The relativistic chiral SU (3) Lagrangian is used to describe kaon-nucleon scattering imposing constraints from the pion-nucleon sector and the axial-vector coupling constants of the baryon octet states. We solve the covariant coupled-channel BetheSalpeter equation with the interaction kernel truncated at chiral order Q 3 where we include only those terms which are leading in the large N c limit of QCD. The baryon decuplet states are an important explicit ingredient in our scheme, because together with the baryon octet states they form the large N c baryon ground states of QCD. Part of our technical developments is a minimal chiral subtraction scheme within dimensional regularization, which leads to a manifest realization of the covariant chiral counting rules. All SU(3) symmetry-breaking effects are well controlled by the combined chiral and large N c expansion, but still found to play a crucial role in understanding the empirical data. We achieve an excellent description of the data set typically up to laboratory momenta of p lab ≃ 500 MeV.

A new scheme for testing nuclear matter equations of state (EoSs) at high densities using constraints from neutron star (NS) phenomenology and a flow data analysis of heavy-ion collisions is suggested. An acceptable EoS shall not allow the direct Urca process to occur in NSs with masses below 1.5M , and also shall not contradict flow and kaon production data of heavy-ion collisions. Compact star constraints include the mass measurements of 2.1 ± 0.2M (1σ level) for PSR J0751+1807 and of 2.0 ± 0.1M from the innermost stable circular orbit for 4U 1636-536, the baryon mass-gravitational mass relationships from Pulsar B in J0737-3039 and the mass-radius relationships from quasiperiodic brightness oscillations in 4U 0614+09 and from the thermal emission of RX J1856-3754. This scheme is applied to a set of relativistic EoSs which are constrained otherwise from nuclear matter saturation properties. We demonstrate on the given examples that the test scheme due to the quality of the newly emerging astrophysical data leads to useful selection criteria for the high-density behavior of nuclear EoSs.

We study heavy-light meson resonances with quantum numbers J P = 0 + and J P = 1 + in terms of the non-linear chiral SU(3) Lagrangian. At leading order a parameter-free prediction is obtained for the scattering of Goldstone bosons off heavy-light pseudo-scalar and vector mesons once we insist on approximate crossing symmetry of the unitarized scattering amplitude. The recently announced narrow open charm states observed by the BABAR and CLEO collaborations are reproduced. We suggest the existence of states that form an anti-triplet and a sextet representation of the SU (3) group. In particular, so far unobserved narrow isospinsinglet states with negative strangeness are predicted. The open bottom states with (I, S) = (0, −1) are anticipated at 5761 MeV (J P = 0 + ) and 5807 MeV (J P = 1 + ). For the anti-triplet states our results differ most significantly from predictions that are based on a linear realization of the chiral SU(3) symmetry in the open bottom sector. Strongly bound 0 + -and 1 + -states with (I, S) = (0, 1) at 5643 MeV and 5690 MeV are predicted.

We study J P = (

We study meson resonances with quantum numbers J P = 1 + in terms of the chiral SU(3) Lagrangian. At leading order a parameter-free prediction is obtained for the scattering of Goldstone bosons off vector mesons with J P = 1 − once we insist on approximate crossing symmetry of the unitarized scattering amplitude. A resonance spectrum arises that is remarkably close to the empirical pattern. In particular, we find that the strangeness-zero resonances h 1 (1380), f 1 (1285) and b 1 (1235) are formed due to strong KK µ andK K µ channels. This leads to large coupling constants of those resonances to the latter states.