Spin structure of heavy-quark hybrids
Brambilla, Nora (Technische Universität München. Institute for Advanced Study)
Lai, Wai Kin (Technische Universität München. Physik Department)
Segovia, Jorge (Universitat Autònoma de Barcelona. Departament de Física)
Tarrús Castellà, Jaume (Institut de Física d'Altes Energies)
Vairo, Antonio (Technische Universität München. Physik Department)

Data:	2019
Resum:	A unique feature of quantum chromodynamics (QCD), the theory of strong interactions, is the possibility for gluonic degrees of freedom to participate in the construction of physical hadrons, which are color singlets, in an analogous manner to valence quarks. Hadrons with no valence quarks are called glueballs, while hadrons where both gluons and valence quarks combine to form a color singlet are called hybrids. The unambiguous identification of such states among the experimental hadron spectrum has been thus far not possible. Glueballs are particularly difficult to establish experimentally since the lowest lying ones are expected to strongly mix with conventional mesons. On the other hand, hybrids should be easier to single out because the set of quantum numbers available to their lowest excitations may be exotic, i. e. , not realized in conventional quark-antiquark systems. Particularly promising for discovery appear to be heavy hybrids, which are made of gluons and a heavy-quark-antiquark pair (charm or bottom). In the heavy-quark sector systematic tools can be used that are not available in the light-quark sector. In this paper we use a nonrelativistic effective field theory to uncover for the first time the full spin structure of heavy-quark hybrids up to 1/m2-terms in the heavy-quark-mass expansion. We show that such terms display novel characteristics at variance with our consolidated experience on the fine and hyperfine splittings in atomic, molecular and nuclear physics. We determine the nonperturbative contributions to the matching coefficients of the effective field theory by fitting our results to lattice-QCD determinations of the charmonium hybrid spectrum and extrapolate the results to the bottomonium hybrid sector where lattice-QCD determinations are still challenging.
Ajuts:	European Commission 665919 Ministerio de Economía y Competitividad FPA2014-55613-P Ministerio de Economía y Competitividad FPA2017-86989-P Ministerio de Economía y Competitividad SEV-2016-0588 Ministerio de Economía y Competitividad IJCI-2016-30028
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Nuclear physics ; Effective field theory ; Nonrelativistic QCD ; Quantum chromodynamics
Publicat a:	Physical Review D, Vol. 99, issue 1 (Jan. 2019) , art. 14017, ISSN 2470-0029

DOI: 10.1103/PhysRevD.99.014017

11 p, 311.7 KB

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