Raúl A. Briceño

Isoscalar ππ Scattering and the σ Meson Resonance from QCD

We present for the first time a determination of the energy dependence of the isoscalar ππ elastic scattering phase shift within a first-principles numerical lattice approach to QCD. Hadronic correlation functions are computed including all required quark propagation diagrams, and from these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum, we obtain the S-wave phase shift up to the KK[over ¯] threshold. Calculations are performed at two values of the u, d quark mass corresponding to m_{π}=236,391  MeV, and the resulting amplitudes are described in terms of a σ meson which evolves from a bound state below the ππ threshold at the heavier quark mass to a broad resonance at the lighter quark mass.

Relating the finite-volume spectrum and the two-and-three-particle S matrix for relativistic systems of identical scalar particles

Working in relativistic quantum field theory, we derive the quantization condition satisfied by coupled two- and three-particle systems of identical scalar particles confined to a cubic spatial volume with periodicity

Issues and opportunities in exotic hadrons

L

Scattering processes and resonances from lattice QCD

. This gives the relation between the finite-volume spectrum and the infinite-volume

Role of the Euclidean signature in lattice calculations of quasidistributions and other nonlocal matrix elements

\textbf 2 \to \textbf 2

Coupled

,

\pi\pi, K\bar{K}

\textbf 2 \to \textbf 3

scattering in

and

P

\textbf 3 \to \textbf 3

-wave and the

scattering amplitudes for such theories. The result holds for relativistic systems composed of scalar particles with nonzero mass