# constants.py
ALPHA = 1 / 137.035999084  # fine-structure constant
EULER_GAMMA = 0.57721566490153286  # Euler-Mascheroni constant
HBAR_C_MEV_FM = 197.3269804  # MeV * fm
ME_MEV = 0.510998950  # electron rest mass in MeV / c^2
ME_KEV = ME_MEV * 1000.0  # electron rest mass in keV
MP_MEV = 938.272088816  # proton rest mass in MeV / c^2
R0_FM = 1.2  # nuclear radius parameter in fm