A consistent description of rho0 -> pi pi gamma decays including sigma(500) meson effects

Abstract

A consistent description of $\sigma (500)$ meson effects in ${\rho }^0\to {\pi }^0{\pi }^0\gamma$ and ${\pi }^{+}{\pi }^{-}\gamma$ decays is proposed in terms of reasonably simple amplitudes which reproduce the expected chiral-loop behaviour for large $m_{\sigma }$ values. For the neutral case, in addition to the well known $\omega$ exchange, there is an important contribution from the $\sigma (500)$ meson that is in agreement with recent experimental data. For the charged case, where the dominant contribution comes from bremsstrahlung, the effects of the $\sigma (500)$ meson are relevant only at high values of the photon energy and compatible with present data. A combined analysis of both processes with moderately improved experimental information should contribute decisively to clarify the status of this controversial $\sigma (500)$ meson.

11 pages, 3 figures, JHEP style. A comment on the O(p^4) ChPT calculation of the four-pseudoscalar amplitudes is included; a new discussion on the effects of our parametrization on the I=J=0 pi-pi phaseshift is also included. Final version accepted for publication

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Cited by in corpus (1)

• Role of resonances in rho^0 -> pi^+ pi^- gamma