hazma.gamma_ray.gamma_ray_rambo¶

hazma.gamma_ray.gamma_ray_rambo(isp_masses, fsp_masses, cme, mat_elem_sqrd_tree=<function <lambda>>, mat_elem_sqrd_rad=<function <lambda>>, num_ps_pts=1000, num_bins=25)¶

Returns total gamma ray spectrum from a set of particles using a Monte Carlo.

Returns total gamma ray spectrum from a set of particles. This is done by first running a Monte Carlos to compute the non-radiative cross cross_section, \(\sigma(I \to F)\) from the non-radiative squared matrix element: \(|M(I \to F)|^2\). The differential radiative cross section, \(\frac{d\sigma(I \to F + \gamma)}{dE_{\gamma}}\), is then computed using a Monte Carlo using the radiative squared matrix element \(|M(I \to F + \gamma)|^2\). The spectrum is then

\[\frac{dN}{dE_{\gamma}} = \frac{1}{\sigma(I \to F)} \frac{d\sigma(I \to F + \gamma)}{dE_{\gamma}}\]

Parameters:

isp_masses (np.ndarray[double, ndim=1]) – Array of masses of the initial state particles. fsp_masses (np.ndarray[double, ndim=1]) – Array of masses of the final state particles. cme (double) – Center of mass energy of the process. mat_elem_sqrd_tree (double(*)(np.ndarray[double, ndim=1])) – Tree level squared matrix element. mat_elem_sqrd_rad (double(*)(np.ndarray[double, ndim=1])) – Radiative squared matrix element. num_ps_pts (int) – Number of Monte Carlo events to generate. num_bins (int) – Number of gamma ray energies to use.

Returns:

eng_gams (np.ndarray[double, ndim=1]) – Array of the gamma ray energies. dndes (np.ndarray[double, ndim=1]) – Array of the spectrum values evaluated at the gamma ray energies.

Examples

Compute spectrum from two fermions annihilating into a pair of charged fermions through a scalar mediator.

>>> from hazma import rambo
>>> from hazma.matrix_elements.simplified_models import xx_to_s_to_ff
>>> from hazma.matrix_elements.simplified_models import xx_to_s_to_ffg
>>>
>>> mx, ms = 120., 0.
>>> qf = 1.
>>> gsxx, gsff = 1.0, 1.0
>>>
>>> num_ps_pts = 10**6
>>> fsp_masses = np.array([mmu, mmu, 0.0])
>>> isp_masses = np.array([mx, mx])
>>> cme = 1000.
>>> num_bins = 150
>>>
>>> tree = lambda moms : xx_to_s_to_ff(moms, mx, mmu, ms, gsxx, gsff)
>>> radiative = lambda moms : xx_to_s_to_ffg(moms, mx, mmu,
..                                           ms, qf, gsxx, gsff)
>>>
>>> engs, dnde = gamma_ray.gamma_ray_rambo(isp_masses, fsp_masses, cme,
..                                         tree, radiative, num_ps_pts,
..                                         num_bins)