Speaker
Mr
Shuntaro Sakai
(Kyoto University)
Description
We explore how the \eta-\pi^0 mixing angle and the \eta meson
decay into \pi^+\pi^-\pi^0 and 3\pi^0 are modified in the nuclear
medium on the basis of chiral effective field theory.
We find that the larger isospin-asymmetry \delta\rho\equiv \rho_n-\rho_p and the smaller total baryon density \rho\equiv\rho_n+\rho_p, the more enhanced the mixing angle.
It turns out that the effect of the
total baryon density on the decay widths overwhelms that
coming from the isospin-asymmetry, and the higher the \rho, the more
enhanced the decay widths;
the width for the \pi^+\pi^-\pi^0 decay is enhanced with a factor two to three at the normal density \rho_0 with a minor increase due to
\delta\rho, while that for the 3\pi^0 decay shows only a small
increase of around 10 percent even at \rho_0.
We find that the \rho dependence of the decay width is caused by the six-body vertex which involves two nucleon lines as well as the four pseudo-scalar bosons and hence only comes into play in the nuclear medium.
We show that the \rho dependence is nicely expressed as a renormalization of the pion decay constant f^{\ast}_{\pi}(\rho), which is interpreted to represent the partial restoration of chiral symmetry in the nuclear medium.
Primary author
Mr
Shuntaro Sakai
(Kyoto University)
Co-author
Prof.
Teiji Kunihiro
(Kyoto University)
