All Problems Elementary Particles
Problem 6.304
Find the threshold energy of gamma quantum required to form (a) an electron-positron pair in the field of a stationary electron; (b) a pair of pions of opposite signs in the field of a stationary proton.
(a) \(\varepsilon_{t h}=4 m_{e}=2.04 \mathrm{MeV}\) (b) \(\varepsilon_{t h}=2 m_{\pi}\left(1+m_{\pi} / m_{p}\right)= 320 MeV\)