LAUSR

The threshold behavior of e+e− annihilation is considered in the channels Bs0B̄ ∗ s + c.c., Bs1B̄s+ c.c., and Bs1B̄ ∗ s + c.c., where Bs0 and Bs1 are the excited bottom-strange JP = 0+ and JP = 1+ mesons. It is argued that due to the heavy quark spin symmetry (HQSS) only one coherent combination of the first two channels is produced in the S wave as well as the third channel. Thus, if there exist threshold molecular peaks in the considered channels, only two of such peaks can be formed in the annihilation. The properties of such threshold states are discussed, including the heavy-light spin structure and the related transitions to bottomonium plus light mesons, as well as mixing with the channels with and without hidden strangeness. The structures with hidden heavy flavor produced in the ee annihilation near the thresholds for heavy meson pairs are of a well known great interest for the studies of those mesons [e.g. D mesons at ψ(3770), or B mesons at Υ(4S)] as well as for exploring the strong interaction between the heavy hadrons that results in an intricate sequence of peaks and dips in the yield of specific final channels. The bulk of the data available thus far mostly relates to the production of pairs of two ground state mesons, i.e. the pairs DD̄ in the charm sector, or BB̄ in the beauty sector, with a possible addition of a pion, and significantly less is known about the excited heavy mesons, especially in the beauty sector. In particular, the strange excited Bs0 and Bs1 mesons with quantum numbers J P = 0 and J = 1 are not yet observed, and their expected properties are predicted [1, 2, 3] by extrapolation from those of their charm counterpartsDs0(2317) andDs1(2460). It has been recently argued [4] that the strange excited B mesons can be studied in the ee annihilation in the Belle II experiment at energies near the thresholds for the channels Bs0B̄ ∗ s + c.c., Bs1B̄s + c.c., and Bs1B̄ ∗ s + c.c., which thresholds are expected to be at approximately 11.1GeV for the first two final states and about 48MeV higher for the third one. The purpose of the present paper is to elaborate in some detail on the properties of the J = 1 states of this type produced in the ee annihilation. In particular, it will be argued, based on HQSS, that only one superposition of the C-odd states Bs0B̄ ∗ s − c.c., Bs1B̄s − c.c. is being produced, and that the heavy-light spin structure of this superposition and of the higher state Bs1B̄ ∗ s − c.c. is, to an extent, analogous to that in the Zb(10610 and Zb(10650) resonances [5] (albeit in the sector with opposite parity), resulting in a comparable rate of hadronic transitions to levels of orthoand para-bottomonium. Furthermore, it will be argued that the rescattering of the considered states to pairs of the ground-state mesons, both with and without hidden strangeness, is vanishing in the heavy quark limit, so that the yield of the Bs0 and Bs1 mesons should be more prominent than that for their charmed counterparts in the charmonium-like sector at 4.4 4.55GeV. In what follows is presented a brief overview of the orbitally excited heavy mesons and their possible production in the ee annihilation with a subsequent discussion of the heavy-light spin structure of the produced states and of rescattering between the channels. Specific numerical estimates, based on the heavy quark expansion and the data on the charmed mesons, as well as recently acquired (and still scarce) data on excited nonstrange B mesons, is postponed till later in the paper, where also discussed are possible (dis)similarities with the observed behavior in the charmonium-like energy region. As is well known, the ground-state heavy-light mesons form a doublet consisting of a pseudoscalar and a vector meson, e.g. B and B, with the mass splitting inversely propor-