Testing the consistency of the ωπ transition form factor with unitarity and analyticity

2015/05/20 by I. Caprini, Caprini, I.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #hep-ph

paper · pdf · doi:10.48550/arxiv.1505.05282

arxiv created 2015/05/20 · arxiv updated 2015/05/21

Abstract

We perform a dispersive analysis of the ωπ electromagnetic transition form factor, using as input the discontinuity provided by unitarity below the ωπ threshold and including for the first time experimental data on the modulus measured from e⁺e^-→ωπ⁰ at higher energies. The input leads to stringent parameterization-free constraints on the modulus of the form factor below the ωπ threshold, which are in disagreement with some experimental values measured from ω→ π⁰γ^* decay. We discuss the dependence on the input parameters in the unitarity relation, using for illustration an N/D formalism for the P partial wave of the scattering process ωπ→ ππ, improved by a simple prescription which simulates the rescattering in the crossed channels. Our results confirm the existence of a conflict between experimental data and theoretical calculations of the ωπ form factor in the region around 0.6 GeV and bring further arguments in support of renewed experimental efforts to measure more precisely the ω→π⁰γ^* decay.

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