PNNFSI.cc

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//
// NN FSI from the Jost function
//
//                                  Author:  I. Froehlich
 
 
using namespace std;
#include <sstream>
#include <iostream>
#include <iomanip>
 
#include "PNNFSI.h"
#include "PDynamicData.h"
 
 
ClassImp(PNNFSI)
 
PNNFSI::PNNFSI() {
    Setup();
};
 
PNNFSI::PNNFSI(const Char_t *id, const  Char_t *de, Int_t key) :
    PChannelModel(id, de, key) {
 
    Setup();
 
};
 
void PNNFSI::Setup(void) {
    n1 = n2 = NULL;
    daughter_pos = 0;
    for (int i=0; i<NNFSI_MAX_DAUGHTERS; i++) {
    daughters[i] = NULL;
    }
 
    triplet = 0;
    a0 = -23.768;
    r0 = 2.75;
    is_np = 0;
}
 
PDistribution *PNNFSI::Clone(const char *) const {
    return new PNNFSI((const PNNFSI &)* this);
};
 
 
Bool_t PNNFSI::Init(void) {
 
    //looking for 2 nucleons. This is mandatory
    n1 = GetParticle("p");
    n2 = GetParticle("p");
    if (!n2) {
    n2 = GetParticle("n");
    is_np =1;
    }
 
    if (!n1 || !n2) {
    Warning("Init", "No 2 nucleons");
    return kFALSE;
    }
 
    //Now get all daugthers
    for (int i=0; i<NNFSI_MAX_DAUGHTERS; i++) {
    daughters[i]= GetParticle("daughter");
    if (daughters[i]) {
        daughter_pos++;
    }
    }
 
    return kTRUE;
};
 
Double_t PNNFSI::GetWeight(Double_t *mass, Int_t *) {
    TComplex jost(1.,0.);
    Double_t k = mass[0]/0.197;
    Double_t alpha = 1./r0 * (
    sqrt (1.-2.*r0/a0) +1.
    );
    Double_t beta = 1./r0 * (
    sqrt (1.-2.*r0/a0) -1.
    );
    if (!triplet) {
    TComplex num(k,beta);
    TComplex denom(k,alpha);
    jost = num/denom;
    } else {
    cout << "TODO" << endl;
    }
 
//    if (!is_np)
    return (1./jost.Rho2());
 
}
 
Double_t PNNFSI::GetWeight(void) {
//     n1->Print();
//     n2->Print();
 
    TLorentzVector a = ((TLorentzVector) *n1) + ((TLorentzVector) *n2);
    TLorentzVector b = ((TLorentzVector) *n1);
 
    b.Boost(-a.BoostVector());
 
    Double_t k = b.P();
    weight = GetWeight(&k);
 
    return weight;
}
 
 
 
ClassImp(PNNFSI)