Project Details
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Hot Heavy Mesons

Applicant Professor Dr. Dirk H. Rischke, since 8/2020
Subject Area Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
Term from 2018 to 2022
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 411563442
 
Final Report Year 2022

Final Report Abstract

With this research project the properties of mesons made of heavy quarks have been studied in a bath of mesons with light degrees of freedom. The starting point is an effective theory that incorporates the most relevant scales and symmetries of Quantum Chromodynamics (QCD). The results extracted from this study can be summarized as follows. First, the properties of mesons with charm quarks in a bath made of light mesons at temperatures below the QCD phase transition have been studied by determining the scattering amplitudes and, hence, spectral functions at finite temperature based on a unitarized effective hadronic theory at finite temperature, fully consistent with chiral and heavy-quark symmetries, which are two QCD symmetries present in the low and high mass quark limits, respectively. Second, the experimentally observed X(3872) state, its spin partner, the X(4014), and associated excited bottom states have been analyzed in matter, so as to understand whether these states can be understood as molecular states that are generated dynamically by the scattering of a heavy meson with a heavy antimeson. It has been found that all these states can be dynamically generated while showing a decreasing mass and acquiring an increasing decay width with temperature, following the trend observed in their meson constituents. These results are relevant in relativistic heavy-ion collisions at high energies, in analyses of the collective medium formed after hadronization or in femtoscopic studies, and can be tested in lattice QCD calculations exploring the melting of heavy mesons at finite temperature. Third, the drag and diffusion coefficients of the mesons previously studied have been calculated and tested against data from heavy-ion collisions and lattice QCD simulations near the QCD phase transition region. It has been determined that the spatial diffusion coefficient matches smoothly to the latest results of lattice QCD calculations and Bayesian analyses at higher temperatures. And, finally, the Euclidean temporal correlators of those heavy mesons for temperatures below the QCD phase transition have been addressed for the first time, by means of calculating the spectral functions implementing the quark-mass dependence on the hadron masses, so as to compare them with recent lattice QCD results. As a result, it is observed that Euclidean correlators show a similar behavior as the one obtained in lattice QCD for temperatures well below the QCD transition temperature, being the discrepancies at larger temperatures due to missing states.

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