8115045
Meson and Baryon resonances
In this talk I review recent advances on the structure of the meson and baryon resonances which can be dynamically generated from the interaction of mesons or mesons and baryons. Particular emphasis is put on results involving vector mesons, which bring new light into the nature of some of the observed higher mass mesons and baryons and make predictions for new states.
119190125
Finite volume effects in pion-kaon scattering and reconstruction of the κ(800) resonance
A bstractSimulating the κ(800) on the lattice is a challenging task that starts to become feasible due to the rapid progress in recent-years lattice QCD calculations. As the reso- nance is broad, special attention to finite-volume effects has to be paid, because no sharp resonance signal as from avoided level crossing can be expected. In the present article, we investigate the finite volume effects in the framework of unitarized chiral perturbation theory using next-to-leading order terms. After a fit to meson-meson partial wave data, lattice levels for πK scattering are predicted. In addition, levels are shown for the quantum numbers in which the σ(600), f0(980), a0(980), φ(1020), K*(892), and ρ(770) appear, as well as the repulsive channels. Methods to extract the κ(800) signal from the lattice spec- trum are presented. Using pseudo-data, we estimate the precision that lattice data should have to allow for a clear-cut extraction of this resonance. To put the results into con- text, in particular the required high precision on the lattice data, the σ(600), the P -wave resonances K*(892) and ρ(770), and the repulsive πK, ππ phases are analyzed as well.
46785821
Chiral dynamics and S-wave contributions in semileptonic B decays
A bstractThe flavor-changing neutral current process b → sl+l− is beneficial to testing the standard model and hunting for new physics scenarios. In exclusive decay modes like B → K*(892)l+l−, the S-wave effects may not be negligible and thus have to be reliably estimated. Using the scalar form factors derived from dispersion relations in two channels and matched to Chiral Perturbation Theory, we investigate the S-wave contributions in $ {{\overline{B}}^0}\to {K^{-}}{\pi^{+}}{l^{+}}{l^{-}} $, with the Kπ invariant mass lying in the vicinity of the mass of K*(892), and Bs → K−K+l+l− with mKK ~ mϕ. We find that the S-wave will modify differential decay widths by about 10% in the process of $ {{\overline{B}}^0}\to {K^{-}}{\pi^{+}}{l^{+}}{l^{-}} $ and about 5% in Bs → K−K+l+l−. A forward-backward asymmetry for the charged kaon in the final state arises from the interference between the S-wave and P-wave contributions. The measurement of this asymmetry offers a new way to determine the variation of the Kπ S-wave phase versus the invariant mass.
53708602
Scalar mesons moving in a finite volume and the role of partial wave mixing
Phase shifts and resonance parameters can be obtained from finite-volume lattice spectra for interacting pairs of particles, moving with non-zero total momentum. We present a simple derivation of the method that is subsequently applied to obtain the ππ and πK phase shifts in the sectors with total isospin I = 0 and I = 1/2 , respectively. Considering different total momenta, one obtains extra data points for a given volume that allow for a very efficient extraction of the resonance parameters in the infinite-volume limit. Corrections due to the mixing of partial waves are provided. We expect that our results will help to optimize the strategies in lattice simulations, which aim at an accurate determination of the scattering and resonance properties.
204016596
Meson baryon interaction in the hadron exchange picture
Elastic πN scattering and the reaction π+p→K+Σ+ are described simultaneously in a unitary coupled‐channels approach which respects analyticity. SU(3) flavor symmetry is used to relate the t‐ and u‐ channel exchanges that drive the meson‐baryon interaction in the different channels. Angular distributions, polarizations, and spin‐rotation parameters are compared with available experimental data. The pole structure of the amplitudes is extracted from the analytic continuation.
16407243
Kaon–nucleon scattering lengths from kaonic deuterium experiments revisited
Abstract We analyse the impact of the recent measurement of kaonic hydrogen X rays by the SIDDHARTA collaboration on the allowed ranges for the kaon–deuteron scattering length in the framework of non-relativistic effective field theory. Based on data from K ¯ N scattering only, we predict the kaon–deuteron scattering length A K d = ( − 1.46 + i 1.08 ) fm , with an estimated uncertainty of about 25% in both the real and the imaginary part.
30722169
Charge fluctuations and electric mass in a hot meson gas
Net charge fluctuations in a hadron gas are studied using an effective hadronic interaction. The emphasis of this work is to investigate the corrections of hadronic interactions to the charge fluctuations of a noninteracting resonance gas. Several methods such as loop, density, and virial expansions are employed. The calculations are also extended to SU(3), and some resummation schemes are considered. Although the various corrections are sizable individually, they cancel to a large extent. As a consequence, we find that charge fluctuations are rather well described by the free resonance gas.