The phase-shift of isospin-2 pi-pi scattering from lattice QCD

Understand

Finite-volume lattice QCD calculations offer the possibility of extracting resonance parameters from the energy-dependent elastic phase-shift computed using the Luescher technique.

• In this letter, as a trial of the method, we report on the extraction of the non-resonant phase-shift for S and D-wave pi-pi isospin-2 scattering from dynamical lattice QCD computations.
• We define a variational basis of operators resembling pairs of pions of definite relative momentum and extract a spectrum of excited states that maps to phase-shifts at a set of discrete scattering momenta.
• Computations are performed with pion masses between 400 and 520 MeV on multiple spatial volumes.