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Bertram Kopf authored44edc3a1
Utils.cc 16.37 KiB
#include "qft++/relativistic-quantum-mechanics/Utils.hh"
#include "qft++/relativistic-quantum-mechanics/BlattWeisskopf.hh"
/* Copyright 2008 Mike Williams (mwill@jlab.org)
*
* This file is part of qft++.
*
* qft++ 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.
*
* qft++ 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 qft++. If not, see <http://www.gnu.org/licenses/>.
*/
//_____________________________________________________________________________
/** @file Utils.C
* @brief Utility function source file
*/
//_____________________________________________________________________________
/// Utility function used by Clebsch
inline double dfact(double __x){
if((__x < 0.00001) && (__x >= 0.0)) return 1.;
if(__x < 0) return 0.;
return __x*dfact(__x - 1.);
}
//_____________________________________________________________________________
/// Returns i!
inline int factorial(int __i) {
if (__i<0){
cerr << endl;
cerr << "factoral value " << __i << " must be >=0 !!! "
<< endl;
exit(1);
}
int f = 1;
if((__i == 0) || (__i == 1)) f = 1;
else{
while(__i > 0){
f = f*__i;
__i--;
}
}
return f;
}
//_____________________________________________________________________________
// define a few macros
#define MAX(x,y) (x>y ? x : y)
#define MIN(x,y) (x<y ? x : y)
//_____________________________________________________________________________
vector<LS> GetValidLS(const Spin &__j,int __parity,const Spin &__s1,int __p1,
const Spin &__s2,int __p2){
vector<LS> valid_ls;
LS ls;
for(Spin S = abs(__s1 - __s2); S <= (__s1 + __s2); S++){
for(int L = (int)abs(__j - S); L <= (int)(__j + S); L++){
// check the parity
if(abs(__p1*__p2*pow(-1.,L) - __parity) < 1.e-5) {
ls.L = L;
ls.S = S;
valid_ls.push_back(ls); }
}
}
return valid_ls;
}
//_____________________________________________________________________________
double Gamma(double __z){
float x = abs(__z);
// Coefficients for the series expansion
double c[7] = { 2.5066282746310005, 76.18009172947146, -86.50532032941677
,24.01409824083091, -1.231739572450155, 0.1208650973866179e-2
,-0.5395239384953e-5};
double y = x;
double tmp = x + 5.5;
tmp = (x+0.5)*log(tmp)-tmp;
double ser = 1.000000000190015;
for(int i = 1; i < 7; i++) {
y += 1;
ser += c[i]/y;
}
double lnGamma = tmp+log(c[0]*ser/x); // natural log of Gamma(z)
if(__z > 0) return exp(lnGamma);
else if(__z == 0.) return 0.;
else {
double pi = 3.1415926535;
return (-1.*pi)/(exp(lnGamma)*sin(pi*x)*x);
}
}
//_____________________________________________________________________________
double Clebsch(const Spin &__j1,const Spin &__m1,const Spin &__j2,
const Spin &__m2,const Spin &__J,const Spin &__M){
if((__m1 + __m2) != __M) return 0.;
if(abs(__m1) > __j1) return 0;
if(abs(__m2) > __j2) return 0;
// convert to pure integers (each 2*spin)
int j1 = (int)(2.*__j1);
int m1 = (int)(2.*__m1);
int j2 = (int)(2.*__j2);
int m2 = (int)(2.*__m2);
int J = (int)(2.*__J);
int M = (int)(2.*__M);
double n0,n1,n2,n3,n4,n5,d0,d1,d2,d3,d4,A,exp;
int nu = 0;
double sum = 0;
while(((d3=(j1-j2-M)/2+nu) < 0)||((n2=(j1-m1)/2+nu) < 0 )) { nu++;}
while (((d1=(J-j1+j2)/2-nu) >= 0) && ((d2=(J+M)/2-nu) >= 0)
&&((n1=(j2+J+m1)/2-nu) >= 0 )){
d3=((j1-j2-M)/2+nu);
n2=((j1-m1)/2+nu);
d0=dfact((double) nu);
exp=nu+(j2+m2)/2;
n0 = (double) pow(-1.,exp);
sum += ((n0*dfact(n1)*dfact(n2))/(d0*dfact(d1)*dfact(d2)*dfact(d3)));
nu++;
}
if (sum == 0) return 0;
n0 = J+1;
n1 = dfact((double) (J+j1-j2)/2);
n2 = dfact((double) (J-j1+j2)/2);
n3 = dfact((double) (j1+j2-J)/2); n4 = dfact((double) (J+M)/2);
n5 = dfact((J-M)/2);
d0 = dfact((double) (j1+j2+J)/2+1);
d1 = dfact((double) (j1-m1)/2);
d2 = dfact((double) (j1+m1)/2);
d3 = dfact((double) (j2-m2)/2);
d4 = dfact((double) (j2+m2)/2);
A = ((double) (n0*n1*n2*n3*n4*n5))/((double) (d0*d1*d2*d3*d4));
return sqrt(A)*sum;
}
//_____________________________________________________________________________
double Wigner_d(const Spin &__j,const Spin &__m,const Spin &__n,double __beta){
int J = (int)(2.*__j);
int M = (int)(2.*__m);
int N = (int)(2.*__n);
int temp_M, k, k_low, k_hi;
double const_term = 0.0, sum_term = 0.0, d = 1.0;
int m_p_n, j_p_m, j_p_n, j_m_m, j_m_n;
int kmn1, kmn2, jmnk, jmk, jnk;
double kk;
if (J < 0 || abs (M) > J || abs (N) > J) {
cerr << endl;
cerr << "d: you have entered an illegal number for J, M, N." << endl;
cerr << "Must follow these rules: J >= 0, abs(M) <= J, and abs(N) <= J."
<< endl;
cerr << "J = " << J << " M = " << M << " N = " << N << endl;
return 0.;
}
if (__beta < 0) {
__beta = fabs (__beta);
temp_M = M;
M = N;
N = temp_M;
}
m_p_n = (M + N) / 2;
j_p_m = (J + M) / 2;
j_m_m = (J - M) / 2;
j_p_n = (J + N) / 2;
j_m_n = (J - N) / 2;
kk = (double)factorial(j_p_m)*(double)factorial(j_m_m)
*(double)factorial(j_p_n) * (double)factorial(j_m_n) ;
const_term = pow((-1.0),(j_p_m)) * sqrt(kk);
k_low = MAX(0, m_p_n);
k_hi = MIN(j_p_m, j_p_n);
for (k = k_low; k <= k_hi; k++) {
kmn1 = 2 * k - (M + N) / 2;
jmnk = J + (M + N) / 2 - 2 * k;
jmk = (J + M) / 2 - k;
jnk = (J + N) / 2 - k;
kmn2 = k - (M + N) / 2;
sum_term += pow ((-1.0), (k)) *
((pow (cos (__beta / 2.0), kmn1)) * (pow (sin (__beta / 2.0), jmnk))) /
(factorial (k) * factorial (jmk) * factorial (jnk) * factorial (kmn2));
}
d = const_term * sum_term;
return d;
}
// double Wigner_d_new(const Spin &__j,const Spin &__m,const Spin &__n,double __beta){
// int J = (int)(2.*__j);
// int M = (int)(2.*__m);
// int N = (int)(2.*__n);
// int temp_M, k, k_low, k_hi;
// double const_term = 0.0, sum_term = 0.0, d = 1.0;
// int m_p_n, j_p_m, j_p_n, j_m_m, j_m_n, m_n_n;
// int kmn2, jmnk, jmk, jnk;
// double kk;
// if (J < 0 || abs (M) > J || abs (N) > J) {
// cerr << endl;
// cerr << "d: you have entered an illegal number for J, M, N." << endl;
// cerr << "Must follow these rules: J >= 0, abs(M) <= J, and abs(N) <= J."
// << endl;
// cerr << "J = " << J << " M = " << M << " N = " << N << endl;
// return 0.;
// }
// double preFactor=1.;
// if (M<0 && N<0){
// preFactor=pow(-1.,M-N);
// M=-M;
// N=-N;
// }
// if (M < N){
// __beta = -__beta;
// temp_M = M;
// M = N;
// N = temp_M;
// }
// m_p_n = (M + N) / 2;
// j_p_m = (J + M) / 2;
// j_m_m = (J - M) / 2;
// j_p_n = (J + N) / 2;
// j_m_n = (J - N) / 2;
// m_n_n = (M - N) / 2;
// kk = (double)factorial(j_p_m)*(double)factorial(j_m_m)
// *(double)factorial(j_p_n) * (double)factorial(j_m_n) ;
// // const_term = pow((-1.0),(m_n_n)) * sqrt(kk);
// const_term = sqrt(kk);
// // k_low = MAX(0, 0);
// k_low = 0;
// k_hi = MIN(j_p_n, j_m_m);
// for (k = k_low; k <= k_hi; k++) {
// // kmn1 = 2 * k - (M - N) / 2;
// jmnk = J + (N - M) / 2 - 2 * k;
// jmk = (J - M) / 2 - k;
// jnk = (J + N) / 2 - k;// kmn2 = k + (M - N) / 2;
// int mmn2k=(M - N)/2 + 2 * k;
// // std::cout << "kmn1=\t" << kmn1 <<"\n"
// // << "jmnk=\t" << jmnk <<"\n"
// // << "jmk=\t" << jmk <<"\n"
// // << "jnk=\t" << jnk <<"\n"
// // << "kmn2=\t" << kmn2 <<"\n"
// // << "mmn2k=\t" << mmn2k <<"\n"
// // << std::endl;
// sum_term += pow ((-1.0), (k)) *
// ((pow (cos (__beta / 2.0), jmnk)) * (pow (sin (__beta / 2.0), mmn2k))) /
// (factorial (k) * factorial (jmk) * factorial (jnk) * factorial (kmn2));
// }
// d = preFactor*const_term * sum_term;
// return d;
// }
//_____________________________________________________________________________
complex<double> BreitWigner(const Vector4<double> &__p4,double __mass,
double __width){
complex<double> i(0.,1.);
return __mass*__width/(__mass*__mass - __p4*__p4- i*__mass*__width);
}
//
complex<double> BreitWignerBlattW(const Vector4<double> &__p4, double __massA,
double __massB, double __mass0, double __width, int __LL){
if( (__massA < 0.) || (__massB < 0.) || __mass0<0.) {
std::cout << "Invalid mass values " << __massA << "\t" << __massB << "\t" << __mass0 <<std::endl;
assert(0);
}
if (__LL==0) return BreitWigner(__p4,__mass0,__width);
complex<double> i(0.,1.);
double massAB=__p4.Mass();
if ( (__massA+__massB) > __mass0) return BreitWigner(__p4,__mass0,__width);
if ( (__massA+__massB) > massAB) return BreitWigner(__p4,__mass0,__width);
// break up momentum q0
double q0=sqrt( (__mass0*__mass0-(__massA+__massB)*(__massA+__massB))
* (__mass0*__mass0-(__massA-__massB)*(__massA-__massB)) )
/(2*__mass0);
// break up momentum qab
double qab=sqrt( (massAB*massAB-(__massA+__massB)*(__massA+__massB))
* (massAB*massAB-(__massA-__massB)*(__massA-__massB)) )
/(2*massAB);
// phase space factor rhoM0
double rhoM0=2*q0/__mass0;
// phase space factor rhoMab
double rhoMab=2*qab/massAB;
// R=1.5 GeV-1 for intermediate resonances
BlattWeisskopf blattWk(__LL, 1.5, q0);
double blattWqq0=blattWk(qab);
complex<double> result=__mass0*__width*blattWqq0/
(__mass0*__mass0 - massAB*massAB - i*(__mass0*__width* blattWqq0* blattWqq0* rhoMab/rhoM0));
return result;
}
//
complex<double> FlatteA980(const Vector4<double> &__p4, double __mass0, double g_KK, double g_EtaPi){
complex<double> i(0.,1.);
const double mPipm=0.13957018;
const double mEta=0.547853;
const double mKpm=0.493677;
const double mK0=0.497614;
double mAB=__p4.Mass();
if( (mAB < 1e-8)){
std::cout << "Invalid KK mass " << mAB << " < 1e-8" <<std::endl;
assert(0);
}
//calculate phase-space factors
double mPiMmEtaSqr=((mPipm-mEta)/mAB)*((mPipm-mEta)/mAB);
if (mPiMmEtaSqr>1.) mPiMmEtaSqr=1.;
double mPiMpEtaSqr=((mPipm+mEta)/mAB)*((mPipm+mEta)/mAB);
if (mPiMpEtaSqr>1.) mPiMpEtaSqr=1.;
double mKpmmK0Sqr=((mKpm-mK0)/mAB)*((mKpm-mK0)/mAB);
if (mKpmmK0Sqr>1.) mKpmmK0Sqr=1.;
double mKpmpK0Sqr=((mKpm+mK0)/mAB)*((mKpm+mK0)/mAB);
if (mKpmpK0Sqr>1.) mKpmpK0Sqr=1.;
double rho1=sqrt( (1-mPiMmEtaSqr)* (1-mPiMpEtaSqr) );
double rho2=sqrt( (1-mKpmmK0Sqr)* (1-mKpmpK0Sqr) );
complex<double> result=g_KK*g_KK/( __mass0*__mass0 - mAB*mAB - i * (rho1*g_EtaPi*g_EtaPi+rho2*g_KK*g_KK) );
return result;
}
complex<double> Flatte(const Vector4<double> &__p4, std::pair<const double, const double>& decPair1, std::pair<const double
, const double>& decPair2, double __mass0, double g1, double g2){
complex<double> i(0.,1.);
const double m1a=decPair1.first;
const double m1b=decPair1.second;
const double m2a=decPair2.first;
const double m2b=decPair2.second;
double mAB=__p4.Mass();
//calculate gammas with phase-space factors
complex<double> gamma11=g1*breakupMomQ(mAB, m1a, m1b);
complex<double> gamma22=g2*breakupMomQ(mAB, m2a, m2b);
// double ph1Sqr=mAB*mAB/4-m1a*m1b;
// complex<double> gamma11(0.,0.);
// if (ph1Sqr>=0.) gamma11=complex<double>( g1*sqrt(ph1Sqr), 0.);
// else gamma11=complex<double>(0., g1*sqrt(-ph1Sqr));
// double ph2Sqr=mAB*mAB/4-m2a*m2b;
// complex<double> gamma22(0.,0.);
// if (ph2Sqr>=0.) gamma22=complex<double>(g2*sqrt(ph2Sqr), 0.);
// else gamma22=complex<double>(0., g2*sqrt(-ph2Sqr));
complex<double> gammaLow(0.,0.);
if( (m1a+m1b) < (m2a+m2b) ) gammaLow=gamma11;
else gammaLow=gamma22;
complex<double> result=__mass0*sqrt(gammaLow*gamma11)/( __mass0*__mass0 - mAB*mAB - i * __mass0 * (gamma11+gamma22) );
return result;
}
//_____________________________________________________________________________
complex<double> ReggePropagator(double __t,double __s,double __a,double __b,
const Spin &__spin,int __sig,int __exp_fact){
complex<double> prop,numerator,denominator;
double alpha = __a*__t + __b; // trajectory
double pi = 3.1415926535;
complex<double> i(0.,1.);
numerator = pow(__s,alpha - __spin)*pi*__a;
numerator *= ((double)__sig + ((double)__exp_fact)*exp(-i*pi*alpha));
double gamma_arg = alpha + 1. - __spin;
if(gamma_arg < 0.) denominator = 2*pi/(abs(gamma_arg)*Gamma(abs(gamma_arg)));
else if(gamma_arg == 0.) denominator = 2*pi;
else denominator = 2*sin(pi*gamma_arg)*Gamma(gamma_arg);
prop = numerator/denominator;
return prop;
}
//_____________________________________________________________________________
Spin GetSpin(const string &__spin){
Spin j;
string::size_type div_pos = __spin.find("/");
if(div_pos != string::npos){
string tmp;
tmp.assign(__spin,0,div_pos);
double numer = atof(tmp.c_str());
tmp.assign(__spin,div_pos + 1,__spin.size() - div_pos - 1);
double denom = atof(tmp.c_str());
j = numer/denom;
}
else j = atof(__spin.c_str());
return j;
}
//_____________________________________________________________________________
void Wigner_d(const Spin &__jmax,double __beta,
map<Spin,map<Spin,map<Spin,double> > > &__d){
__d.clear();
Spin jmin,one_half = 1/2.;
if(__jmax == 0.){
__d[0][0][0] = 1.;
return;
}
double cb = cos(__beta);
double sb = sin(__beta);
// j=1 d's
map<Spin,map<Spin,double> > d1;
d1[1][1] = (1+cb)/2.;
d1[1][0] = -sb/sqrt(2.);
d1[1][-1] = (1-cb)/2.;
d1[0][1] = sb/sqrt(2.); d1[0][0] = cb;
d1[0][-1] = -sb/sqrt(2.);
d1[-1][1] = (1-cb)/2.;
d1[-1][0] = sb/sqrt(2.);
d1[-1][-1] = (1+cb)/2.;
if(__jmax.Denominator() == 1){ // integral spins
__d[0][0][0] = 1.0;
if(__jmax == 0.) return;
__d[1][1][1] = d1[1][1];
__d[1][1][0] = d1[1][0];
__d[1][1][-1] = d1[1][-1];
__d[1][0][1] = d1[0][1];
__d[1][0][0] = d1[0][0];
__d[1][0][-1] = d1[0][-1];
__d[1][-1][1] = d1[-1][1];
__d[1][-1][0] = d1[-1][0];
__d[1][-1][-1] = d1[-1][-1];
if(__jmax == 1.) return;
jmin = 2.;
}
else { // half-integral spins
__d[one_half][one_half][one_half] = cos(__beta/2.);
__d[one_half][one_half][-one_half] = -sin(__beta/2.);
__d[one_half][-one_half][one_half] = sin(__beta/2.);
__d[one_half][-one_half][-one_half] = cos(__beta/2.);
if(__jmax == one_half) return;
jmin = 3/2.;
}
for(Spin j = jmin; j <= __jmax; j++){
for(Spin m = -j; m <= j; m++){
for(Spin n = -j; n <= j; n++){
double djmn = 0.;
for(Spin mm = -1; mm <= 1; mm++){
for(Spin nn = -1; nn <= 1; nn++){
djmn += Clebsch(j-1,m-mm,1,mm,j,m)*Clebsch(j-1,n-nn,1,nn,j,n)
*__d[j-1][m-mm][n-nn]*d1[mm][nn];
}
}
__d[j][m][n] = djmn;
}
}
}
}
//_____________________________________________________________________________
void Wigner_D(const Spin &__jmax,double __alpha,double __beta,double __gamma,
map<Spin,map<Spin,map<Spin,complex<double> > > > &__D){
complex<double> i(0.,1.);
map<Spin,map<Spin,map<Spin,double> > > d;
Wigner_d(__jmax,__beta,d);
Spin jmin;
if(d.find(0) != d.end()) jmin = 0;
else jmin = 1/2.;
for(Spin j = jmin; j <= __jmax; j++){
for(Spin m = -j; m <= j; m++){
for(Spin n = -j; n <= j; n++)
__D[j][m][n] = exp(-i*(m*__alpha + n*__gamma))*d[j][m][n];
}
}
}
//_____________________________________________________________________________
complex<double> phaseSpaceFac(double mass, double massDec1, double massDec2){
complex<double> result(0.,0.);
if(mass < 1e-8) {
std::cout << "mass " << mass << " very close to 0 or negative; not possible to calculate phasespace factor " <<std::endl;
assert(0);
}
double termPlus=(massDec1+massDec2)/mass;
double termMinus=(massDec1-massDec2)/mass;
double tmpVal=(1.-termPlus*termPlus) * (1.-termMinus*termMinus);
// double tmpVal=mass*mass/4-massDec1*massDec2;
if (tmpVal>=0.) result = complex<double> (sqrt(tmpVal), 0. );
else result = complex<double> (0., sqrt(-tmpVal));
return result;
}
complex<double> breakupMomQ(double mass, double massDec1, double massDec2){
complex<double> result=phaseSpaceFac(mass, massDec1, massDec2)*mass/2.;
return result;
}