BBinteractions with static bottom quarks from lattice QCD

Abstract

The isospin, spin and parity dependent potential of a pair of B mesons is computed using Wilson twisted mass lattice QCD with two flavours of degenerate dynamical quarks. The B meson is addressed in the static-light approximation, i.e. the b quarks are infinitely heavy. From the results of the B B meson-meson potentials, a simple rule can be deduced stating which isospin, spin and parity combinations correspond to attractive and which to repulsive forces. We provide fits to the ground state potentials in the attractive channels and discuss the potentials in the repulsive and excited channels. The attractive channels are most important since they can possibly lead to a bound four-quark state, i.e. abbud tetraquark. Using these attractive potentials in the Schrödinger equation, we find indication for such a tetraquark state of two static bottom antiquarks and two light u/d quarks with mass extrapolated down to the physical value.

Heavy-hadron interactions from Lattice QCD

“…These results are shown in Figure 17. The binding energies at comparable quark mass agree roughly with the values presented in [61], both of which are much larger than the value obtained in the static limit in [59].…”

“…In Sections 4 and 5 exploratory results for exotic charmonia and doubly-heavy hadrons have been presented. Among these, evidence for the existence of doubly-heavy bound states with flavor content udbb and lsbb [59,61,63] is especially intriguing.…”

“…In [54,55] the authors studied doubly-charmed tetraquarks, while doublybottom four-quark states are studied in [56][57][58][59][60]. In this chapter I will highlight some of the newer results.…”

“…The authors of [59,60] In a first publication [59] the authors study the scalar isosinglet and vector isotriplet channels neglecting effects of the heavyb spin. Solving a non-relativistic Schrödinger equation, they find the vector isotriplet channel to be unbound, both at all three of the pion masses separately and in the limit of physical pion masses.…”

The hidden-charm pentaquark and tetraquark states

“…Especially the dimeson, dibaryon and pentaquark molecular systems with two charm/bottom quarks are particularly interesting, which have have been studied using various models [852,853,854,855,856,857], QCD sum rules [858,859] as well as the lattice QCD [860,861,862]. These hadrons may be produced either at LHC or through heavy ion collisions or through higher bottomonium decays.…”