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BELLE_2016_I1504055

Angular Analysis of $B\to K^{*}\ell^-\ell^-$
Experiment: BELLE (KEKB)
Inspire ID: 1504055
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.Lett. 118 (2017) 11, 111801
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing B+ and B0, originally Upsilon(4S) decay

Measurement of angular coefficients in $B\to K^{*}\ell^-\ell^-$, the code implements these by taking appropriate moments

Source code: BELLE_2016_I1504055.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  B -> K* l+l-
 10  class BELLE_2016_I1504055 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2016_I1504055);
 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==511 or
 24						Cuts::abspid==521);
 25      declare(ufs, "UFS");
 26      DecayedParticles BB(ufs);
 27      BB.addStable(   443);
 28      BB.addStable(100443);
 29      BB.addStable( 313);
 30      BB.addStable( 323);
 31      BB.addStable(-313);
 32      BB.addStable(-323);
 33      declare(BB, "BB");
 34      for(unsigned int ix=0;ix<2;++ix) {
 35	for(unsigned int iy=0;iy<6;++iy) {
 36	  book(_p_P[ix][iy],"TMP/p_P_"+toString(ix)+"_"+toString(iy),refData(1,1+ix,1+iy));
 37	  if(iy>1) continue;
 38	  book(_p_Q[ix][iy],"TMP/p_Q_"+toString(ix)+"_"+toString(iy),refData(2,1+ix,1+iy));
 39	}
 40      }
 41      book(_FL,"TMP/FL");
 42      book(_norm,"TMP/norm");
 43    }
 44
 45
 46    /// Perform the per-event analysis
 47    void analyze(const Event& event) {
 48      static const map<PdgId,unsigned int> & mode1   = { { 323,1},{ 13,1}, {-13,1}};
 49      static const map<PdgId,unsigned int> & mode1CC = { {-323,1},{ 13,1}, {-13,1}};
 50      static const map<PdgId,unsigned int> & mode2   = { { 313,1},{ 13,1}, {-13,1}};
 51      static const map<PdgId,unsigned int> & mode2CC = { {-313,1},{ 13,1}, {-13,1}};
 52      static const map<PdgId,unsigned int> & mode3   = { { 323,1},{ 11,1}, {-11,1}};
 53      static const map<PdgId,unsigned int> & mode3CC = { {-323,1},{ 11,1}, {-11,1}};
 54      static const map<PdgId,unsigned int> & mode4   = { { 313,1},{ 11,1}, {-11,1}};
 55      static const map<PdgId,unsigned int> & mode4CC = { {-313,1},{ 11,1}, {-11,1}};
 56      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
 57      // loop over particles
 58      for(unsigned int ix=0;ix<BB.decaying().size();++ix) {
 59      	int imode=0;
 60      	if ((BB.decaying()[ix].pid()>0 && BB.modeMatches(ix,3,mode1)) ||
 61	    (BB.decaying()[ix].pid()<0 && BB.modeMatches(ix,3,mode1CC)))       imode=0;
 62	else if ((BB.decaying()[ix].pid()>0 && BB.modeMatches(ix,3,mode2)) ||
 63		 (BB.decaying()[ix].pid()<0 && BB.modeMatches(ix,3,mode2CC)))  imode=1;
 64      	else if ((BB.decaying()[ix].pid()>0 && BB.modeMatches(ix,3,mode3)) ||
 65		 (BB.decaying()[ix].pid()<0 && BB.modeMatches(ix,3,mode3CC)))  imode=2;
 66      	else if ((BB.decaying()[ix].pid()>0 && BB.modeMatches(ix,3,mode4)) ||
 67		 (BB.decaying()[ix].pid()<0 && BB.modeMatches(ix,3,mode4CC)))  imode=3;
 68      	else continue;
 69      	int il = imode<2 ? 13 : 11;
 70	int sign = BB.decaying()[ix].pid()>0 ? 1 : -1;
 71      	const Particle & lp = BB.decayProducts()[ix].at(-sign*il)[0];
 72      	const Particle & lm = BB.decayProducts()[ix].at( sign*il)[0];
 73      	double qq = (lp.momentum()+lm.momentum()).mass2();
 74	int iK = BB.decaying()[ix].abspid()==521 ? 323 : 313;
 75	iK *=  BB.decaying()[ix].pid()/BB.decaying()[ix].abspid();
 76	const Particle & Kstar = BB.decayProducts()[ix].at( iK)[0];
 77	if(Kstar.children().size()!=2) continue;
 78	Particle KK;
 79	if(Kstar.abspid()==313) {
 80	  if(Kstar.children()[0].abspid()==321 &&
 81	     Kstar.children()[1].abspid()==211)
 82	    KK = Kstar.children()[0];
 83	  else if(Kstar.children()[1].abspid()==321 &&
 84		  Kstar.children()[0].abspid()==211)
 85	    KK = Kstar.children()[1];
 86	  else continue;
 87	}
 88	else {
 89	  if(Kstar.children()[0].abspid()==311 &&
 90	     Kstar.children()[1].abspid()==211)
 91	    KK = Kstar.children()[0];
 92	  else if(Kstar.children()[1].abspid()==311 &&
 93		  Kstar.children()[0].abspid()==211)
 94	    KK = Kstar.children()[1];
 95	  else if(Kstar.children()[0].abspid()==310 &&
 96		  Kstar.children()[1].abspid()==211)
 97	    KK = Kstar.children()[0];
 98	  else if(Kstar.children()[1].abspid()==310 &&
 99		  Kstar.children()[0].abspid()==211)
100	    KK = Kstar.children()[1];
101	  else if(Kstar.children()[0].abspid()==321 &&
102		  Kstar.children()[1].abspid()==111 )
103	    KK = Kstar.children()[0];
104	  else if(Kstar.children()[1].abspid()==321 &&
105		  Kstar.children()[0].abspid()==111 )
106	    KK = Kstar.children()[1];
107	  else continue;
108	  if(KK.abspid()==311) {
109	    if(KK.children().size()==1 && KK.children()[0].pid()==310)
110	      KK = KK.children()[0];
111	    else
112	      continue;
113	  }
114	}
115	// first boost to bottom frame
116	const LorentzTransform boost  = LorentzTransform::mkFrameTransformFromBeta(BB.decaying()[ix].momentum().betaVec());
117	FourMomentum plp    = boost.transform(lp   .momentum());
118	FourMomentum plm    = boost.transform(lm   .momentum());
119	FourMomentum pKstar = boost.transform(Kstar.momentum());
120	FourMomentum pK     = boost.transform(KK   .momentum());
121	FourMomentum pB     = boost.transform(BB.decaying()[ix].momentum());
122	// lepton stuff
123	const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta((plp+plm).betaVec());
124	plp = boost2.transform(plp);
125	Vector3 axis1 = boost .transform(pB ).p3().unit();
126	double cThetaL = plp.p3().unit().dot(axis1);
127	Vector3 Trans1 = plp.p3() - cThetaL*plp.p3().mod()*axis1;
128	// kaon stuff
129	const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
130	pK = boost3.transform(pK);
131	Vector3 axis2 = boost .transform(pB ).p3().unit();
132	double cThetaK = pK.p3().unit().dot(axis2);
133	double FL = .5*(5.*sqr(cThetaK)-1.);
134	Vector3 Trans2 = pK.p3() - cThetaK*pK.p3().mod()*axis2;
135	double phi = atan2(Trans1.cross(Trans2).dot(axis2),Trans1.dot(Trans2));
136	double sThetaL = sqrt(1.-sqr(cThetaL));
137	double sThetaK = sqrt(1.-sqr(cThetaK));
138	double S4 = 12.5*cThetaL*sThetaL*cThetaK*sThetaK*cos(phi);
139	double S5 = 5.*cThetaK*sThetaK*sThetaL*sin(phi);
140	_FL->fill(FL);
141	_norm->fill();
142	for(unsigned int ix=0;ix<2;++ix) {
143	  _p_P[ix][0]->fill(qq,S4);
144	  _p_P[ix][3]->fill(qq,S5);
145	  if(il==11) {
146	    _p_P[ix][1]->fill(qq,S4);
147	    _p_P[ix][4]->fill(qq,S5);
148	    _p_Q[ix][0]->fill(qq,-S4);
149	    _p_Q[ix][1]->fill(qq,-S5);
150	  }
151	  else {
152	    _p_P[ix][2]->fill(qq,S4);
153	    _p_P[ix][5]->fill(qq,S5);
154	    _p_Q[ix][0]->fill(qq,S4);
155	    _p_Q[ix][1]->fill(qq,S5);
156	  }
157	}
158      }
159    }
160
161
162    /// Normalise histograms etc., after the run
163    void finalize() {
164      Estimate0D R = *_FL/ *_norm;
165      double fl = R.val();
166      double fact = 1./sqrt(fl*(1.-fl));
167      for(unsigned int ix=0;ix<2;++ix) {
168        for(unsigned int iy=0;iy<6;++iy) {
169          Estimate1DPtr tmp;
170          book(tmp,1,1+ix,1+iy);
171          barchart(_p_P[ix][iy],tmp);
172          scale(tmp,fact);
173	  if(iy>1) continue;
174          book(tmp,2,1+ix,1+iy);
175          barchart(_p_Q[ix][iy],tmp);
176          scale(tmp,fact);
177        }
178      }
179    }
180
181    /// @}
182
183
184    /// @name Histograms
185    /// @{
186    Profile1DPtr _p_P[2][6],_p_Q[2][2];
187    CounterPtr _FL,_norm;
188    /// @}
189
190  };
191
192
193  RIVET_DECLARE_PLUGIN(BELLE_2016_I1504055);
194
195}