Production rates of $D_{s}^{+}D_{s}^{-}$ and $D\bar{D}$ molecules in $B$ decays

Abstract

Motivated by the recent discovery of a charmonium X(3960) in B decays by the LHCb Collaboration, the likely existence of two bound/virtual states (denoted by X ss and X q q ) below the D + s D − s and DD mass thresholds has been re-examined recently. In this work, we employ the effective Lagrangian approach to calculate their production rates in B decays utilizing triangle diagrams. Our results show that the production yields of B + → X ss K + and *

Analysis of the exotic resonances in the systems $QQ\bar q\bar q$ and $Qq\bar Q\bar q$ with the extended recoupling model

“…In the literature exotic four-quark resonances have been considered using different mechanisms, including standard coupled channel method [8], the tetraquark model within the Born-Oppenheimer approach [9,10,11,12], the cusp phenomenon and the triangle singularity [13,14,15], the few-body theory of hadron-hadron interaction [16], analytic approach including the boson exchange mechanism [17,18,19,20], and the QCD sum rule method [21]. In the present paper we formulate the model of the hadron-hadron interaction with the resonance creation as an extended version of the recoupling approach [7], which explains the hadron-hadron resonances as the poles from the infinite sum of the recoupling diagrams, where the hadrons pass through the stage of the compound bag, producing the string recoupling between hadrons.…”

Connection between near the $D_s^+D_s^-$ threshold enhancement in $B^+ \to D_s^+D_s^-K^+$ and conventional charmonium $χ_{c0}(2P)$

“…For understanding this novel phenomenon, some theoretical explanations were proposed. The X(3960) was explained as a threshold structure due to the D s Ds interaction, where the interpretation of a virtual or bound state below the D + s D − s threshold [2,3], and the D + s D − s molecule description from the QCD sum rules method [4] and the one-boson-exchange model [5] were proposed. In Ref.…”

“…After introducing the D * (3 3 S 1 ) resonant contribution, the shoulder-like shape in the D − s K + invariant mass distribution from 3.0 to 3.2 GeV can be well depicted. Moreover, the interference between the background term and the reflection contribution of the D * (3 3…”

“…When depicting the whole D + s D − s invariant mass spectrum, the contributions from higher charmonium ψ(4230) and charmoniumlike state X 0 (4140) are obvious. In addition, a charmed meson D * (3 3 S 1 ) with mass around 3015 MeV is found to be important to depict the D − s K + invariant mass spectrum well. Especially, the importance of node effect of the spatial wave function of the χ c0 (2P) is revealed, by which the anomaly of the ratio Γ(X → D + D − )/Γ(X → D + s D − s ) indicated by LHCb can be explained well.…”

“…2 The mass gap between the χ c0 (3930) ≡ χ c0 (2P) and the D + s D − s threshold is 12 ± 2 MeV and the measured width of χ c0 (3930) is 17.4 ± 5.1 ± 0.8 MeV [7]. 3 The node effect of the coupling g χ c0 (2P)D + s D − s is obvious if taking β < 0.5 GeV, which is deviated from the β value fixed by the unquenched quark model [24].…”