Parametrisation-free determination of the shape parameters for the pion electromagnetic form factor

Ananthanarayan, B and Caprini, I and Das, Diganta and Imsong, Sentitemsu I (2013) Parametrisation-free determination of the shape parameters for the pion electromagnetic form factor. In: EUROPEAN PHYSICAL JOURNAL C, 73 (8).

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Abstract

Recent data from high-statistics experiments that have measured the modulus of the pion electromagnetic form factor from threshold to relatively high energies are used as input in a suitable mathematical framework of analytic continuation to find stringent constraints on the shape parameters of the form factor at t = 0. The method uses also as input a precise description of the phase of the form factor in the elastic region based on Fermi-Watson theorem and the analysis of the pi pi scattering amplitude with dispersive Roy equations, and some information on the spacelike region coming from recent high precision experiments. Our analysis confirms the inconsistencies of several data on the modulus, especially from low energies, with analyticity and the input phase, noted in our earlier work. Using the data on the modulus from energies above 0.65 GeV, we obtain, with no specific parametrisation, the prediction < r(pi)(2)> is an element of (0.42, 0.44) fm(2) for the charge radius. The same formalism leads also to very narrow allowed ranges for the higher-order shape parameters at t = 0, with a strong correlation among them.

Item Type:	Journal Article
Publication:	EUROPEAN PHYSICAL JOURNAL C
Publisher:	SPRINGER
Additional Information:	Copyright of this article is belongs to SPRINGER
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Date Deposited:	21 Oct 2013 05:21
Last Modified:	21 Oct 2013 05:21
URI:	http://eprints.iisc.ac.in/id/eprint/47525

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