[HW3 Q2.7] Clarification of symbols
Clarification of symbols
In the following equation of Q2.7
cis the speed of light in vacuum
\nu_nis the n-th Matsubara frequency (in Hz or s
Overall $r_n$ is a unitless number. Larger $r_n$ means the separation
d is too long for the EM wave to travel compared with
\nu_n, hence the retardation effect.