Triangle singularities waning in Heavy Ion Collisions: the case of Y(4260)→ π(πJ/ψ)

2021/09/02 by Abreu, Luciano M., Llanes-Estrada, Felipe J.
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2109.01015

Abstract

We have recently observed that hadron triangle singularities, that can mock new exotic hadrons, can be significanttly suppressed in relativistic heavy ion collisions, provided two conditions are met: these are, first, that the fireball lives long enough so that the triangle process has enough time to complete in the Norton-Coleman classical sense, and second, that the mass and/or width of the particles in the triangle diagram are sufficiently modified from their vacuum values. Here we add a very interesting example to the canon, which is Y(4260) → D₁ D → πD^* D → π+ J/ψπ. This reaction has been proposed as a mechanism to explain the appearance of Z_c(3900) in the J/ψπ spectrum. If the two muons and two pions reconstructing the initial-state Y can be isolated from the combinatorial background, then the mechanism can provide a spectroscopy test: presence of Y(4260) but absence of Z_c(3900) would be more indicative of such triangle mechanism, while presence of both would rather point out to Z_c being an exotic hadron.

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