Task 2.2 - Computation of heavy-quark, hybrid and tetraquark potentials


    Coordinator: Antonio Vairo



    General description:


    The long-term aim of this subtask is to compute on the lattice the relativistic corrections to the heavy quark potential, and hybrid and tetraquark potentials as defined in the non-relativistic effective field theories pNRQCD and BOEFT using unquenched lattice QCD.



    Progress [1-18 months]:


    There has been noteworthy progress in heavy Quarkonium spectroscopy with the computation on unquenched lattices (2+1 flavors) of the excited and exotic bottomonium spectrum (including hybrids) in [Ry20] This has been the first fully relativistic and unquenched lattice calculation in the bottomonium sector.

    Related to this calculation is the study of QCD thermodynamics with 2+1 flavors of Wilson fermions of [Aa20]. It sets the groundwork for further studies of spectroscopy, including for heavy quarks.

    At the same time there is significant progress going on in:

    • extending the calculation of the heavy quark potentials to 2+1+1 flavors capturing the charm mass dependence,

    • studying mesons in NRQCD in order to understand their thermal masses and width shifts,

    •  studying the interquark potential using NRQCD quarks to understand thermal variations.

    We finally mention an extensive review that includes conventional and exotic quarkonium spectroscopy, theoretical and experimental is in [Br20g].


    The spin-identified spectrum of bottomonium mesons, labelled by JPC  from [Ry20].




    • [Ry20] S. M. Ryan et al. [Hadron Spectrum coll.], "Excited and exotic bottomonium spectroscopy from lattice QCD", arXiv:2008.02656 [hep-lat].
    • [Aa20] G. Aarts, C. Allton, J. Glesaaen, S. Hands, B. Jäger, S. Kim, M. P. Lombardo, A. A. Nikolaev, S. M. Ryan, J. I. Skullerud and L. K. Wu, "Properties of the QCD thermal transition with Nf=2+1 flavours of Wilson quark", arXiv:2007.04188 [hep-lat].
    • [Br20g] N. Brambilla, S. Eidelman, C. Hanhart, A. Nefediev, C. P. Shen, C. E. Thomas, A. Vairo and C. Z. Yuan, "The XYZ states: experimental and theoretical status and perspectives", Phys. Rept. 873 (2020), 1-154.


    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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