rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

ALEPH_1996_I421984

Tau decays to $\omega\pi^-$ and $\omega\pi^-\pi^0$
Experiment: ALEPH (LEP)
Inspire ID: 421984
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Z.Phys. C74 (1997) 263-273
Beams: * *
Beam energies: ANY
Run details:
  • any process producing tau leptons

Measurement of mass spectra in the tau lepton decays $\tau^-\to\nu_\tau \pi^-\pi^+\pi^-\pi^0$ and $\tau^-\to\nu_\tau \pi^-\pi^0\pi^+\pi^-\pi^0$

Source code: ALEPH_1996_I421984.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh" 
  4
  5namespace Rivet {
  6
  7
  8  /// @brief tau -> omega pi(pi)
  9  class ALEPH_1996_I421984 : public Analysis {
 10  public:
 11
 12    /// Constructor
 13    RIVET_DEFAULT_ANALYSIS_CTOR(ALEPH_1996_I421984);
 14
 15
 16    /// @name Analysis methods
 17    //@{
 18
 19    /// Book histograms and initialise projections before the run
 20    void init() {
 21
 22      // Initialise and register projections
 23      declare(UnstableParticles(), "UFS");
 24
 25      // Book histograms
 26      book(_h_omegapi_momega[0], 1, 1, 1);
 27      book(_h_omegapi_momega[1], 2, 1, 1);
 28      book(_h_omegapi_momegapi,  3, 1, 1);
 29      book(_h_omegapipi_momega , 6, 1, 1);
 30    }
 31
 32    void findDecayProducts(const Particle &mother, unsigned int & nstable,
 33                           Particles& pip, Particles& pim, Particles & pi0) {
 34      for (const Particle &p : mother.children()) {
 35        long id = p.pid();
 36        if (id == PID::PI0 ) {
 37	  pi0.push_back(p);
 38          ++nstable;
 39	}
 40        else if (id == PID::K0S || id == PID::K0L)
 41          ++nstable;
 42        else if (id == PID::PIPLUS) {
 43          pip.push_back(p);
 44          ++nstable;
 45        }
 46        else if (id == PID::PIMINUS) {
 47          pim.push_back(p);
 48          ++nstable;
 49        }
 50        else if (id == PID::KPLUS) {
 51          ++nstable;
 52        }
 53        else if (id == PID::KMINUS) {
 54          ++nstable;
 55        }
 56        else if (!p.children().empty()) {
 57          findDecayProducts(p, nstable, pip, pim, pi0);
 58        }
 59        else  ++nstable;
 60      }
 61    }
 62
 63    /// Perform the per-event analysis
 64    void analyze(const Event& event) {
 65      // Find the taus
 66      Particles taus;
 67      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::TAU)) {
 68        Particles pip, pim, pi0;
 69        unsigned int nstable = 0;
 70        // Find the decay products we want
 71        findDecayProducts(p, nstable, pip, pim, pi0);
 72        if (p.pid() < 0) {
 73          swap(pip, pim);
 74        }
 75	if(nstable==5&&pip.size()==1&&pim.size()==2&&pi0.size()==1) {
 76	  for(unsigned int ix=0;ix<2;++ix) {
 77	    double momega = (pim[ix].momentum()+pip[0].momentum()+pi0[0].momentum()).mass();
 78	    _h_omegapi_momega[0]->fill(momega);
 79	    _h_omegapi_momega[1]->fill(momega);
 80	  }
 81	  double mtotal = (pim[0].momentum()+pim[1].momentum()+pip[0].momentum()+pi0[0].momentum()).mass();
 82	  _h_omegapi_momegapi->fill(mtotal);
 83	}
 84	else if(nstable==6&&pip.size()==1&&pim.size()==2&&pi0.size()==2) {
 85	  for(unsigned int ix=0;ix<2;++ix) {
 86	    for(unsigned int iy=0;iy<2;++iy) {
 87	      double momega = (pim[ix].momentum()+pip[0].momentum()+pi0[iy].momentum()).mass();
 88	      _h_omegapipi_momega->fill(momega);
 89	    }
 90	  }
 91	}
 92      }
 93    }
 94
 95
 96    /// Normalise histograms etc., after the run
 97    void finalize() {
 98
 99      // normalized measurement
100      normalize(_h_omegapi_momegapi);
101      // normalize to integral of data
102      normalize(_h_omegapi_momega[0],4164.8*0.01 );
103      normalize(_h_omegapi_momega[1],5936.3*0.01 );
104      normalize(_h_omegapipi_momega ,1967.6*0.035);
105    }
106
107    //@}
108
109
110    /// @name Histograms
111    //@{
112    Histo1DPtr _h_omegapi_momega[2], _h_omegapi_momegapi,_h_omegapipi_momega;
113    //@}
114
115
116  };
117
118
119  // The hook for the plugin system
120  RIVET_DECLARE_PLUGIN(ALEPH_1996_I421984);
121
122
123}