anonymous_namespace{crosssectionsphoton.cc} Namespace Reference

Functions
double	HeavisideTheta (double x)
	Heavyside step function. More...
double	cut_off (const double sigma_mb)
	Cross section after cut off. More...

Function Documentation

HeavisideTheta()

double anonymous_namespace{crosssectionsphoton.cc}::HeavisideTheta

(

double

x

)

Heavyside step function.

Parameters

[in]

x

value to be compared to zero

Returns

0 if x is smaller than 0, else 1

Definition at line 30 of file crosssectionsphoton.cc.

                                {
  if (x >= 0.0) {
    return 1.0;
  } else {
    return 0.0;
  }
}

Here is the caller graph for this function:

cut_off()

double anonymous_namespace{crosssectionsphoton.cc}::cut_off

(

const double

sigma_mb

)

Cross section after cut off.

Photon cross sections diverge tremendously at the threshold which becomes particularly problematic when running with broad rho mesons. Then the actual photon cross section is used for the weight: W = Sigma_photon/Sigma_hadron. If the photon cross section diverges, the weight becomes huge and we significantly overestimate photon production. This cutoff fixes the problem.

Either the cross section is returned or, if the cross section i larger than the cut off, the cut off value is returned.

Parameters

[in]

sigma_mb

cross section before cut off [mb]

Returns

Cross section after cut off [mb]

Definition at line 53 of file crosssectionsphoton.cc.

                                      {
  constexpr double maximum_cross_section_photon = 200.0;  // [mb]
  return (sigma_mb > maximum_cross_section_photon)
             ? maximum_cross_section_photon
             : sigma_mb;
}

Here is the caller graph for this function: