ShowerAlphaQCD.h

// -*- C++ -*-
//
// ShowerAlphaQCD.h is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2019 The Herwig Collaboration
//
// Herwig is licenced under version 3 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef HERWIG_ShowerAlphaQCD_H
#define HERWIG_ShowerAlphaQCD_H
//
// This is the declaration of the ShowerAlphaQCD class.
//
 
#include "Herwig/Shower/ShowerAlpha.h"
 
namespace Herwig {
 
using namespace ThePEG;
 
class ShowerAlphaQCD: public ShowerAlpha {
 
public:
 
  ShowerAlphaQCD() : ShowerAlpha(), 
                     _qmin(0.630882*GeV), _asType(1), _asMaxNP(1.0), 
                     _thresholds(4), _lambda(4),
                     _nloop(3),_thresopt(false),
                     _alphain(0.118),_tolerance(1e-10),
                     _maxtry(100),_alphamin(0.),_val0(1.), _optInputScale(91.1876_GeV) {}
 
public:
 
  virtual double value(const Energy2 scale) const;
 
  virtual double overestimateValue() const;
 
  virtual double ratio(const Energy2 scale,double factor =1.) const;
 
  virtual void initialize() { doinit(); }
 
  string value(string);
 
  string check(string args);
 
 
  Energy lambdaQCD(unsigned int nf) {
    if      (nf <= 3)        return _lambda[0];
    else if (nf==4 || nf==5) return _lambda[nf-3];
    else                     return _lambda[3];
  }
 
  const vector<Energy>& quarkMasses() const { return _quarkMasses; }
 
public:
 
  void persistentOutput(PersistentOStream & os) const;
 
  void persistentInput(PersistentIStream & is, int version);
 
  static void Init();
 
protected:
 
  virtual IBPtr clone() const;
 
  virtual IBPtr fullclone() const;
 
 
protected:
 
  virtual void doinit();
 
private:
 
  Energy computeLambda(Energy match, double alpha, unsigned int nflav) const;
 
  pair<short, Energy> getLamNfTwoLoop(Energy q) const;
 
private:
 
  ShowerAlphaQCD & operator=(const ShowerAlphaQCD &) = delete;
 
private:
 
  Energy _qmin;
 
  int _asType;
 
  double _asMaxNP;
 
  vector<Energy> _thresholds;
 
  vector<Energy> _lambda;
 
  unsigned int _nloop;
 
  bool _thresopt;
 
  double _alphain;
 
  double _tolerance;
 
  unsigned int _maxtry;
 
  double _alphamin;
 
  double _val0;
 
  Energy _optInputScale;
 
  vector<Energy> _quarkMasses;
};
 
}
 
#endif /* HERWIG_ShowerAlphaQCD_H */