More on heavy tetraquarks in lattice QCD at almost physical pion mass

We report on our progress in studying exotic, heavy tetraquark states, qq′ Q̄ Q̄ ′. Using publicly available dynamical n_f = 2 + 1 Wilson-Clover gauge configurations, generated by the PACS-CS collaboration, with pion masses ? 164, 299 and 415 MeV, we extend our previous analysis to heavy quark components containing heavier than physical bottom quarks Q̄ Q̄ ′ = b̄ ′b̄ ′ or Q̄ Q̄ ′ = b̄ b̄ ′, charm and bottom quarks c̄ b̄ and also only charm quarks c̄ c̄. Throughout we employ NRQCD and relativistic heavy quarks for the heavier than bottom, bottom and charm quarks. Using our previously established diquark-antidiquark and meson-meson operator basis we comment in particular on the dependence of the binding energy on the mass of the heavy quark component Q̄ Q̄, with heavy quarks ranging from m_Q = 0:85. 6.3 · m_b. In the heavy flavor non-degenerate case, Q̄ Q̄ ′, and especially for the tetraquark channel udc̄ d̄, we extend our work to utilize a 3 × 3 GEVP to study the ground and threshold states thereby enabling a clear identification of possible binding. Finally, we present initial work on the Q̄ Q̄ ′ = c̄ c̄ system where a much larger operator basis is available in comparison to flavor combinations with NRQCD quarks.