95 RIVET_DECLARE_PLUGIN(CLEOII_1995_I400623);
96
97}
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