Dynamical generation of axial-vector mesons

초록

We present recent results on the dynamical generation of the a1, h1, and b1 axial-vector mesons. We demonstrate the emergence of the a1 and h1 mesons from the πρ scattering process, based on the coupled-channel formalism with the πρ andK ?K ? ( ?KK?) channels. This is achieved by constructing kernel amplitudes using the effective Lagrangian and computing the coupled integral equation for πρ scattering. By performing the partial-wave expansion, we explicitly show that the a1(1260) meson arises as a K ?K ? molecular state, generated only by including the K ?K ? ( ?K K?) channel. The pole position of the a1 meson is determined to be at √sR = (1170.7 ? i173.0) MeV. We also investigate four different h1 mesons by coupling additional channels such as ηω and η?, and find that h1(1415) is strongly coupled to the K ?K ? and η? channels, indicating its significant strange quark content. Additionally, we report a novel observation that the b1 meson has a two-pole structure that arises from πω scattering, with the interference of these two-pole resonances resulting in the appearance of b1(1235).