The European Physical Journal C

ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)

Table of Contents

Abstract Volume 2 Issue 2 (1998) pp 269-286

theoretical physics:
New results in $\rho^0$ meson physics

M. Benayoun (1), S. Eidelman (2), K. Maltman (3)(4)(5), H.B. O'Connell (4)(6), B. Shwartz (2), A.G. Williams (4)(5)

(1) LPNHE des Universités Paris VI et VII-IN2P3, Paris, France (e-mail: benayoun@in2p3.fr)
(2) Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia (e-mail: eidelman@vxcern.cern.ch)
(3) Mathematics and Statistics, York University, 4700 Keele St., North York, Ontario, Canada M3J 1P3 (e-mail: maltman@fewbody.phys.yorku.ca)
(4) Department of Physics and Mathematical Physics, University of Adelaide 5005, Australia (e-mail: awilliam@physics.adelaide.edu.au)
(5) Special Research Centre for the Subatomic Structure of Matter, University of Adelaide 5005, Australia
(6) Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506, USA (e-mail: hoconnel@ruthless.pa.uky.edu)

Received: 1 August 1997 / Revised version: 4 December 1997 / Online publication: February 26, 1998

Abstract. We compare the predictions of a range of existing models based on the Vector Meson Dominance hypothesis with data on $e^+e^-\rightarrow \pi^+\pi^-$ and $e^+e^-\rightarrow \mu^+\mu^-$ cross-sections and the phase and near-threshold behavior of the timelike pion form factor, with the aim of determining which (if any) of these models is capable of providing an accurate representation of the full range of experimental data. We find that, of the models considered, only that proposed by Bando et al. is able to consistently account for all information, provided one allows its parameter $a$ to vary from the usual value of 2 to 2.4. Our fit with this model gives a point-like coupling $\gamma \pi^+ \pi^-$ of magnitude $\simeq -e/6$, while the common formulation of VMD excludes such a term. The resulting values for the $\rho$ mass and $\pi^+\pi^-$ and $e^+e^-$ partial widths as well as the branching ratio for the decay $\omega \rightarrow \pi^+\pi^-$ obtained within the context of this model are consistent with previous results.

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Online publication: April 8, 1998
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