Neutral pion decay into $\nu\bar{\nu}$ in dense skyrmion matter
  We study the weak decay of the neutral pion to a neutrino-antineutrino pair, $\pi^0\to \nu \bar{\nu}$, in the Skyrme model. In baryon free-space the process is forbidden by helicity while in a dense baryonic medium, the process becomes possible already to leading order in $G_F$ due to the break-down of Lorentz symmetry in the background medium. 
Alexander C. Kalloniatis (CSSM, Australia), Jonathan D. Carroll (CSSM,   Australia), Byung-Yoon Park (CSSM and Chungnam Nati...