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arXiv · 1311.2401

Meson loop singularity, exotic states' productions and decays near threshold

Qian Wang·Christoph Hanhart·Qiang Zhao
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Abstract

We investigate in detail the "triangle singularity" regions of meson loops where the corresponding intermediate mesons are nearly-on-shell and have relatively small momenta, and the two heavy mesons strongly interact with each other in an $S$ wave. This $S$-wave interaction will make such kind of meson loops always enhanced and can explain experimental observations of threshold enhancements. We show that the production of the $Y(4260)$ and the recently observed $Z_c(3900)$ can be related to each other by this mechanism which will allow for a possible understanding of the nature of these threshold enhancements.

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Qian Wang, Christoph Hanhart, Qiang Zhao. 2013-11-11. Meson loop singularity, exotic states' productions and decays near threshold. https://arxiv.org/abs/1311.2401

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