BOSS_7.0.2: /home/bes3soft/bes3soft/Boss/7.0.2/dist/7.0.2/Generator/BesEvtGen/BesEvtGen-00-03-58/src/EvtGen/EvtGenModels/EvtHQET2FF.cc Source File

00001 //--------------------------------------------------------------------------
00002 //
00003 // Module: EvtHQET2FF.cc
00004 //
00005 // Description: form factors for B->D*lnu & B->Dlnu according to HQET 
00006 //              with dispersive FF
00007 //
00008 // Modification history:
00009 //
00010 //    Marco Bomben     March 10, 2003        Module created
00011 //
00012 //------------------------------------------------------------------------
00013 // 
00014 #include "EvtGenBase/EvtPatches.hh"
00015 #include "EvtGenBase/EvtPatches.hh"
00016 #include "EvtGenBase/EvtReport.hh"
00017 #include "EvtGenModels/EvtHQET2FF.hh"
00018 #include "EvtGenBase/EvtId.hh"
00019 #include <string>
00020 #include "EvtGenBase/EvtPDL.hh"
00021 #include <math.h>
00022 
00023 
00024 
00025 EvtHQET2FF::EvtHQET2FF(double hqetrho2, double hqetha1_1 , double hqetr1_1, double hqetr2_1) {
00026 
00027   rho2 = hqetrho2;
00028   r1_1 = hqetr1_1;
00029   r2_1 = hqetr2_1;
00030   ha1_1 = hqetha1_1;
00031 
00032   return;
00033 }
00034 
00035 EvtHQET2FF::EvtHQET2FF(double hqetrho2, double hqetv1_1) {
00036 
00037   rho2 = hqetrho2;
00038   v1_1 = hqetv1_1;
00039 
00040   return;
00041 }
00042 
00043 
00044 void EvtHQET2FF::getscalarff(EvtId parent,EvtId daught,
00045                             double t, double mass, double *f0p, double *f0m) {
00046 
00047 
00048   double mb=EvtPDL::getMeanMass(parent);
00049   double w = ((mb*mb)+(mass*mass)-t)/(2.0*mb*mass);
00050 
00051 // Form factors have a general form, with parameters passed in
00052 // from the arguements.
00053 
00054   // Use disparsion relation parametrization from 
00055   // I.Caprini, L.Lelluch, M.Neubert, Nucl. Phys. B 530,153(1998)
00056   const double z = (sqrt(w+1)-sqrt(2.))/(sqrt(w+1)+sqrt(2.));
00057   double v1 = v1_1*(1.- 8.*rho2*z + (51.*rho2-10.)*z*z - (252.*rho2-84.)*z*z*z)
00058 ;
00059 
00060   *f0p=v1;
00061   *f0m = 0.0;
00062 
00063   return;
00064  }
00065 
00066 void EvtHQET2FF::getvectorff(EvtId parent,EvtId daught,
00067                             double t, double mass, double *a1f,
00068                             double *a2f, double *vf, double *a0f ){
00069 
00070 
00071   double mb=EvtPDL::getMeanMass(parent);
00072   double w = ((mb*mb)+(mass*mass)-t)/(2.0*mb*mass);
00073 
00074 // Form factors have a general form, with parameters passed in
00075 // from the arguements.
00076 
00077   double rstar = ( 2.0*sqrt(mb*mass))/(mb+mass);
00078 
00079   // Use disparsion relation parametrization from 
00080   // I.Caprini, L.Lelluch, M.Neubert, Nucl. Phys. B 530,153(1998)
00081   const double z = (sqrt(w+1)-sqrt(2.))/(sqrt(w+1)+sqrt(2.));
00082   double ha1 =ha1_1*(1.- 8.*rho2*z + (53.*rho2-15.)*z*z - (231.*rho2-91.)*z*z*z);
00083   double r1 = r1_1-0.12*(w-1)+0.05*(w-1)*(w-1);
00084   double r2 = r2_1+0.11*(w-1)-0.06*(w-1)*(w-1);
00085 ;
00086 
00087   *a1f = (1.0 - (t/((mb+mass)*(mb+mass))))*ha1;
00088   *a1f = (*a1f)/rstar;
00089   *a2f = (r2/rstar)*ha1;
00090   *vf = (r1/rstar)*ha1;
00091   *a0f = 0.0;
00092 
00093   return;
00094  }
00095