Spectral properties of $\rho$ meson in a magnetic field
  We calculate the rho meson mass in a weak magnetic field using effective $\rho\pi\pi$ interaction. It is seen that both $\rho^0$ and $\rho^\pm$ masses decrease with the magnetic field in vacuum. $\rho$ meson dispersion relation has been calculated and shown to be different for $\rho^0$ and $\rho^\pm$. We also calculate the $\rho\pi\pi$ decay width and spectral functions of $\rho^0$ and $\rho^\pm$. The width is seen to decrease with $eB$ and the spectral functions become narrower. 
Snigdha Ghosh, Arghya Mukherjee, Mahatsab Mandal, Sourav Sarkar and   Pradip Roy
nucl-th hep-ph