1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/FinalState.hh"
  5#include "Rivet/Projections/ChargedFinalState.hh"
  6#include "Rivet/Projections/UnstableParticles.hh"
  7
  8namespace Rivet {
  9
 10
 11  /// @brief OPAL K*0 fragmentation function paper
 12  ///
 13  /// @author Peter Richardson
 14  class OPAL_1997_I447146 : public Analysis {
 15  public:
 16
 17    RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1997_I447146);
 18
 19
 20    /// @name Analysis methods
 21    /// @{
 22
 23    void init() {
 24      declare(Beam(), "Beams");
 25      declare(ChargedFinalState(), "FS");
 26      declare(UnstableParticles(), "UFS");
 27      book(_histXeK0, 1, 1, 1);
 28      const vector<double> edges{0., 0.01, 0.03, 0.1, 0.125, 0.14, 0.16, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0};
 29      book(_h_ctheta, edges);
 30      book(_h_alpha, edges);
 31      for (size_t ix=0; ix < _h_ctheta->numBins(); ++ix) {
 32        string suff = std::to_string(ix);
 33        if (suff.length() == 1)  suff = "0"+suff;
 34        book(_h_ctheta->bin(ix+1), "ctheta_"+suff, 20, -1.0, 1.0);
 35        book(_h_alpha->bin(ix+1), "alpha_"+suff, 20, 0.0, 0.5*M_PI);
 36      }
 37      book(_h_ctheta_large,"ctheta_large", 20,-1.0, 1.0);
 38
 39
 40      book(_h_alpha_low, {0.3, 0.4, 0.5, 0.7, 1.0});
 41      book(_h_alpha_high, {0.3, 0.4, 0.5, 0.7, 1.0});
 42      for (size_t ix=0; ix < _h_alpha_low->numBins(); ++ix) {
 43        string suff = std::to_string(ix);
 44        book(_h_alpha_low->bin(ix+1), "alpha_low_"+suff, 20, 0.0, 0.5*M_PI);
 45        book(_h_alpha_high->bin(ix+1), "alpha_high_"+suff, 20, 0.0, 0.5*M_PI);
 46      }
 47      book(_h_alpha_large     ,"_h_alpha_large"     ,20,0.,0.5*M_PI);
 48      book(_h_alpha_large_low ,"_h_alpha_large_low" ,20,0.,0.5*M_PI);
 49      book(_h_alpha_large_high,"_h_alpha_large_high",20,0.,0.5*M_PI);
 50    }
 51
 52    pair<double,double> calcRho(Histo1DPtr hist,unsigned int imode) {
 53      if(hist->numEntries()==0.) return make_pair(0.,0.);
 54      double sum1(0.),sum2(0.);
 55      for (const auto& bin : hist->bins() ) {
 56        double Oi = bin.sumW();
 57        if(Oi==0.) continue;
 58        double ai,bi;
 59        if(imode==0) {
 60          ai = 0.25*(bin.xMax()*(3.-sqr(bin.xMax())) - bin.xMin()*(3.-sqr(bin.xMin())));
 61          bi = 0.75*(bin.xMin()*(1.-sqr(bin.xMin())) - bin.xMax()*(1.-sqr(bin.xMax())));
 62        }
 63        else {
 64          ai = 2.*(bin.xMax()-bin.xMin())/M_PI;
 65          bi = 2.*(sin(2.*bin.xMax())-sin(2.*bin.xMin()))/M_PI;
 66        }
 67        double Ei = bin.errW();
 68        sum1 += sqr(bi/Ei);
 69        sum2 += bi/sqr(Ei)*(Oi-ai);
 70      }
 71      return make_pair(sum2/sum1,sqrt(1./sum1));
 72    }
 73
 74
 75    void analyze(const Event& e) {
 76      // First, veto on leptonic events by requiring at least 4 charged FS particles
 77      const FinalState& fs = apply<FinalState>(e, "FS");
 78      const size_t numParticles = fs.particles().size();
 79
 80      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
 81      if (numParticles < 2) {
 82        MSG_DEBUG("Failed leptonic event cut");
 83        vetoEvent;
 84      }
 85      MSG_DEBUG("Passed leptonic event cut");
 86
 87      // Get beams and average beam momentum
 88      const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
 89      const double meanBeamMom = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
 90      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
 91      Vector3 axis;
 92      if(beams.first.pid()>0) {
 93        axis = beams.first .momentum().p3().unit();
 94      }
 95      else {
 96        axis = beams.second.momentum().p3().unit();
 97      }
 98
 99      // Final state of unstable particles to get particle spectra
100      const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");
101
102      for (const Particle& p : ufs.particles(Cuts::abspid==313)) {
103        double xp = p.p3().mod()/meanBeamMom;
104        _histXeK0->fill(xp);
105        int sign = p.pid()/313;
106        if(p.children().size()!=2) continue;
107        Particle kaon;
108        if(p.children()[0].pid()==sign*321 && p.children()[1].pid()==-sign*211) {
109          kaon = p.children()[0];
110        }
111        else if(p.children()[1].pid()==sign*321 && p.children()[0].pid()==-sign*211) {
112          kaon = p.children()[1];
113        }
114        else
115          continue;
116        // spin axes
117        Vector3 e1z = p.momentum().p3().unit();
118        Vector3 e1y = e1z.cross(axis).unit();
119        Vector3 e1x = e1y.cross(e1z).unit();
120        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
121        Vector3 axis1 = boost.transform(kaon.momentum()).p3().unit();
122        double ctheta = e1z.dot(axis1);
123        double phi = atan2(e1y.dot(axis1),e1x.dot(axis1));
124        double alpha = abs(abs(phi)-0.5*M_PI);
125        _h_ctheta->fill(xp,ctheta);
126        _h_alpha->fill(xp,alpha );
127        double cBeam = axis.dot(e1z);
128        (cBeam < 0.5 ? _h_alpha_low : _h_alpha_high)->fill(xp,alpha);
129
130        if (xp > 0.3) {
131          _h_ctheta_large->fill(ctheta);
132          _h_alpha_large->fill(alpha);
133          (cBeam < 0.5 ? _h_alpha_large_low : _h_alpha_large_high)->fill(alpha);
134        }
135      }
136    }
137
138
139    /// Finalize
140    void finalize() {
141      scale(_histXeK0, 1./sumOfWeights());
142      const vector<double> x = {0., 0.01 ,0.03 ,0.10 ,0.125,0.14 ,0.16 ,0.20 ,0.30 ,0.40 ,0.50 ,0.70 ,1.00};
143      Estimate1DPtr h_rho00;
144      book(h_rho00,2,1,1);
145      Estimate1DPtr h_rho_off;
146      book(h_rho_off,2,1,2);
147      Estimate1DPtr h_ratio;
148      book(h_ratio,3,1,1);
149      Estimate1DPtr h_off_low;
150      book(h_off_low,4,1,1);
151      Estimate1DPtr h_off_high;
152      book(h_off_high,4,1,2);
153      for (size_t ix=0; ix<_h_ctheta->numBins(); ++ix) {
154        // extract the rho00 component
155        normalize(_h_ctheta->bin(ix+1));
156        pair<double,double> rho00 = calcRho(_h_ctheta->bin(ix+1), 0);
157        h_rho00->bin(ix+1).set(rho00.first, rho00.second);
158
159        // extract the rho 1 -1 component
160        normalize(_h_alpha->bin(ix+1));
161        pair<double,double> rho_off = calcRho(_h_alpha->bin(ix+1), 1);
162        h_rho_off->bin(ix+1).set(rho_off.first, rho_off.second);
163
164        if (ix<8) continue;
165
166        // at large xp also the ratio
167        size_t iy = ix-8;
168        double ratio = rho_off.first/(1.-rho00.first);
169        double dr    = ((rho_off.second - rho00.first*rho_off.second + rho_off.first*rho00.second))/sqr(1.-rho00.first);
170        h_ratio->bin(iy+1).set(ratio, dr);
171        // rho 1 -1 for cos theta <0.5
172        normalize(_h_alpha_low->bin(iy+1));
173        rho_off = calcRho(_h_alpha_low->bin(iy+1), 1);
174        h_off_low->bin(iy+1).set(rho_off.first, rho_off.second);
175        // rho 1 -1 for cos theta >0.5
176        normalize(_h_alpha_high->bin(iy+1));
177        rho_off = calcRho(_h_alpha_high->bin(iy+1), 1);
178        h_off_high->bin(iy+1).set(rho_off.first, rho_off.second);
179
180      }
181      // ratio for xp 0.3
182      normalize(_h_ctheta_large);
183      pair<double,double> rho00 = calcRho(_h_ctheta_large,0);
184      normalize(_h_alpha_large);
185      pair<double,double> rho_off = calcRho(_h_alpha_large,1);
186      double ratio = rho_off.first/(1.-rho00.first);
187      double dr    = ((rho_off.second - rho00.first*rho_off.second + rho_off.first*rho00.second))/sqr(1.-rho00.first);
188      Estimate1DPtr h_ratio_large;
189      book(h_ratio_large,3,2,1);
190      h_ratio_large->bin(1).set(ratio, dr);
191      // rho 1 -1 for xp >0.3 and cos theta < 0.5
192      normalize(_h_alpha_large_low );
193      rho_off = calcRho(_h_alpha_large_low,1);
194      book(h_off_low,4,2,1);
195      h_off_low->bin(1).set(rho_off.first, rho_off.second);
196      // rho 1 -1 for xp >0.3 and cos theta > 0.5
197      normalize(_h_alpha_large_high);
198      rho_off = calcRho(_h_alpha_large_high,1);
199      book(h_off_high,4,2,2);
200      h_off_high->bin(1).set(rho_off.first, rho_off.second);
201    }
202
203    /// @}
204
205
206  private:
207
208    /// @{
209    Histo1DPtr _histXeK0;
210    Histo1DGroupPtr _h_ctheta, _h_alpha, _h_alpha_low, _h_alpha_high;
211    Histo1DPtr  _h_ctheta_large, _h_alpha_large, _h_alpha_large_low, _h_alpha_large_high;
212    /// @}
213
214  };
215
216
217
218  RIVET_DECLARE_ALIASED_PLUGIN(OPAL_1997_I447146, OPAL_1997_S3608263);
219
220}