Interference effects in the X(4260) signal

TL;DR

This paper explains the X(4260) signal as a nonresonant cusp and interference effect, rather than a traditional resonance, providing a new perspective on its structure in electron-positron annihilation data.

Contribution

It introduces a simple form factor to describe open-charm decay ratios and models the X(4260) as a nonresonant cusp with interference effects, challenging the resonance interpretation.

Findings

Good fit to BABAR data with cusp model

Identification of oscillatory interference pattern

Discussion of alternative nonresonant enhancements

Abstract

We show that the long known puzzling branching ratios of open-charm decays in electron-positron annihilation can be reasonably described with a simple form factor, which strongly suppresses open channels far above threshold. Application to the electron-positron annihilation into J/psi+pion+pion data on the X(4260) enhancement recently reported by the BABAR Collaboration [arxiv:0808.1543] allows a good fit with a simple nonresonant cusp structure around the D(*)(s)+Dbar(*)(s) threshold. Moreover, we argue that a closer look at the data reveals an oscillatory pattern, which we model as an interference effect between a fast - OZI-allowed - and a slow - OZI-forbidden - J/psi+f(0)(980) mode. Other candidates for similar nonresonant enhancements are discussed.