Chiral effective Lagrangian description of nuclear matter with in-medium pion effect

By including the in-medium pion effect, we study the description of nuclear matter based on the non-linear chiral Lagrangian at the leading order. An-medium effective Lagrangian is constructed without the necessity of introducing the phenomenological scalar-isoscalar field. At the mean-field level, the in-medium Lagrangian description of nuclear matter is shown to be compatible with that obtained from the Brown-Rho scaled model