The pion's electromagnetic form factor at small momentum transfer in full lattice QCD

Abstract

We compute the electromagnetic form factor of a "pion" with mass m_pi=330MeV at low values of Q^2\equiv -q^2, where q is the momentum transfer. The computations are performed in a lattice simulation using an ensemble of the RBC/UKQCD collaboration's gauge configurations with Domain Wall Fermions and the Iwasaki gauge action with an inverse lattice spacing of 1.73(3)GeV. In order to be able to reach low momentum transfers we use partially twisted boundary conditions using the techniques we have developed and tested earlier. For the pion of mass 330MeV we find a charge radius given by <r_pi^2>_{330MeV}=0.354(31)fm^2 which, using NLO SU(2) chiral perturbation theory, extrapolates to a value of <r_pi^2>=0.418(31)fm^2 for a physical pion, in agreement with the experimentally determined result. We confirm that there is a significant reduction in computational cost when using propagators computed from a single time-slice stochastic source compared to using those with a point source; for m_pi=330MeV and volume (2.74fm)^3 we find the reduction is approximately a factor of 12.

20 pages, 3 figures

References in corpus (6)

• Use of stochastic sources for the lattice determination of light quark physics
• Flavor Twisted Boundary Conditions, Pion Momentum, and the Pion Electromagnetic Form Factor
• Electromagnetic form factors of the pion and kaon from the instanton vacuum
• The QCDOC supercomputer: hardware, software, and performance
• Pseudo-scalar meson form factors with maximally twisted Wilson fermions at Nf = 2
• Pion form factor from all-to-all propagators of overlap quarks

Cited by in corpus (3)

• Use of stochastic sources for the lattice determination of light quark physics
• Vector Meson Dominance as a first step in a systematic approximation: the pion vector form factor
• New constraints on the Pion EM form factor using Pi'(-Q^2)