Two recent experiments have demonstrated that the effective $\rho$-mass in nuclear medium, as extracted from the ${}^3\mathrm{He}(\gamma ,{\pi }^{+}{\pi }^{-})$ reaction, is substantially reduced. This has been advocated as an indication of partial restoration of chiral symmetry in nuclear matter. We show that even in the absence of chiral symmetry, effective mean field nuclear matter models can explain these findings quantitatively.

• Received 17 February 1999

DOI:https://doi.org/10.1103/PhysRevC.60.018202