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BABAR_2012_I1185407

Mass distributions in $\tau^-\to2\pi^-\pi^+3\pi^0\nu_\tau$, $3\pi^-2\pi^+\nu_\tau$ and $3\pi^-2\pi^+\pi^0\nu_\tau$
Experiment: BABAR (PEP-II)
Inspire ID: 1185407
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 86 (2012) 092010
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing tau leptons, originally e+e-

Measurement of mass distributions in $\tau^-\to2\pi^-\pi^+3\pi^0\nu_\tau$, $3\pi^-2\pi^+\nu_\tau$ and $3\pi^-2\pi^+\pi^0\nu_\tau$. The data were read from the plots in the paper and are not corrected, although the backgrounds given in the paper have been subtracted. The plots should therefore only be used for qualitative comparisons however the data is useful as there are not corrected distributions for this decay mode.

Source code: BABAR_2012_I1185407.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5#include "Rivet/Projections/DecayedParticles.hh"
  6
  7namespace Rivet {
  8
  9
 10  /// @brief tau -> 5 and 5 pion final states
 11  class BABAR_2012_I1185407 : public Analysis {
 12  public:
 13
 14    /// Constructor
 15    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2012_I1185407);
 16
 17
 18    /// @name Analysis methods
 19    /// @{
 20
 21    /// Book histograms and initialise projections before the run
 22    void init() {
 23      // Initialise and register projections
 24      UnstableParticles ufs = UnstableParticles(Cuts::abspid==15);
 25      declare(ufs, "UFS");
 26      DecayedParticles TAU(ufs);
 27      TAU.addStable(310);
 28      TAU.addStable(111);
 29      declare(TAU, "TAU");
 30      // histogram
 31      for(unsigned int ix=0;ix<4;++ix) {
 32	book(_h_6pi[ix],3,1,1+ix);
 33	if(ix>2) continue;
 34	book(_h_3pi[ix],1,1,1+ix);
 35	book(_h_5pi[ix],2,1,1+ix);
 36      }
 37    }
 38
 39
 40    /// Perform the per-event analysis
 41    void analyze(const Event& event) {
 42      static const map<PdgId,unsigned int> & mode1   = { {-211,2}, { 211,1},{111,3},{ 16,1}};
 43      static const map<PdgId,unsigned int> & mode1CC = { { 211,2}, {-211,1},{111,3},{-16,1}};
 44      static const map<PdgId,unsigned int> & mode2   = { {-211,3}, { 211,2},{ 16,1}};
 45      static const map<PdgId,unsigned int> & mode2CC = { { 211,3}, {-211,2},{-16,1}};
 46      static const map<PdgId,unsigned int> & mode3   = { {-211,3}, { 211,2},{111,1},{ 16,1}};
 47      static const map<PdgId,unsigned int> & mode3CC = { { 211,3}, {-211,2},{111,1},{-16,1}};
 48      DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
 49      // loop over particles
 50      for(unsigned int ix=0;ix<TAU.decaying().size();++ix) {
 51      	int sign = TAU.decaying()[ix].pid()>0 ? 1 : -1;
 52	int imode=-1;
 53      	if(TAU.modeMatches(ix,7,mode1  ) ||
 54	   TAU.modeMatches(ix,7,mode1CC))      imode = 0;
 55	else if(TAU.modeMatches(ix,6,mode2  ) ||
 56		TAU.modeMatches(ix,6,mode2CC)) imode = 1;
 57	else if(TAU.modeMatches(ix,7,mode3  ) ||
 58		TAU.modeMatches(ix,7,mode3CC)) imode = 2;
 59	else continue;
 60      	const Particles & pip = TAU.decayProducts()[ix].at( 211*sign);
 61	const Particles & pim = TAU.decayProducts()[ix].at(-211*sign);
 62	FourMomentum ptotal;
 63	for(unsigned int ix=0;ix<pim.size();++ix) ptotal +=pim[ix].momentum();
 64	for(unsigned int ix=0;ix<pip.size();++ix) ptotal +=pip[ix].momentum();
 65	if(imode==1) {
 66	  _h_5pi[2]->fill(ptotal.mass());
 67	  for(unsigned int ix=0;ix<pim.size();++ix) {
 68	    _h_5pi[1]->fill((ptotal-pim[ix].momentum()).mass());
 69	    for(unsigned int iy=0;iy<pip.size();++iy) {
 70	      _h_5pi[0]->fill((pim[ix].momentum()+pip[iy].momentum()).mass());
 71	    }
 72	  }
 73	}
 74	else {
 75	  const Particles  & pi0 = TAU.decayProducts()[ix].at(111);
 76	  FourMomentum ppi0;
 77	  for(unsigned int ix=0;ix<pi0.size();++ix) ppi0 +=pi0[ix].momentum();
 78	  ptotal+=ppi0;
 79	  if(imode==0 ) {
 80	    _h_3pi[0]->fill(ppi0.mass());
 81	    _h_3pi[2]->fill(ptotal.mass());
 82	    for(unsigned int ix=0;ix<pim.size();++ix) {
 83	      for(unsigned int iy=0;iy<pi0.size();++iy) {
 84		_h_3pi[1]->fill((pip[0].momentum()+pim[ix].momentum()+pi0[iy].momentum()).mass());
 85	      }
 86	    }	    
 87	  }
 88	  else {
 89	    _h_6pi[3]->fill(ptotal.mass());
 90	    for(unsigned int ix=0;ix<pim.size();++ix) {
 91	      _h_6pi[2]->fill((ptotal-pim[ix].momentum()).mass());
 92	      for(unsigned int iy=0;iy<pip.size();++iy) {
 93		_h_6pi[0]->fill((pim[ix].momentum()+pip[iy].momentum()).mass());
 94		_h_6pi[1]->fill((pim[ix].momentum()+pip[iy].momentum()+pi0[0].momentum()).mass());
 95	      }
 96	    }
 97	  }
 98	}
 99      }
100    }
101
102    /// Normalise histograms etc., after the run
103    void finalize() {
104      for(unsigned int ix=0;ix<4;++ix) {
105	normalize(_h_6pi[ix]);
106	if(ix>2) continue;
107	normalize(_h_3pi[ix]);
108	normalize(_h_5pi[ix]);
109      }
110    }
111
112    /// @}
113
114
115    /// @name Histograms
116    /// @{
117    Histo1DPtr _h_3pi[3],_h_5pi[3],_h_6pi[4];
118    /// @}
119
120
121  };
122
123
124  RIVET_DECLARE_PLUGIN(BABAR_2012_I1185407);
125
126}