Energy dependence of the {\rho} resonance in {\pi}{\pi} elastic scattering from lattice QCD

Understand

We determine the energy-dependent amplitude for elastic {\pi}{\pi} P-wave scattering in isospin-1 by computing part of the discrete energy spectrum of QCD in finite cubic boxes.

• We observe a rapidly rising phase shift that can be well described by a single {\rho} resonance.
• The spectrum is obtained from hadron correlators computed using lattice QCD with light quark masses corresponding to m{\pi} ~ 400 MeV.
• Variational analyses are performed with large bases of hadron interpolating fields including, as well as fermion bilinears that resemble q-qbar constructions, also operators that resemble pairs of pions with definite relative and total momentum.