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BELLE_2020_I1789775

Cross section for $e^+e^-\to D_s^+D^{*-}_{s2}-\text{c.c.}$ between 4.52 and 5.6 GeV
Experiment: BELLE (KEKB)
Inspire ID: 1789775
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 101 (2020) 9, 091101
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to D_s^+D^{*-}_{s2}+\text{c.c.}$ times the branching ratio for $D^{*-}_{s2}\to \bar{D}^0K^-$ for centre-of-mass energies between 4.52 and 5.6 GeV by the BELLE collaboration.

Source code: BELLE_2020_I1789775.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief e+e- -> Ds D_s2
 10  class BELLE_2020_I1789775 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2020_I1789775);
 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      declare(FinalState(), "FS");
 24      declare(UnstableParticles(), "UFS");
 25
 26      // Book histograms
 27      book(_c_Ds    ,"/TMP/c_Ds"    );
 28    }
 29
 30    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 31      for(const Particle &child : p.children()) {
 32	if(child.children().empty()) {
 33	  nRes[child.pid()]-=1;
 34	  --ncount;
 35	}
 36	else
 37	  findChildren(child,nRes,ncount);
 38      }
 39    }
 40
 41    /// Perform the per-event analysis
 42    void analyze(const Event& event) {
 43      const FinalState& fs = apply<FinalState>(event, "FS");
 44      // total analyse final state
 45      map<long,int> nCount;
 46      int ntotal(0);
 47      for (const Particle& p : fs.particles()) {
 48      	nCount[p.pid()] += 1;
 49      	++ntotal;
 50      }
 51      // unstable charm analysis
 52      Particles ds = apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==431 or Cuts::abspid==435);
 53      for(unsigned int ix=0;ix<ds.size();++ix) {
 54	const Particle& p1 = ds[ix];
 55       	int id1 = abs(p1.pid());
 56	// check fs
 57	bool fs = true;
 58	for (const Particle & child : p1.children()) {
 59	  if(child.pid()==p1.pid()) {
 60	    fs = false;
 61	    break;
 62	  }
 63	}
 64      	if(!fs) continue;
 65      	// find the children
 66      	map<long,int> nRes = nCount;
 67      	int ncount = ntotal;
 68      	findChildren(p1,nRes,ncount);
 69      	bool matched=false;
 70       	int sign = p1.pid()/id1;
 71       	for(unsigned int iy=ix+1;iy<ds.size();++iy) {
 72      	  const Particle& p2 = ds[iy];
 73      	  fs = true;
 74      	  for (const Particle & child : p2.children()) {
 75      	    if(child.pid()==p2.pid()) {
 76      	      fs = false;
 77      	      break;
 78      	    }
 79      	  }
 80      	  if(!fs) continue;
 81      	  if(p2.pid()/abs(p2.pid())==sign) continue;
 82	  int id2 = abs(p2.pid());
 83	  if(!p2.parents().empty() && p2.parents()[0].pid()==p1.pid())
 84	    continue;
 85	  map<long,int> nRes2 = nRes;
 86	  int ncount2 = ncount;
 87	  findChildren(p2,nRes2,ncount2);
 88	  if(ncount2!=0) continue;
 89	  matched=true;
 90	  for(auto const & val : nRes2) {
 91	    if(val.second!=0) {
 92	      matched = false;
 93	      break;
 94	    }
 95	  }
 96	  if(matched) {
 97       	    if((id1==431 && id2==435) || (id1==435 && id2==431)) {
 98	      Particle Ds2 = id1==435 ? p1 : p2;
 99	      matched = false;
100	      if(Ds2.children().size()!=2) continue;
101	      if(Ds2.pid()==435 &&
102		 ((Ds2.children()[0].pid()==421 && Ds2.children()[1].pid()==321) ||
103		  (Ds2.children()[1].pid()==421 && Ds2.children()[0].pid()==321) ))
104		matched = true;
105	      else if (Ds2.pid()==-435 &&
106		 ((Ds2.children()[0].pid()==-421 && Ds2.children()[1].pid()==-321) ||
107		  (Ds2.children()[1].pid()==-421 && Ds2.children()[0].pid()==-321) ))
108		matched = true;
109	      if(matched) {
110		_c_Ds->fill();
111		break;
112	      }
113	    }
114	  }
115	}
116	if(matched) break;
117      }
118    }
119
120
121    /// Normalise histograms etc., after the run
122    void finalize() {
123      double fact = crossSection()/ sumOfWeights()/picobarn;
124      double sigma = _c_Ds->val()*fact;
125      double error = _c_Ds->err()*fact;
126      Scatter2D temphisto(refData(1, 1, 1));
127      Scatter2DPtr     mult;
128      book(mult, 1, 1, 1);
129      for (size_t b = 0; b < temphisto.numPoints(); b++) {
130	const double x  = temphisto.point(b).x();
131	pair<double,double> ex = temphisto.point(b).xErrs();
132	pair<double,double> ex2 = ex;
133	if(ex2.first ==0.) ex2. first=0.0001;
134	if(ex2.second==0.) ex2.second=0.0001;
135	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
136	  mult   ->addPoint(x, sigma, ex, make_pair(error,error));
137	}
138	else {
139	  mult   ->addPoint(x, 0., ex, make_pair(0.,.0));
140	}
141      }
142    }
143
144    ///@}
145
146
147    /// @name Histograms
148    ///@{
149    CounterPtr _c_Ds;
150    ///@}
151
152
153  };
154
155
156  RIVET_DECLARE_PLUGIN(BELLE_2020_I1789775);
157
158}