added barrier factor class

PwaUtils/BarrierFactor.cc

+//************************************************************************//
+//                                                                        //
+//  Copyright 2014 Bertram Kopf (bertram@ep1.rub.de)                      //
+//                 Julian Pychy (julian@ep1.rub.de)                       //
+//                 - Ruhr-Universität Bochum                              //
+//                                                                        //
+//  This file is part of Pawian.                                          //
+//                                                                        //
+//  Pawian is free software: you can redistribute it and/or modify        //
+//  it under the terms of the GNU General Public License as published by  //
+//  the Free Software Foundation, either version 3 of the License, or     //
+//  (at your option) any later version.                                   //
+//                                                                        //
+//  Pawian is distributed in the hope that it will be useful,             //
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of        //
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         //
+//  GNU General Public License for more details.                          //
+//                                                                        //
+//  You should have received a copy of the GNU General Public License     //
+//  along with Pawian.  If not, see <http://www.gnu.org/licenses/>.       //
+//                                                                        //
+//************************************************************************//
+
+#include <cmath>
+#include "PwaUtils/BarrierFactor.hh"
+#include "ErrLogger/ErrLogger.hh"
+
+const double BarrierFactor::qRDefault = 0.1973; // GeV
+
+BarrierFactor::BarrierFactor(double l, double q0, double qR) :
+   _l(l),
+   _qR(qR),
+   _q0(q0)
+{
+
+   if(q0 < 0){
+      Alert << "q0 < 0" << endmsg;
+   }
+
+   _B0 = BlattWeisskopf(_q0);
+
+   if(_B0 < 0){
+      Alert << "_B0 < 0" << endmsg;
+   }
+}
+
+
+
+double BarrierFactor::BlattWeisskopf(double q){
+   return BlattWeisskopf(_l, q*q/_qR/_qR);
+}
+
+
+
+double BarrierFactor::BlattWeisskopf(int l, double q, double qR){
+   return BlattWeisskopf(l, q*q/qR/qR);
+}
+
+
+
+double BarrierFactor::BlattWeisskopf(int l, double z){
+
+   if(z<0){
+      Alert << "z<0" << endmsg;
+      return 0;
+   }
+
+   if(0==l){
+      return 1.0;
+   }
+   else if(1==l){
+      return std::sqrt(2.*z / (z+1.));
+   }
+   else if(2==l){
+      return sqrt(13.*z*z / (z*z + 3.*z + 9.));
+   }
+   else if(3==l){
+      return sqrt(277.*z*z*z / (z*z*z + 6.*z*z + 45.*z + 225.));
+   }
+   else if(4==l){
+      return sqrt(12746.*z*z*z*z / 
+		  (z*z*z*z + 10.*z*z*z + 135.*z*z + 1575.*z + 11025.));
+   }
+   else if(5==l){
+      return sqrt(998881.*z*z*z*z*z / 
+		  (z*z*z*z*z + 15.*z*z*z*z + 315.*z*z*z + 
+		   6300.*z*z + 99225.*z + 893025.));
+   }
+   else if(6==l){
+      return sqrt(118394977.*z*z*z*z*z*z / 
+		  (z*z*z*z*z*z + 21.*z*z*z*z*z + 630.*z*z*z*z + 18900.*z*z*z +
+		   496125.*z*z + 9823275.*z + 108056025.));
+   }
+   else{
+      Alert << "Cannot compute BlattWeisskopf factor for l=" << l << endmsg;
+   }
+   return 0;
+}
+
+
+
+double BarrierFactor::D(double q){
+   return BlattWeisskopf(q) / _B0;
+}
+
+
+
+double BarrierFactor::D(int l, double q, double q0, double qR){
+   return BlattWeisskopf(l, q, qR) / BlattWeisskopf(l, q0, qR);
+}

PwaUtils/BarrierFactor.hh

+//************************************************************************//
+//                                                                        //
+//  Copyright 2014 Bertram Kopf (bertram@ep1.rub.de)                      //
+//                 Julian Pychy (julian@ep1.rub.de)                       //
+//                 - Ruhr-Universität Bochum                              //
+//                                                                        //
+//  This file is part of Pawian.                                          //
+//                                                                        //
+//  Pawian is free software: you can redistribute it and/or modify        //
+//  it under the terms of the GNU General Public License as published by  //
+//  the Free Software Foundation, either version 3 of the License, or     //
+//  (at your option) any later version.                                   //
+//                                                                        //
+//  Pawian is distributed in the hope that it will be useful,             //
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of        //
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         //
+//  GNU General Public License for more details.                          //
+//                                                                        //
+//  You should have received a copy of the GNU General Public License     //
+//  along with Pawian.  If not, see <http://www.gnu.org/licenses/>.       //
+//                                                                        //
+//************************************************************************//
+
+#pragma once
+
+
+class BarrierFactor
+{
+
+public:
+   BarrierFactor(double l, double q0, double qR);
+   double D(double q);
+   double BlattWeisskopf(double q);
+   static double D(int l, double q, double q0, double qR);
+   static double BlattWeisskopf(int l, double q, double qR);
+   static double BlattWeisskopf(int l, double z);
+
+   static const double qRDefault;
+
+private:
+   double _l;
+   double _qR;
+   double _q0;
+   double _B0;
+ };