Lattice predictions for bound heavy tetraquarks

Anthony Francis*, Renwick J. Hudspith, Randy Lewis, Kim Maltman


研究成果: Conference article同行評審


We investigate the possibility of doubly heavy qq′Q¯Q¯′ tetraquark bound states using nf = 2+1 lattice QCD with pion masses ≃ 164, 299 and 415 MeV. Two types of lattice interpolating operator are chosen, reflecting first diquark-antidiquark and second meson-meson structure. Performing variational analyses using these operators and their mixings, we determine the ground and first excited states from the lattice correlators. Using non-relativistic QCD to simulate the bottom quarks and the Tsukuba formulation of relativistic heavy quarks for charm quarks, we study the udb¯b¯, ℓsb¯b¯ as well as udc¯b¯, channels with ℓ = u,d. In the case of the udb¯b¯ and ℓsb¯b¯ channels unambiguous signals for JP = 1+ tetraquarks are found with binding energies 189(10) and 98(7) MeV below the corresponding free two-meson thresholds at the physical point. These tetraquarks are therefore not only strong-interaction, but also electromagnetic-interaction stable, and can decay only weakly. So far these are the first exotic hadrons predicted to have this feature. Further evidence for binding is found in the udc¯b¯ channel, where the binding energy broadly straddles the electromagnetic stability threshold. We also study the dependence of the tetraquark binding on heavy quark mass by considering the channels udb¯′b¯′, ℓsb¯′b¯′ as well as udb¯′b¯, ℓsb¯′b¯ involving a heavy b′ quark with mass between roughly 0.6 and 6.3 times the physical b quark mass. The observed mass dependence of these four flavor channels is shown to follow closely a phenomenological form expected on simple physical grounds.

期刊Proceedings of Science
出版狀態Published - 2019
事件39th International Conference on High Energy Physics, ICHEP 2018 - Seoul, Korea, Republic of
持續時間: 4 7月 201811 7月 2018


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