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.

Collaboration diagram for smash::KaonNucleonRatios:

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 641 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);
}

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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