Open charm-bottom scalar tetraquarks and their strong decays

Abstract

The mass and meson-current coupling of the diquark-antidiquark states with the quantum numbers J P = 0 + and quark contents Zq = [cq] [bq] and Zs = [cs][bs] are calculated using two-point QCD sum rule approach. In calculations the quark, gluon and mixing condensates up to eight dimensions are taken into account. The parameters of the scalar tetraquarks extracted from this analysis are employed to explore the strong vertices ZqBcπ, ZqBcη and ZsBcη and compute the couplings gZ q Bcπ , gZ q Bcη and gZ sBc η . The strong couplings are obtained within the soft-meson approximation of QCD light-cone sum rule method: they form, alongside with other parameters, the basis for evaluating the widths of Zq → Bcπ, Zq → Bcη and Zs → Bcη decays. Obtained in this work results for the mass of the tetraquarks Zq and Zs are compared with available predictions presented in the literature.

New a1(1420) state: Structure, mass, and width

“…[33,35]. The LCSR method and soft approximation were adapted to study vertices involving a tetraquark and conventional mesons in our work [34], and was later applied to investigate decays of various tetraquarks [36][37][38][39][40].…”

Analysis of $X(4140)$ like states and their radial excitations in QCD

“…Among these studies, most of them predicted the masses consistent with experimantal results, however only two of them successfully estimated both the mass and the quantum numbers of X (4140) consistent with experiments [7,20]. For the X (4274), there are only two studies [20,21] and their results are good agreement with the LHCb. In which authors threated X (4274) as an axial vector ground state.…”

“…In theory, there are several studies investigating the internal structure of X (4140) and X (4274), by using different quantum numbers in the tetraquark scheme [7,8,9,10,11,12,13,14,15,16,17,18,19,20]. Among these studies, most of them predicted the masses consistent with experimantal results, however only two of them successfully estimated both the mass and the quantum numbers of X (4140) consistent with experiments [7,20]. For the X (4274), there are only two studies [20,21] and their results are good agreement with the LHCb.…”

Spectroscopic parameters and decays of the resonance $$Z_b(10610)$$ Z b ( 10610 )

“…The current with the same quantum numbers but different color organization may also play a role of such alternative (see, for example, Ref. [44]). One of the possible scenarios implies that the observed resonances are admixtures of these tetraquarks, which may fit measured decay widths.…”

“…The mathematical methods to handle the soft-meson limit were elaborated in Refs. [40,41] and were successfully applied to tetraquark vertices in our previous articles [42][43][44][45]. In the soft limit p = p and the relevant invariant amplitudes in the correlation function depend only on one variable: p 2 .…”