Eur. Phys. J. C (2008) 54: 461-470
https://doi.org/10.1140/epjc/s10052-008-0533-6

Regular Article - Theoretical Physics

Constraining the low-energy pion electromagnetic form factor with spacelike data

Centre for High Energy Physics, Indian Institute of Science, Bangalore, 560 012, India

^* e-mail: anant@cts.iisc.ernet.in

Received: 14 December 2007
Published online: 1 February 2008

Abstract

The pionic contribution to the g-2 of the muon involves a certain integral over the modulus squared of F_π(t), the electromagnetic form factor of the pion. We extend techniques that use cut-plane analyticity properties of F_π(t) in order to account for present day estimates of the pionic contribution and experimental information at a finite number of points in the spacelike region. Using data from several experiments over a large kinematic range for |t|, we find bounds on the expansion coefficients of F_π(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.