smash::KaonNucleonRatios Class Reference

#include <parametrizations.h>

Calculate and store isospin ratios for K N -> K Delta reactions.

The ratios are given by the squared Clebsch-Gordan coefficient for the respective reaction, divided by the sum of the squared coefficients of all possible isospin-symmetric reactions. They are used when calculating the corresponding cross sections from the parametrizations of experimental data.

Definition at line 459 of file parametrizations.h.

Public Member Functions
	KaonNucleonRatios ()
	Create an empty K N -> K Delta isospin ratio storage. More...
double	get_ratio (const ParticleType &a, const ParticleType &b, const ParticleType &c, const ParticleType &d) const
	Return the isospin ratio of the given K N -> K Delta cross section. More...

Private Attributes
std::unordered_map< std::pair< uint64_t, uint64_t >, double, pair_hash >	ratios_
	Internal representation of isospin weights once calculated. More...

Constructor & Destructor Documentation

KaonNucleonRatios()

smash::KaonNucleonRatios::KaonNucleonRatios ( )

inline

Create an empty K N -> K Delta isospin ratio storage.

Definition at line 467 of file parametrizations.h.

: ratios_({}) {}

Member Function Documentation

get_ratio()

double smash::KaonNucleonRatios::get_ratio	(	const ParticleType &	a,
		const ParticleType &	b,
		const ParticleType &	c,
		const ParticleType &	d
	)		const

Return the isospin ratio of the given K N -> K Delta cross section.

On the first call all ratios are calculated.

Definition at line 648 of file parametrizations.cc.

                                                                 {
  /* If this method is called with anti-nucleons, flip all particles to
   * anti-particles;
   * the ratio is equal */
  int flip = 0;
  for (const auto& p : {&a, &b, &c, &d}) {
    if (p->is_nucleon()) {
      if (flip == 0) {
        flip = p->antiparticle_sign();
      } else {
        assert(p->antiparticle_sign() == flip);
      }
    }
  }
  const auto key = std::make_pair(
      pack(a.pdgcode().code() * flip, b.pdgcode().code() * flip),
      pack(c.pdgcode().code() * flip, d.pdgcode().code() * flip));
  if (ratios_.empty()) {
    initialize(ratios_);
  }
  return ratios_.at(key);
}

Member Data Documentation

ratios_

std::unordered_map<std::pair<uint64_t, uint64_t>, double, pair_hash> smash::KaonNucleonRatios::ratios_

mutableprivate

Internal representation of isospin weights once calculated.

Definition at line 463 of file parametrizations.h.

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

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