Mass modification of phi meson measured in 12-GeV p+A reaction at KEK-PS E325

The experiment KEK-PS E325 has measured $e^+e^-$ and $K^+K^-$ pairs produced in 12 GeV p+A reaction, in oder to study the chiral property of dense nucler matter through the analysis of invariant mass spectra. We have already reported modification of $\rho$ and/or $\omega$ mesons in PRL.86,5019(2001) and nucl-ex/0504016. In this talk, we will present our new results which show the modification of $\phi$ meson at normal nuclear density. Discussions will be made based on the observations both in $e^+e^-$ and $K^+K^-$ invariant mass spectra.