smash::TwoBodyDecayStable Class Reference

#include <decaytype.h>

TwoBodyDecayStable represents a decay type with two stable final-state particles.

Definition at line 130 of file decaytype.h.

Inheritance diagram for smash::TwoBodyDecayStable:

Collaboration diagram for smash::TwoBodyDecayStable:

Public Member Functions
	TwoBodyDecayStable (ParticleTypePtrList part_types, int l)
	Construct a TwoBodyDecayStable. More...
double	width (double m0, double G0, double m) const override
	Get the mass-dependent width of a two-body decay into stable particles according to Manley:1992yb [33]. More...
double	in_width (double m0, double G0, double m, double m1, double m2) const override
	Get the mass-dependent in-width for a resonance formation process from two stable particles according to Manley:1992yb [33], see also Effenberger:1999wlg [18], eq. More...
Public Member Functions inherited from smash::TwoBodyDecay
	TwoBodyDecay (ParticleTypePtrList part_types, int l)
	Construct a TwoBodyDecay. More...
unsigned int	particle_number () const override
bool	has_particles (ParticleTypePtrList list) const override
double	threshold () const
Public Member Functions inherited from smash::DecayType
	DecayType (ParticleTypePtrList part_types, int l)
	Construct a DecayType. More...
virtual	~DecayType ()=default
	Virtual Destructor. More...
virtual bool	has_mother (ParticleTypePtr mother) const
const ParticleTypePtrList &	particle_types () const
int	angular_momentum () const

Protected Member Functions
double	rho (double m) const override
	This is a virtual helper method which is used to write the width as Gamma(m) = Gamma_0 * rho(m) / rho(m_0). More...

Additional Inherited Members
Protected Attributes inherited from smash::DecayType
ParticleTypePtrList	particle_types_
	final-state particles of the decay More...
int	L_
	angular momentum of the decay More...

Constructor & Destructor Documentation

TwoBodyDecayStable()

smash::TwoBodyDecayStable::TwoBodyDecayStable	(	ParticleTypePtrList	part_types,
		int	l
	)

Construct a TwoBodyDecayStable.

Parameters

[in]	part_types	Final-state particles of the decay.
[in]	l	Angular momentum of the decay.

Returns

The constructed object.

Definition at line 73 of file decaytype.cc.

    : TwoBodyDecay(part_types, l) {
  if (!(part_types[0]->is_stable() && part_types[1]->is_stable())) {
    throw std::runtime_error(
        "Error: Unstable particle in TwoBodyDecayStable constructor: " +
        part_types[0]->pdgcode().string() + " " +
        part_types[1]->pdgcode().string());
  }
}

Member Function Documentation

width()

double smash::TwoBodyDecayStable::width ( double  m0, double  G0, double  m  ) const

overridevirtual

Get the mass-dependent width of a two-body decay into stable particles according to Manley:1992yb [33].

Parameters

m0	Pole mass of the decaying particle [GeV].
G0	Partial width at the pole mass [GeV].
m	Actual mass of the decaying particle [GeV].

Implements smash::DecayType.

Reimplemented in smash::TwoBodyDecayDilepton.

Definition at line 91 of file decaytype.cc.

                                                                     {
  assert(rho(m0) != 0);
  return (m <= threshold()) ? 0. : G0 * rho(m) / rho(m0);
}

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in_width()

double smash::TwoBodyDecayStable::in_width ( double  m0, double  G0, double  m, double  m1, double  m2  ) const

overridevirtual

Get the mass-dependent in-width for a resonance formation process from two stable particles according to Manley:1992yb [33], see also Effenberger:1999wlg [18], eq.

(2.77).

Parameters

m0	Pole mass of the produced resonance [GeV].
G0	Partial width at the pole mass [GeV].
m	Actual mass of the produced resonance [GeV].
m1	Actual mass of the first incoming particle [GeV].
m2	Actual mass of the second incoming particle [GeV].

Implements smash::DecayType.

Definition at line 96 of file decaytype.cc.

                                                  {
  // in-width = out-width
  return width(m0, G0, m);
}

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rho()

double smash::TwoBodyDecayStable::rho ( double  mass ) const

overrideprotectedvirtual

This is a virtual helper method which is used to write the width as Gamma(m) = Gamma_0 * rho(m) / rho(m_0).

This ensures that the width is properly normalized at the pole mass to Gamma(m_0) = Gamma_0. By default rho simply equals one, which corresponds to a constant width.

Parameters

[in]

mass

Resonance mass of the decay.

Returns

Width of the decay at the given mass.

Reimplemented from smash::TwoBodyDecay.

Definition at line 83 of file decaytype.cc.

                                             {
  // Determine momentum of outgoing particles in rest frame of the resonance
  const double p_ab =
      pCM(m, particle_types_[0]->mass(), particle_types_[1]->mass());
  // determine rho(m)
  return p_ab / m * blatt_weisskopf_sqr(p_ab, L_);
}

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The documentation for this class was generated from the following files:

• src/include/smash/decaytype.h
• src/decaytype.cc