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BESIII_2019_I1691850

Analysis of $J/\psi$ decays to $\Lambda^0\bar\Lambda^0$
Experiment: BESIII (BEPC)
Inspire ID: 1691850
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Nature Phys. 15 (2019) 631-634
Beams: e- e+
Beam energies: (1.6, 1.6) GeV
Run details:
  • e+e- > J/psi

Analysis of the angular distribution of the baryons, and decay products, produced in $e^+e^-\to J/\psi \to \Lambda^0\bar\Lambda^0$. Gives information about the decay and is useful for testing correlations in hadron decays.

Source code: BESIII_2019_I1691850.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief JPsi > Lambda, Lambdabar
  class BESIII_2019_I1691850 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BESIII_2019_I1691850);

    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(Beam(), "Beams");
      declare(UnstableParticles(), "UFS");
      declare(FinalState(), "FS");

      // Book histograms
      book(_h_T1_p, "T1_p",20,-1.,1.);
      book(_h_T2_p, "T2_p",20,-1.,1.);
      book(_h_T3_p, "T3_p",20,-1.,1.);
      book(_h_T4_p, "T4_p",20,-1.,1.);
      book(_h_T5_p, "T5_p",20,-1.,1.);
           		       
      book(_h_T1_n, "T1_n",20,-1.,1.);
      book(_h_T2_n, "T2_n",20,-1.,1.);
      book(_h_T3_n, "T3_n",20,-1.,1.);
      book(_h_T4_n, "T4_n",20,-1.,1.);
      book(_h_T5_n, "T5_n",20,-1.,1.);
      
      book(_h_cThetaL,"cThetaL",20,-1.,1.);
      
      book(_h_mu_p, "mu_p",20,-1.,1.);
      book(_h_mu_n, "mu_n",20,-1.,1.);
      book(_wsum_p,"TMP/wsum_p");
      book(_wsum_n,"TMP/wsum_n");
    }

    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
      for( const Particle &child : p.children()) {
	if(child.children().empty()) {
	  nRes[child.pid()]-=1;
	  --ncount;
	}
	else
	  findChildren(child,nRes,ncount);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // get the axis, direction of incoming electron
      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
      Vector3 axis;
      if(beams.first.pid()>0)
	axis = beams.first .momentum().p3().unit();
      else
	axis = beams.second.momentum().p3().unit();
      // types of final state particles
      const FinalState& fs = apply<FinalState>(event, "FS");
      map<long,int> nCount;
      int ntotal(0);
      for (const Particle& p :  fs.particles()) {
	nCount[p.pid()] += 1;
	++ntotal;
      }
      // loop over lambda0 baryons
      const UnstableParticles & ufs = apply<UnstableParticles>(event, "UFS");
      Particle Lambda,LamBar;
      bool matched(false);
      for (const Particle& p :  ufs.particles(Cuts::abspid==3122)) {
       	if(p.children().empty()) continue;
       	map<long,int> nRes=nCount;
       	int ncount = ntotal;
       	findChildren(p,nRes,ncount);
       	matched=false;
       	// check for antiparticle
      	for (const Particle& p2 :  ufs.particles(Cuts::pid==-p.pid())) {
      	  if(p2.children().empty()) continue;
      	  map<long,int> nRes2=nRes;
      	  int ncount2 = ncount;
      	  findChildren(p2,nRes2,ncount2);
      	  if(ncount2==0) {
      	    matched = true;
      	    for(auto const & val : nRes2) {
      	      if(val.second!=0) {
      		matched = false;
      		break;
      	      }
      	    }
      	    // fond baryon and antibaryon
      	    if(matched) {
	      if(p.pid()>0) {
		Lambda = p;
		LamBar = p2;
	      }
	      else {
		Lambda = p2;
		LamBar = p;
	      }	
       	      break;
       	    }
       	  }
       	}
      	if(matched) break;
      }
      if(!matched) vetoEvent;
      Particle proton;
      matched = false;
      for (const Particle & p : Lambda.children()) {
	if(p.pid()==2212) {
	  matched=true;
	  proton=p;
	}
      }
      if(!matched) vetoEvent;
      Particle baryon;
      int mode(-1);
      for (const Particle & p : LamBar.children()) {
	if(p.pid()==-2212) {
	  baryon=p;
	  mode=0;
	}
	else if(p.pid()==-2112) {
	  baryon=p;
	  mode=1;
	}
      }
      // boost to the Lambda rest frame
      LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(Lambda.momentum().betaVec());
      Vector3 e1z = Lambda.momentum().p3().unit();
      Vector3 e1y = e1z.cross(axis).unit();
      Vector3 e1x = e1y.cross(e1z).unit();
      Vector3 axis1 = boost1.transform(proton.momentum()).p3().unit();
      double n1x(e1x.dot(axis1)),n1y(e1y.dot(axis1)),n1z(e1z.dot(axis1));
      // boost to the Lambda bar
      LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(LamBar.momentum().betaVec());
      Vector3 axis2 = boost2.transform(baryon.momentum()).p3().unit();
      double n2x(e1x.dot(axis2)),n2y(e1y.dot(axis2)),n2z(e1z.dot(axis2));
      double cosL = axis.dot(Lambda.momentum().p3().unit());
      double sinL = sqrt(1.-sqr(cosL));
      double T1 = sqr(sinL)*n1x*n2x+sqr(cosL)*n1z*n2z;
      double T2 = -sinL*cosL*(n1x*n2z+n1z*n2x);
      double T3 = -sinL*cosL*n1y;
      double T4 = -sinL*cosL*n2y;
      double T5 = n1z*n2z-sqr(sinL)*n1y*n2y;
      double mu = n1y-n2y;
      if(mode==0) {
	_h_T1_p->fill(cosL,T1);
	_h_T2_p->fill(cosL,T2);
	_h_T3_p->fill(cosL,T3);
	_h_T4_p->fill(cosL,T4);
	_h_T5_p->fill(cosL,T5);
	_h_mu_p->fill(cosL,mu);
	_wsum_p->fill();
      }
      else {
	_h_T1_n->fill(cosL,T1);
	_h_T2_n->fill(cosL,T2);
	_h_T3_n->fill(cosL,T3);
	_h_T4_n->fill(cosL,T4);
	_h_T5_n->fill(cosL,T5);
	_h_mu_n->fill(cosL,mu);
	_wsum_n->fill();
      }
      _h_cThetaL->fill(cosL);
    }
    
    pair<double,pair<double,double> > calcAlpha0(Histo1DPtr hist) {
      if(hist->numEntries()==0.) return make_pair(0.,make_pair(0.,0.));
      double d = 3./(pow(hist->xMax(),3)-pow(hist->xMin(),3));
      double c = 3.*(hist->xMax()-hist->xMin())/(pow(hist->xMax(),3)-pow(hist->xMin(),3));
      double sum1(0.),sum2(0.),sum3(0.),sum4(0.),sum5(0.);
      for (auto bin : hist->bins() ) {
       	double Oi = bin.area();
	if(Oi==0.) continue;
	double a =  d*(bin.xMax() - bin.xMin());
	double b = d/3.*(pow(bin.xMax(),3) - pow(bin.xMin(),3));
       	double Ei = bin.areaErr();
	sum1 +=   a*Oi/sqr(Ei);
	sum2 +=   b*Oi/sqr(Ei);
	sum3 += sqr(a)/sqr(Ei);
	sum4 += sqr(b)/sqr(Ei);
	sum5 +=    a*b/sqr(Ei);
      }
      // calculate alpha
      double alpha = (-c*sum1 + sqr(c)*sum2 + sum3 - c*sum5)/(sum1 - c*sum2 + c*sum4 - sum5);
      // and error
      double cc = -pow((sum3 + sqr(c)*sum4 - 2*c*sum5),3);
      double bb = -2*sqr(sum3 + sqr(c)*sum4 - 2*c*sum5)*(sum1 - c*sum2 + c*sum4 - sum5);
      double aa =  sqr(sum1 - c*sum2 + c*sum4 - sum5)*(-sum3 - sqr(c)*sum4 + sqr(sum1 - c*sum2 + c*sum4 - sum5) + 2*c*sum5);      
      double dis = sqr(bb)-4.*aa*cc;
      if(dis>0.) {
	dis = sqrt(dis);
	return make_pair(alpha,make_pair(0.5*(-bb+dis)/aa,-0.5*(-bb-dis)/aa));
      }
      else {
	return make_pair(alpha,make_pair(0.,0.));
      }
    }
    
    pair<double,double> calcCoeff(unsigned int imode,Histo1DPtr hist) {
      if(hist->numEntries()==0.) return make_pair(0.,0.);
      double sum1(0.),sum2(0.);
      for (auto bin : hist->bins() ) {
	double Oi = bin.area();
	if(Oi==0.) continue;
	double ai(0.),bi(0.);
	if(imode==0) {
	  bi = (pow(1.-sqr(bin.xMin()),1.5) - pow(1.-sqr(bin.xMax()),1.5))/3.;
	}
	else if(imode>=2 && imode<=4) {
	  bi = ( pow(bin.xMin(),3)*( -5. + 3.*sqr(bin.xMin()))  +
		 pow(bin.xMax(),3)*(  5. - 3.*sqr(bin.xMax())))/15.;
	}
	else
	  assert(false);
	double Ei = bin.areaErr();
	sum1 += sqr(bi/Ei);
	sum2 += bi/sqr(Ei)*(Oi-ai);
      }
      return make_pair(sum2/sum1,sqrt(1./sum1));
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_cThetaL);
      scale(_h_T1_p,1./ *_wsum_p);
      scale(_h_T2_p,1./ *_wsum_p);
      scale(_h_T3_p,1./ *_wsum_p);
      scale(_h_T4_p,1./ *_wsum_p);
      scale(_h_T5_p,1./ *_wsum_p);
      
      scale(_h_T1_n,1./ *_wsum_n);
      scale(_h_T2_n,1./ *_wsum_n);
      scale(_h_T3_n,1./ *_wsum_n);
      scale(_h_T4_n,1./ *_wsum_n);
      scale(_h_T5_n,1./ *_wsum_n);
      
      scale(_h_mu_p,1./ *_wsum_p);
      scale(_h_mu_n,1./ *_wsum_n);

      // calculate alpha0
      pair<double,pair<double,double> > alpha0 = calcAlpha0(_h_cThetaL);
      Scatter2DPtr _h_alpha0;
      book(_h_alpha0,1,1,1);
      _h_alpha0->addPoint(0.5, alpha0.first, make_pair(0.5,0.5),
			  make_pair(alpha0.second.first,alpha0.second.second) );
      double s2 = -1. + sqr(alpha0.first);
      double s3 = 3 + alpha0.first;
      double s1 = sqr(s3);
      // alpha- and alpha+ from proton data
      pair<double,double> c_T2_p = calcCoeff(2,_h_T2_p);
      pair<double,double> c_T3_p = calcCoeff(3,_h_T3_p);
      pair<double,double> c_T4_p = calcCoeff(4,_h_T4_p);
      double s4 = sqr(c_T2_p.first);
      double s5 = sqr(c_T3_p.first);
      double s6 = sqr(c_T4_p.first);
      double disc = s1*s5*s6*(-9.*s2*s4 + 4.*s1*s5*s6);
      if(disc>=0.) {
	disc = sqrt(disc);
	double aM = sqrt(-1./s2/s6*(2.*s1*s5*s6+disc));
	double aP = c_T4_p.first/c_T3_p.first*aM;
	double aM_M = (2*(alpha0.first*c_T4_p.first*alpha0.second.first + c_T4_p.second*s2)*(disc + 2*s1*s5*s6)
		       - c_T4_p.first*s2*(4*s3*c_T3_p.first*c_T4_p.first*(c_T3_p.first*c_T4_p.first*alpha0.second.first +s3*c_T4_p.first*c_T3_p.second +s3*c_T3_p.first*c_T4_p.second) +
				(disc*(- 9*s2*s3*c_T2_p.first*c_T3_p.first*c_T4_p.first* c_T2_p.second
				       + 9*((1 -  alpha0.first*(3 + 2*alpha0.first))* c_T3_p.first*c_T4_p.first*alpha0.second.first -  s2*s3*c_T4_p.first*c_T3_p.second
					     - s2*s3*c_T3_p.first*c_T4_p.second)* s4
				       + 8*(c_T3_p.first*c_T4_p.first*alpha0.second.first +  s3*c_T4_p.first*c_T3_p.second +  s3*c_T3_p.first*c_T4_p.second)* s1*s5*s6))
				/(4*pow(3 + alpha0.first,3)*pow(c_T3_p.first,3)*pow(c_T4_p.first,3) -9*s2*s3*c_T3_p.first*c_T4_p.first*s4)))/
	  (2.*pow(c_T4_p.first,3)*pow(s2,2)*sqrt(-((disc + 2*s1*s5*s6)/(s2*s6))));
	double aM_P = (2*(alpha0.first*c_T4_p.first*alpha0.second.second + c_T4_p.second*s2)*(disc + 2*s1*s5*s6)
		       - c_T4_p.first*s2*(4*s3*c_T3_p.first*c_T4_p.first*(c_T3_p.first*c_T4_p.first*alpha0.second.second +s3*c_T4_p.first*c_T3_p.second +s3*c_T3_p.first*c_T4_p.second) +
				(disc*(- 9*s2*s3*c_T2_p.first*c_T3_p.first*c_T4_p.first* c_T2_p.second
				       + 9*((1 -  alpha0.first*(3 + 2*alpha0.first))* c_T3_p.first*c_T4_p.first*alpha0.second.second -  s2*s3*c_T4_p.first*c_T3_p.second
					     - s2*s3*c_T3_p.first*c_T4_p.second)* s4
				       + 8*(c_T3_p.first*c_T4_p.first*alpha0.second.second +  s3*c_T4_p.first*c_T3_p.second +  s3*c_T3_p.first*c_T4_p.second)* s1*s5*s6))
				/(4*pow(3 + alpha0.first,3)*pow(c_T3_p.first,3)*pow(c_T4_p.first,3) -9*s2*s3*c_T3_p.first*c_T4_p.first*s4)))/
	  (2.*pow(c_T4_p.first,3)*pow(s2,2)*sqrt(-((disc + 2*s1*s5*s6)/(s2*s6))));
	double aP_M = (c_T4_p.first*sqrt(-((disc + 2*s1*s5*s6)/   (s2*s6)))*
		       (-2*c_T3_p.second -  (2*alpha0.first*c_T3_p.first*alpha0.second.first)/s2 +  (c_T3_p.first*(4*s3*c_T3_p.first*c_T4_p.first*(c_T3_p.first*c_T4_p.first*alpha0.second.first +  s3*c_T4_p.first*c_T3_p.second +  s3*c_T3_p.first*c_T4_p.second)
							    + (disc*(-9*s2*s3*c_T2_p.first*c_T3_p.first*c_T4_p.first* c_T2_p.second
								      +  9*((1 -  alpha0.first*(3 + 2*alpha0.first))* c_T3_p.first*c_T4_p.first*alpha0.second.first -  s2*s3*c_T4_p.first*c_T3_p.second
									     -  s2*s3*c_T3_p.first*c_T4_p.second)* s4 +
								      8*(c_T3_p.first*c_T4_p.first*alpha0.second.first +  s3*c_T4_p.first*c_T3_p.second +  s3*c_T3_p.first*c_T4_p.second)* s1*s5*s6))/
							    (4* pow(3 + alpha0.first,3)* pow(c_T3_p.first,3)* pow(c_T4_p.first,3) -  9*s2*s3*c_T3_p.first*c_T4_p.first*s4)))/
			(disc + 2*s1*s5*s6)))/(2.*pow(c_T3_p.first,2));
	double aP_P = (c_T4_p.first*sqrt(-((disc + 2*s1*s5*s6)/   (s2*s6)))*
		       (-2*c_T3_p.second -  (2*alpha0.first*c_T3_p.first*alpha0.second.second)/s2 +  (c_T3_p.first*(4*s3*c_T3_p.first*c_T4_p.first*(c_T3_p.first*c_T4_p.first*alpha0.second.second +  s3*c_T4_p.first*c_T3_p.second +  s3*c_T3_p.first*c_T4_p.second)
							    + (disc*(-9*s2*s3*c_T2_p.first*c_T3_p.first*c_T4_p.first* c_T2_p.second
								      +  9*((1 -  alpha0.first*(3 + 2*alpha0.first))* c_T3_p.first*c_T4_p.first*alpha0.second.second -  s2*s3*c_T4_p.first*c_T3_p.second
									     -  s2*s3*c_T3_p.first*c_T4_p.second)* s4 +
								      8*(c_T3_p.first*c_T4_p.first*alpha0.second.second +  s3*c_T4_p.first*c_T3_p.second +  s3*c_T3_p.first*c_T4_p.second)* s1*s5*s6))/
							    (4* pow(3 + alpha0.first,3)* pow(c_T3_p.first,3)* pow(c_T4_p.first,3) -  9*s2*s3*c_T3_p.first*c_T4_p.first*s4)))/
			(disc + 2*s1*s5*s6)))/(2.*pow(c_T3_p.first,2));
	Scatter2DPtr _h_alphaM;
	book(_h_alphaM,1,3,1);
	_h_alphaM->addPoint(0.5, aM, make_pair(0.5,0.5),
			    make_pair(-aM_M , -aM_P ) );

	Scatter2DPtr _h_alphaP;
	book(_h_alphaP,1,4,1);
	_h_alphaP->addPoint(0.5, aP, make_pair(0.5,0.5),
			    make_pair(-aP_M , -aP_P  ) );
	// now for Delta
	double sDelta = (-2.*(3. + alpha0.first)*c_T3_p.first)/(aM*sqrt(1 - sqr(alpha0.first)));
	double cDelta = (-3*(3 + alpha0.first)*c_T2_p.first)/(aM*aP*sqrt(1 - sqr(alpha0.first)));

	double Delta = asin(sDelta);
	if(cDelta<0.) Delta = M_PI-Delta;
	double ds_P = (-9*c_T2_p.first*((-1 + alpha0.first)*(1 + alpha0.first)*  (3 + alpha0.first)*c_T3_p.first*c_T4_p.first*c_T2_p.second +  c_T2_p.first*c_T4_p.first*(c_T3_p.first*(alpha0.second.first + 3*alpha0.first*alpha0.second.first) -(-1 + alpha0.first)*(1 + alpha0.first)*(3 + alpha0.first)*c_T3_p.second)
			      -  (-1 + alpha0.first)*(1 + alpha0.first)*  (3 + alpha0.first)*c_T2_p.first*c_T3_p.first*c_T4_p.second)*disc)/
	  (pow(1 - pow(alpha0.first,2),1.5)*pow(c_T4_p.first,3)*pow(-((disc + 2*s1*s5*s6)/   (s2*s6)),1.5)*(-9*s2*s4 + 4*s1*s5*s6));
	double ds_M = (-9*c_T2_p.first*((-1 + alpha0.first)*(1 + alpha0.first)*  (3 + alpha0.first)*c_T3_p.first*c_T4_p.first*c_T2_p.second +  c_T2_p.first*c_T4_p.first*(c_T3_p.first*(alpha0.second.second + 3*alpha0.first*alpha0.second.second) -(-1 + alpha0.first)*(1 + alpha0.first)*(3 + alpha0.first)*c_T3_p.second)
			      -  (-1 + alpha0.first)*(1 + alpha0.first)*  (3 + alpha0.first)*c_T2_p.first*c_T3_p.first*c_T4_p.second)*disc)/
	  (pow(1 - pow(alpha0.first,2),1.5)*pow(c_T4_p.first,3)*pow(-((disc + 2*s1*s5*s6)/   (s2*s6)),1.5)*(-9*s2*s4 + 4*s1*s5*s6));
	ds_P /= sqrt(1.-sqr(sDelta));
	ds_M /= sqrt(1.-sqr(sDelta));
	Scatter2DPtr _h_sin;
	book(_h_sin,1,2,1);
	_h_sin->addPoint(0.5, Delta/M_PI*180., make_pair(0.5,0.5), make_pair( -ds_P/M_PI*180., -ds_M/M_PI*180. ) );
      }
      // alpha 0
      pair<double,double> c_T2_n = calcCoeff(2,_h_T2_n);
      pair<double,double> c_T3_n = calcCoeff(3,_h_T3_n);
      pair<double,double> c_T4_n = calcCoeff(4,_h_T4_n);
      s4 = sqr(c_T2_n.first);
      s5 = sqr(c_T3_n.first);
      s6 = sqr(c_T4_n.first);
      disc = s1*s5*s6*(-9.*s2*s4 + 4.*s1*s5*s6);
      if(disc>=0.) {
	disc = sqrt(disc);
	double aM = sqrt(-1./s2/s6*(2.*s1*s5*s6+disc));
	double a0 = c_T4_n.first/c_T3_n.first*aM;
	double a0_M = (c_T4_n.first*sqrt(-((disc + 2*s1*s5*s6)/   (s2*s6)))*
		       (-2*c_T3_n.second -  (2*alpha0.first*c_T3_n.first*alpha0.second.first)/s2 +  (c_T3_n.first*(4*s3*c_T3_n.first*c_T4_n.first*(c_T3_n.first*c_T4_n.first*alpha0.second.first +  s3*c_T4_n.first*c_T3_n.second +  s3*c_T3_n.first*c_T4_n.second)
							    + (disc*(-9*s2*s3*c_T2_n.first*c_T3_n.first*c_T4_n.first* c_T2_n.second
								      +  9*((1 -  alpha0.first*(3 + 2*alpha0.first))* c_T3_n.first*c_T4_n.first*alpha0.second.first -  s2*s3*c_T4_n.first*c_T3_n.second
									     -  s2*s3*c_T3_n.first*c_T4_n.second)* s4 +
								      8*(c_T3_n.first*c_T4_n.first*alpha0.second.first +  s3*c_T4_n.first*c_T3_n.second +  s3*c_T3_n.first*c_T4_n.second)* s1*s5*s6))/
							    (4* pow(3 + alpha0.first,3)* pow(c_T3_n.first,3)* pow(c_T4_n.first,3) -  9*s2*s3*c_T3_n.first*c_T4_n.first*s4)))/
			(disc + 2*s1*s5*s6)))/(2.*pow(c_T3_n.first,2));
	double a0_P = (c_T4_n.first*sqrt(-((disc + 2*s1*s5*s6)/   (s2*s6)))*
		       (-2*c_T3_n.second -  (2*alpha0.first*c_T3_n.first*alpha0.second.second)/s2 +  (c_T3_n.first*(4*s3*c_T3_n.first*c_T4_n.first*(c_T3_n.first*c_T4_n.first*alpha0.second.second +  s3*c_T4_n.first*c_T3_n.second +  s3*c_T3_n.first*c_T4_n.second)
							    + (disc*(-9*s2*s3*c_T2_n.first*c_T3_n.first*c_T4_n.first* c_T2_n.second
								      +  9*((1 -  alpha0.first*(3 + 2*alpha0.first))* c_T3_n.first*c_T4_n.first*alpha0.second.second -  s2*s3*c_T4_n.first*c_T3_n.second
									     -  s2*s3*c_T3_n.first*c_T4_n.second)* s4 +
								      8*(c_T3_n.first*c_T4_n.first*alpha0.second.second +  s3*c_T4_n.first*c_T3_n.second +  s3*c_T3_n.first*c_T4_n.second)* s1*s5*s6))/
							    (4* pow(3 + alpha0.first,3)* pow(c_T3_n.first,3)* pow(c_T4_n.first,3) -  9*s2*s3*c_T3_n.first*c_T4_n.first*s4)))/
			(disc + 2*s1*s5*s6)))/(2.*pow(c_T3_n.first,2));
	Scatter2DPtr _h_alpha0;
	book(_h_alpha0,1,5,1);
	_h_alpha0->addPoint(0.5, a0, make_pair(0.5,0.5),
			    make_pair(-a0_M , -a0_P ) );
      }
    }

    //@}

    /// @name Histograms
    //@{
    Histo1DPtr _h_T1_p,_h_T2_p,_h_T3_p,_h_T4_p,_h_T5_p;
    Histo1DPtr _h_T1_n,_h_T2_n,_h_T3_n,_h_T4_n,_h_T5_n;
    Histo1DPtr _h_cThetaL;
    Histo1DPtr _h_mu_p,_h_mu_n;
    CounterPtr _wsum_p,_wsum_n;
    //@}

  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(BESIII_2019_I1691850);


}