In-Medium Chiral Perturbation Theory

Abstract

We report about a systematic study (see U.‐G. Meisner, J.A. Oller and A. Wirzba, nucl‐th/0109026) of the properties of pions and external sources in nuclear matter. An explicit expression of the generating functional of two‐flavor low‐energy QCD with external sources in the presence of non‐vanishing nucleon densities has been derived recently (see J.A. Oller, hep‐ph/0101204). The corresponding in‐medium chiral perturbation theory (CHPT) lagrangian is non‐covariant as well as non‐local and formulated in terms of pions and external sources only. Within this approach the (chiral) power counting rules for the calculation of in‐medium pion properties are derived in the so‐called standard and in the non‐standard scenario where the residual nucleon energies are of the order of the pion mass or of the order of the nucleonic kinetic energy, respectively. Also the pertinent scales for the range of applicability of these two perturbative expansions are established. In the standard scenario, we report on a systematic...