1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5#include "Rivet/Projections/Thrust.hh"
  6#include "Rivet/Projections/ChargedFinalState.hh"
  7
  8namespace Rivet {
  9
 10
 11  /// @brief Lambda polarization at LEP1
 12  class OPAL_1997_I447188 : public Analysis {
 13  public:
 14
 15    /// Constructor
 16    RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1997_I447188);
 17
 18
 19    /// @name Analysis methods
 20    /// @{
 21
 22    /// Book histograms and initialise projections before the run
 23    void init() {
 24
 25      // Initialise and register projections
 26      declare(Beam(), "Beams");
 27      const ChargedFinalState cfs;
 28      const Thrust thrust(cfs);
 29      declare(thrust, "Thrust");
 30      declare(UnstableParticles(), "UFS");
 31
 32      // Book the histograms
 33      const vector<double> edges{0.027, 0.05, 0.08, 0.09, 0.1, 0.15, 0.2, 0.3, 0.4, 1.0};
 34      book(_h_ctheta, edges); size_t iy = 1;
 35      for (auto& b : _h_ctheta->bins()) {
 36        if (b.index() == 2 || b.index() == 5 || b.index() == 7) {
 37          book(b, 4, 1, iy++);
 38        }
 39        else {
 40          book(b , "/TMP/ctheta_"+std::to_string(b.index()-1), 20 , -1.0, 1.0);
 41        }
 42      }
 43      book(_h_ctheta_large, 4, 1, 4);
 44
 45      book(_h_cphi, {0.0, 0.3, 0.6, 0.9, 1.2, 1.5});
 46      book(_h_cphi->bin(1), "/TMP/cphiP_0", 10, 0.0, 1.0);
 47      book(_h_cphi->bin(2), 5, 1, 1);
 48      book(_h_cphi->bin(3), 5, 1, 2);
 49      book(_h_cphi->bin(4), "/TMP/cphiP_3", 10, 0.0, 1.0);
 50      book(_h_cphi->bin(5), "/TMP/cphiP_4", 10, 0.0, 1.0);
 51
 52      book(_h_cphi_low, 5, 1, 4);
 53      book(_h_cphi_mid, "/TMP/cphiP_mid", 10, 0.0, 1.0);
 54      book(_h_cphi_high, 5, 1, 3);
 55
 56      book(_h_plus_lam, edges);
 57      book(_h_minus_lam, edges);
 58      for (size_t ix=0; ix<_h_plus_lam->numBins(); ++ix) {
 59        book(_h_plus_lam->bin(ix+1),  "/TMP/lamP_"+std::to_string(ix), 20, -1.0, 1.0);
 60        book(_h_minus_lam->bin(ix+1), "/TMP/lamM_"+std::to_string(ix), 20, -1.0, 1.0);
 61      }
 62      book(_h_plus_lam_large1, "/TMP/lamP_large_1",20,-1.,1.);
 63      book(_h_plus_lam_large2, "/TMP/lamP_large_2",20,-1.,1.);
 64      book(_h_minus_lam_large1, "/TMP/lamM_large_1",20,-1.,1.);
 65      book(_h_minus_lam_large2, "/TMP/lamM_large_2",20,-1.,1.);
 66    }
 67
 68
 69    /// Perform the per-event analysis
 70    void analyze(const Event& event) {
 71
 72      // Get beams and average beam momentum
 73      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
 74      const double meanBeamMom = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
 75      Vector3 beamAxis;
 76      if (beams.first.pid()==-11) {
 77        beamAxis = beams.first .momentum().p3().unit();
 78      }
 79      else {
 80        beamAxis = beams.second.momentum().p3().unit();
 81      }
 82
 83      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
 84      // thrust, to define an axis
 85      const Thrust& thrust = apply<Thrust>(event, "Thrust");
 86      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
 87
 88      for (const Particle & lambda : ufs.particles(Cuts::abspid==3122)) {
 89        double xE = lambda.momentum().t()/meanBeamMom;
 90        int sign = lambda.pid()/3122;
 91        Vector3 axis1 = lambda.momentum().p3().unit();
 92        // assymetry
 93        double cLam = axis1.dot(beamAxis);
 94        if (sign>0)
 95          _h_plus_lam->fill(xE,cLam);
 96        else {
 97          _h_minus_lam->fill(xE,cLam);
 98        }
 99        if(xE>0.15) {
100          if (sign>0)
101            _h_plus_lam_large1 ->fill(cLam);
102          else {
103            _h_minus_lam_large1->fill(cLam);
104          }
105        }
106        if (xE>0.3) {
107          if (sign>0)
108            _h_plus_lam_large2 ->fill(cLam);
109          else {
110            _h_minus_lam_large2->fill(cLam);
111          }
112        }
113        if(lambda.children().size()!=2) continue;
114        // look at the decay products
115        Particle proton,pion;
116        if (lambda.children()[0].pid()==sign*2212 && lambda.children()[1].pid()==-sign*211) {
117          proton = lambda.children()[0];
118          pion   = lambda.children()[1];
119        }
120        else if (lambda.children()[1].pid()==sign*2212 && lambda.children()[0].pid()==-sign*211) {
121          proton = lambda.children()[1];
122          pion   = lambda.children()[0];
123        }
124        else {
125          continue;
126        }
127        // boost to the lambda rest frame
128        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(lambda.momentum().betaVec());
129        FourMomentum pproton = boost.transform(proton.momentum());
130        // longitudinal polarization
131        double ctheta = axis1.dot(pproton.p3().unit());
132        _h_ctheta->fill(xE,ctheta);
133        if(xE>=0.3)  _h_ctheta_large->fill(ctheta);
134        // transverse polarization
135        Vector3 axis2;
136        if (lambda.momentum().p3().dot(thrust.thrustAxis())>=0.) {
137          axis2 = thrust.thrustAxis();
138        }
139        else {
140          axis2 =-thrust.thrustAxis();
141        }
142        Vector3 axis3 = axis2.cross(axis1).unit();
143        double pT = sqrt(sqr(thrust.thrustMajorAxis().dot(lambda.momentum().p3()))+
144                    sqr(thrust.thrustMinorAxis().dot(lambda.momentum().p3())));
145        double cPhi = axis3.dot(pproton.p3().unit());
146        _h_cphi->fill(pT,cPhi);
147        if(pT>0.3) _h_cphi_low->fill(cPhi);
148        if(pT>0.6) _h_cphi_mid->fill(cPhi);
149        if(pT>1.5) _h_cphi_high->fill(cPhi);
150      }
151    }
152
153    pair<double,double> calcAlpha(Histo1DPtr hist) {
154      if (hist->numEntries()==0.) return make_pair(0.,0.);
155      double sum1(0.),sum2(0.);
156      for (const auto& bin : hist->bins()) {
157        double Oi = bin.sumW();
158        if(Oi==0.) continue;
159        double ai = 0.5*(bin.xMax()-bin.xMin());
160        double bi = 0.5*ai*(bin.xMax()+bin.xMin());
161        double Ei = bin.errW();
162        sum1 += sqr(bi/Ei);
163        sum2 += bi/sqr(Ei)*(Oi-ai);
164      }
165      return make_pair(sum2/sum1,sqrt(1./sum1));
166    }
167
168    pair<double,double> calcAsymmetry(Estimate1DPtr hist,unsigned int mode) {
169      double sum1(0.),sum2(0.);
170      for (const auto& bin : hist->bins()) {
171        double Oi = bin.val();
172        if(Oi==0.) continue;
173        double bi;
174        if(mode==0)
175          bi = 0.25*(bin.xMax()-bin.xMin())*(bin.xMax()+bin.xMin());
176        else
177          bi = 4.*(bin.xMax()+bin.xMin())/(3.+sqr(bin.xMax())+bin.xMax()*bin.xMin()+sqr(bin.xMin()));
178        double Ei = bin.errAvg();
179        sum1 += sqr(bi/Ei);
180        sum2 += bi/sqr(Ei)*Oi;
181      }
182      return make_pair(sum2/sum1,sqrt(1./sum1));
183    }
184
185
186    /// Normalise histograms etc., after the run
187    void finalize() {
188      // longitudinal polarization
189      double aLam = 0.642;
190      Estimate1DPtr h_long;
191      book(h_long, 1, 1, 1);
192      for (auto& hist : _h_ctheta->bins()) {
193        normalize(hist);
194        pair<double,double> alpha = calcAlpha(hist);
195        alpha.first  /=aLam;
196        alpha.second /=aLam;
197        h_long->bin(hist.index()).set(100.*alpha.first, 100.*alpha.second);
198      }
199      normalize(_h_ctheta_large);
200      pair<double,double> alpha = calcAlpha(_h_ctheta_large);
201      alpha.first  /=aLam;
202      alpha.second /=aLam;
203      Estimate1DPtr h_long_l;
204      book(h_long_l,1,1,2);
205      h_long_l->bin(1).set(100.*alpha.first, 100.*alpha.second);
206      // transverse polarization
207      Estimate1DPtr h_trans;
208      book(h_trans,2,1,1);
209      for (auto& hist : _h_cphi->bins()) {
210        normalize(hist);
211        pair<double,double> alpha = calcAlpha(hist);
212        alpha.first  /=aLam;
213        alpha.second /=aLam;
214        h_trans->bin(hist.index()).set(100.*alpha.first, 100.*alpha.second);
215      }
216      normalize(_h_cphi_low);
217      alpha = calcAlpha(_h_cphi_low);
218      alpha.first  /=aLam;
219      alpha.second /=aLam;
220      Estimate1DPtr h_trans_low;
221      book(h_trans_low,2,1,2);
222      h_trans_low->bin(1).set(alpha.first, 100.*alpha.second);
223      normalize(_h_cphi_mid);
224      alpha = calcAlpha(_h_cphi_mid);
225      alpha.first  /=aLam;
226      alpha.second /=aLam;
227      Estimate1DPtr h_trans_mid;
228      book(h_trans_mid,2,1,3);
229      h_trans_mid->bin(1).set(alpha.first, 100.*alpha.second);
230      normalize(_h_cphi_high);
231      alpha = calcAlpha(_h_cphi_high);
232      alpha.first  /=aLam;
233      alpha.second /=aLam;
234      Estimate1DPtr h_trans_high;
235      book(h_trans_high,2,1,4);
236      h_trans_high->bin(1).set(alpha.first, 100.*alpha.second);
237      // asyymetry
238      Estimate1DPtr h_asym;
239      book(h_asym, 3, 1, 1);
240      for (size_t ix=0; ix < _h_plus_lam->numBins(); ++ix) {
241       	normalize(_h_plus_lam->bin(ix+1));
242       	normalize(_h_minus_lam->bin(ix+1));
243       	Estimate1DPtr eTemp;
244        book(eTemp, "/TMP/a_lam_" + to_string(ix), 20, -1.0, 1.0);
245       	asymm(_h_plus_lam->bin(ix+1), _h_minus_lam->bin(ix+1), eTemp);
246       	pair<double,double> alpha = calcAsymmetry(eTemp, 1);
247       	h_asym->bin(ix+1).set(-alpha.first, alpha.second);
248      }
249      normalize(_h_plus_lam_large1 );
250      normalize(_h_minus_lam_large1);
251      Estimate1DPtr eTemp;
252      book(eTemp, "/TMP/a_lam_large1", 20, -1.0, 1.0);
253      asymm(_h_plus_lam_large1,_h_minus_lam_large1,eTemp);
254      alpha = calcAsymmetry(eTemp,1);
255      book(h_asym,3,1,2);
256      h_asym->bin(1).set(-alpha.first, alpha.second);
257      normalize(_h_plus_lam_large2 );
258      normalize(_h_minus_lam_large2);
259      book(eTemp, "/TMP/a_lam_large2", 20, -1.0, 1.0);
260      asymm(_h_plus_lam_large2,_h_minus_lam_large2, eTemp);
261      alpha = calcAsymmetry(eTemp,1);
262      book(h_asym,3,1,3);
263      h_asym->bin(1).set(-alpha.first, alpha.second);
264    }
265
266    /// @}
267
268
269    /// @name Histograms
270    /// @{
271    Histo1DGroupPtr _h_ctheta,_h_cphi,_h_plus_lam,_h_minus_lam;
272    Histo1DPtr _h_ctheta_large;
273    Histo1DPtr _h_cphi_low, _h_cphi_mid, _h_cphi_high;
274    Histo1DPtr _h_plus_lam_large1,_h_plus_lam_large2;
275    Histo1DPtr _h_minus_lam_large1,_h_minus_lam_large2;
276    /// @}
277
278  };
279
280
281  RIVET_DECLARE_PLUGIN(OPAL_1997_I447188);
282
283
284}