import math


def gamma_axial_neutrino(m_med, g_l=0.0):
    """Function to calculate neutrino width of an axial vector mediator

    :param m_med: mediator mass
    :type m_med: float
    :param g_l: lepton coupling, defaults to 0.0
    :type g_l: float, optional
    """
    return 3 * g_l**2 / (24 * math.pi) * m_med