Kπscattering for isospin12and32

Abstract

We simulate Kπ scattering in s wave and p wave for both isospins I = 1/2, 3/2 using quarkantiquark and meson-meson interpolating fields. We extract the elastic phase shifts δ at several values of the Kπ relative momenta. The resulting phases exhibit qualitative agreement with the experimental phases in all four channels. We express the s wave phase shifts near threshold in terms of the scattering length and the effective range. Our Kπ system has zero total momentum and is simulated on a single ensemble with two dynamical quarks, so results apply for mπ ≃ 266 MeV and mK ≃ 552 MeV in our simulation. The backtracking contractions in both I = 1/2 channels are handled by the use of Laplacian-Heavyside smeared quarks within the distillation method. Elastic phases are extracted from the energy levels using Lüscher's relations. In all four channels we observe the expected K(n)π(−n) scattering states, which are shifted due to the interaction. In both attractive I = 1/2 channels we observe additional states that are related to resonances; we attribute them to K * 0 (1430) in s wave and K * (892), K * (1410) and K * (1680) in p wave.

Tetraquarks, hadronic molecules, meson-meson scattering, and disconnected contributions in lattice QCD

“…Refs. [28,19,20,21,22] and references therein), the same conclusion can be obtained without the large-N arguments. In the low-energy regime of QCD, the lowest-lying pseudoscalar mesons π, K and η can be treated as the (Pseudo-)Goldstone bosons of the spontaneous chiral symmetry breaking, and their interactions among themselves and with other particles can be described by chiral perturbation theory (CHPT) [29,30].…”

“…[14]. It was shown later in a dynamical lattice calculation of Kπ scattering [19] that the energy level above and near the Kπ threshold is an artifact of neglecting the disconnected contributions. However, using similar lattice set-ups as those of Ref.…”

“…the distillation method [16], there have been lattice calculations including disconnected Wick contractions in the context of tetraquarks and meson-meson scattering, see, for instance, Refs. [17,18,19,20,22]. Energy levels above the meson-meson thresholds which may be interpreted as the σ and the κ were reported in Ref.…”

Scalar mesons and tetraquarks by means of lattice QCD

“…Such computations are very challenging using lattice QCD, but first results have recently been published (cf. [20,21]). We plan to perform similar computations with our setup in the near future.…”

A New Hadron Spectroscopy

“…In the theory, quarks and gluons are related to mesons and baryons by the long-distance regime of Quantum Chromodynamics (QCD), which remains the least understood aspect of the theory. Since first-principle lattice-QCD (LQCD) calculations are still not practical for most long-distance phenomena, 1 a number of models motivated by the color structure of QCD have been proposed. However, so far at least, predictions of these QCD-motivated models that pertain to the spectrum of hadrons have not had great success.…”