Highlights - October 2020


    Despite the Coronavirus pandemic, members of the JRA7-HaSp WP25 initiated a productive collaboration. Experimentalists working tin the world-leading nuclear physics facilities and theorists start to work together to run experiments, collect data, set an analysis framework and provide a sound interpretation to reveal the basic mechanisms of hadronic interaction.

    On the experimental side, high-precision data are being accumulated at Jefferson Lab for the study of glueballs and hybrids. Analysis frameworks are using novel techniques like machine learning for particle identification and large scale computing, data preservation goes along with partial wave analyses which provides synergy with theory, data mining and new analyses are performed in a world-wide collaborative effort, involving the main EU laboratories (CERN, Mainz, Bonn, GSI) and abroad (TJNAF/US, BESIII/China, J-PARC/Japan, Belle/Japan). Unexpected exotic hadron resonances, including tetraquarks, molecules and hadrons with explicit gluonic degree of freedom have been found both in the light and heavy quark sector (eg. XYZ ststes). Baryon spectroscopy is producing new results in the strange-quark and hexotic di-baryon sector:  the recent Mainz experiment with polarized photons indicate the existence of a possible compact hexaquark configuration. 

    In the previous HadronPhysics integrated activities, connections between a large number of theorists were established, thanks to  which many aspects of light and heavy quark hadronic physics were successfully investigated. This activity has been boosted by the unexpected wealth of data from hadronic physics facilities worldwide mentioned above, and to which the theoretical and experimental members of our WP have contributed significantly.  On the theoretical side, we have used QCD symmetries at the hadron or quark levels to construct EFT's,  in some occasions combined with analyticity and dispersive properties, which have allowed us to provide systematic and theoretically founded descriptions of some of the exotic hadron resonances and regular quark-model states reported by experiments. The diverse theoretical scenarios, emerging from these studies, have been tested against existing event-distributions and data for electromagnetic, weak and strong decays. We have obtained in this way also further support for theorized new states, as for instance, the light SU(3) partners of the LHCb pentaquarks.  We have also examined decays involving new physics beyond the Standard Model in connection with the persisting experimental LFU violations.  We also note important progresses on the study of the modification of the hadron and heavy-quark properties when embedded in hot environments, on the study of neutron matter calculations using as input nucleon-nucleon chiral-EFT interactions, and on the study of nuclear responses.  We should also highlight, competitive determinations of the strong coupling constant using LQD and experimental data, and a significant progress in heavy Quarkonium spectroscopy with the computation on unquenched lattices of the excited and exotic bottomonium spectrum (including hybrids).

    This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 824093.

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