Constraining the low energy pion electromagnetic form factor with space-like data

Abstract

The pionic contribution to the g-2 of the muon involves a certain integral over the the modulus squared of F_\pi(t), the pion electromagnetic form factor. We extend techniques that use cut-plane analyticity properties of F_\pi(t) in order to account for present day estimates of the pionic contribution and experimental information at a finite number of points in the space-like region. Using data from several experiments over a large kinematic range for |t|, we find bounds on the expansion coefficients of F_\pi(t), sub-leading to the charge radius. The value of one of these coefficients in chiral perturbation theory respects these bounds. Furthermore, we present a sensitivity analysis to the inputs. A brief comparison with results in the literature that use observables other than the g-2 and timelike data is presented.

Comments: 11 pages in EPJ journal style, to appear in European Physical Journal C