Page MenuHomeHEPForge
Files F7877973

No OneTemporary
Actions

View Options

diff --git a/Models/StandardModel/O2AlphaS.cc b/Models/StandardModel/O2AlphaS.cc
--- a/Models/StandardModel/O2AlphaS.cc
+++ b/Models/StandardModel/O2AlphaS.cc
@@ -1,170 +1,170 @@
// -*- C++ -*-
//
// O2AlphaS.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2011 The Herwig Collaboration
//
// Herwig is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
//
// This is the implementation of the non-inlined, non-templated member
// functions of the O2AlphaS class.
//
#include "O2AlphaS.h"
#include "ThePEG/StandardModel/StandardModelBase.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ThePEG/PDT/ParticleData.h"
#include "ThePEG/Interface/Parameter.h"
#include "ThePEG/Interface/Switch.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
using namespace Herwig;
void O2AlphaS::persistentOutput(PersistentOStream & os) const {
os << ounit(_lambdaQCD,GeV) << _bcoeff << _ccoeff << ounit(_lambdas,GeV)
<< ounit(_threshold,GeV) << _match << _copt;
}
void O2AlphaS::persistentInput(PersistentIStream & is, int) {
is >> iunit(_lambdaQCD,GeV) >> _bcoeff >> _ccoeff >> iunit(_lambdas,GeV)
>> iunit(_threshold,GeV) >> _match >> _copt;
}
ClassDescription<O2AlphaS> O2AlphaS::initO2AlphaS;
// Definition of the static class description member.
void O2AlphaS::Init() {
static ClassDocumentation<O2AlphaS> documentation
("The O2AlphaS class implements the next-to-leading order alphaS in the same"
" way as in FORTRAN HERWIG");
static Parameter<O2AlphaS,Energy> interfaceLambdaQCD
("LambdaQCD",
"The value of Lambda QCD",
&O2AlphaS::_lambdaQCD, MeV, 180.*MeV, 50.*MeV, 500.0*MeV,
false, false, Interface::limited);
static Switch<O2AlphaS,unsigned int> interfaceLambdaType
("LambdaType",
"Which type of Lambda to use",
&O2AlphaS::_copt, 0, false, false);
static SwitchOption interfaceLambdaTypeMonteCarlo
(interfaceLambdaType,
"MonteCarlo",
"Use a Monte Carlo scheme as in the FORTRAN program",
0);
static SwitchOption interfaceLambdaTypeMSBar
(interfaceLambdaType,
"MSBar",
"Use the MSBar scheme",
1);
}
vector<Energy2> O2AlphaS::flavourThresholds() const {
vector<Energy2> thresholds(_threshold.size());
transform(_threshold.begin(), _threshold.end(),
thresholds.begin(),
sqr<Energy>);
return thresholds;
}
void O2AlphaS::doinit() {
// thresholds
for ( int ix=1; ix<7; ++ix ) {
if ( quarkMasses().empty() ) {
tPDPtr p = getParticleData(ix);
_threshold[ix-1] = p->mass();
} else
_threshold[ix-1] = quarkMasses()[ix-1];
}
// d is heavier than u, need to swap
swap(_threshold[0],_threshold[1]);
// beta function coefficients
const double ca = generator()->standardModel()->Nc();
const double cf = (sqr(ca)-1.)/2./ca;
for(unsigned int ix=3;ix<7;++ix)
{
_bcoeff[ix-1]=(11.*ca-2.*ix)/(12.*Constants::pi);
_ccoeff[ix-1]=(17.*sqr(ca)-ix*(5.*ca+3.*cf))/(24.*sqr(Constants::pi))/sqr(_bcoeff[ix-1]);
}
if(_copt==0)
{
double kfac(ca*(67./18.-sqr(Constants::pi)/6.)-25./9.);
_lambdas[5]=_lambdaQCD*exp(kfac/(4.*Constants::pi*_bcoeff[4]))/sqrt(2.);
}
else{_lambdas[5]=_lambdaQCD;}
// calculate the threshold matching
double rho=2.*log(_threshold[5]/_lambdas[5]);
double rat=log(rho)/rho;
_match[5]=(_bcoeff[4]/(1.-_ccoeff[4]*rat)-_bcoeff[5]/(1.-_ccoeff[5]*rat))*rho;
rho=2.*log(_threshold[4]/_lambdas[5]);
rat=log(rho)/rho;
_match[4]=(_bcoeff[4]/(1.-_ccoeff[4]*rat)-_bcoeff[3]/(1.-_ccoeff[3]*rat))*rho;
rho=2.*log(_threshold[3]/_lambdas[5]);
rat=log(rho)/rho;
_match[3]=(_bcoeff[3]/(1.-_ccoeff[3]*rat)-_bcoeff[2]/(1.-_ccoeff[2]*rat))*rho
+_match[4];
// calculate the 4-flavour lambda
_lambdas[4]=_lambdas[5]*pow(_threshold[4]/_lambdas[5],2./25.)*
pow(2.*log(_threshold[4]/_lambdas[5]),963./14375.);
// calculate the 3-flavour lambda
double eps(1.e-6),d35(-1./(_bcoeff[2]*_match[3])),rlf,drh;
unsigned int ix=0;
do
{
rat=log(d35)/d35;
rlf=_bcoeff[2]*d35/(1.-_ccoeff[2]*rat);
drh=_bcoeff[2]*(rlf+_match[3])*sqr(d35)/
((1.-2.*_ccoeff[2]*rat+_ccoeff[2]/d35)*sqr(rlf));
d35=d35-drh;
++ix;
}
while(ix<100&&abs(drh)>eps*d35);
_lambdas[3]=_lambdas[5]*exp(0.5*d35);
AlphaSBase::doinit();
}
vector<Energy> O2AlphaS::LambdaQCDs() const
{
vector<Energy> output(4,_lambdas[3]);
output.push_back(_lambdas[4]);
output.push_back(_lambdas[5]);
output.push_back(_lambdas[5]);
return output;
}
double O2AlphaS::value(Energy2 scale, const StandardModelBase &) const
{
Energy rs=sqrt(scale);
if(scale<sqr(_lambdas[5])) {
- cerr << "O2AlphaS called with scale less than Lambda QCD "
- << "scale = " << rs/MeV << " MeV and "
- << "Lambda = " << _lambdas[5]/MeV << " MeV\n";
- generator()->log() << "O2AlphaS called with scale less than Lambda QCD "
- << "scale = " << rs/MeV << " MeV and "
- << "Lambda = " << _lambdas[5]/MeV << " MeV\n";
+ generator()->logWarning(Exception()
+ << "O2AlphaS called with scale less than Lambda QCD "
+ << "scale = " << rs/MeV << " MeV and "
+ << "Lambda = " << _lambdas[5]/MeV << " MeV"
+ << Exception::warning);
return 0.;
}
double rho=2.*log(rs/_lambdas[5]),rat(log(rho)/rho);
double rlf;
if(rs>_threshold[5]) rlf=_bcoeff[5]*rho/(1.-_ccoeff[5]*rat)+_match[5];
else if(rs>_threshold[4]) rlf=_bcoeff[4]*rho/(1.-_ccoeff[4]*rat);
else if(rs>_threshold[3]) rlf=_bcoeff[3]*rho/(1.-_ccoeff[3]*rat)+_match[4];
else rlf=_bcoeff[2]*rho/(1.-_ccoeff[2]*rat)+_match[3];
// must be possible
if(rlf<=0.) {
- generator()->log() << "O2AlphaS coupling less than zero \n";
+ generator()->logWarning(Exception() << "O2AlphaS coupling less than zero"
+ << Exception::warning) ;
return 0.;
}
return 1./rlf;
}

File Metadata

Mime Type
text/x-diff
Expires
Tue, Nov 19, 4:53 PM (1 d, 12 h)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
3798137
Default Alt Text
(6 KB)

Event Timeline