Decay of the rho and a1 mesons on the lattice using distillation

Abstract

We extract the P-wave ππ phase shift for five values of pion relative momenta, which gives information on the ρ resonance. The Breit-Wigner formula describes the ππ phase shift dependence nicely and we extract m ρ = 792(7)(8) MeV and the coupling g ρππ = 5.13(20) at our m π = 266 MeV. We extract the P-wave scattering length a ππ l=1 = 0.082(10)(3) fm 3 from the state with the lowest pion relative momenta. We also determine the S-wave ρπ phase shift for two values of relative momenta, which provides parameters of the lowest axial resonance a 1 (1260). Using the Breit-Wigner fit we extract m a1 = 1.44(4) GeV and the coupling g a 1 ρπ = 1.1(3) GeV. From the lowest state we also extract the ρπ scattering length a ρπ l=0 = 0.23(12) fm for our m π. The simulation is performed using one N f = 2 ensemble of gauge configurations with cloverimproved Wilson quarks. The phase shifts are determined from the lowest two energy-levels, which are obtained by the variational analysis with a number of quark-antiquark and mesonmeson interpolators. The correlation functions are calculated using the distillation method with the Laplacian Heaviside (LapH) smearing of quarks.

Axial resonances a 1(1260), b 1(1235) and their decays from the lattice

“…The width Γ[b 1 → ωπ] was extracted based on the amplitude method [17] and reasonable agreement with experiment was found (see figure 3 of [16]). The a 1 has never been simulated taking into account its strong decay, with exception of our preliminary results [18].…”

S-waveKK*interactions in a finite volume and thefGeng1, Ren2, Zhou3 et al. 2015Phys. Rev. D292330View full textAdd to dashboardCite

“…This was the case on the φρ system looking for the a 1 (1260) resonance in Refs. [51,52] and in the KD system in Ref. [29], where the levels associated to the coupled channel ηD s also did not show up in the simulation.…”

Pseudoscalar meson and vector meson interactions and dynamically generated axial-vector mesons

“…It is not clear whether the scenario of these states being dynamically generated will change when higher order kernels are included. Given the fact that lately there have been attempts to study these states on the lattice [26,27], such a study is urgently needed. Recently it has been shown in the DK sector that although inclusion of higher-order kernels do not change qualitatively the conclusions, they do have impact on the quantitative description of the lattice 1 The two-pole scenario is also found for the Λ(1405) [14,16], which seems to be a universal feature of all the studies based on coupled channel chiral dynamics.…”