Productions of $X(3872)$, $Z_c(3900)$, $X_2(4013)$, and $Z_c(4020)$ in $B_{(s)}$ decays offer strong clues on their molecular nature

Abstract

The exotic states $X(3872)$ and $Z_c(3900)$ have long been conjectured as isoscalar and isovector ${\bar{D}}^{\ast }D$ molecules. In this work, we first propose the triangle diagram mechanism to investigate their productions in $B$ decays as well as their heavy quark spin symmetry partners, $X_2(4013)$ and $Z_c(4020)$. We show that the large isospin breaking of the ratio $\mathcal{B}[B^{+}\to X(3872)K^{+}]/\mathcal{B}[B^0\to X(3872)K^0]$ can be attributed to the isospin breaking of the neutral and charged ${\bar{D}}^{\ast }D$ components in their wave functions. For the same reason, the branching fractions of $Z_c(3900)$ in $B$ decays are smaller than the corresponding ones of $X(3872)$ by at least one order of magnitude, which naturally explains its non-observation. A hierarchy for the production fractions of $X(3872)$, $Z_c(3900)$, $X_2(4013)$, and $Z_c(4020)$ in $B$ decays, consistent with all existing data, is predicted. Furthermore, with the factorization ansatz we extract the decay constants of $X(3872)$, $Z_c(3900)$, and $Z_c(4020)$ as ${\bar{D}}^{\ast }{D}^{(\ast )}$ molecules via the $B$ decays, and then calculate their branching fractions in the relevant $B_{(s)}$ decays, which turn out to agree with all existing experimental data. The mechanism we proposed is useful to elucidate the internal structure of the many exotic hadrons discovered so far and to extract the decay constants of hadronic molecules,which can be used to predict their production in related processes.

References in corpus (18)

• Emergence of a complete heavy-quark spin symmetry multiplet: seven molecular pentaquarks in light of the latest LHCb analysis
• The Heavy Quark Spin Symmetry Partners of the X(3872)
• Is X(3872) {\sl Really} a Molecular State?
• Isospin breaking effects in the X(3872) resonance
• $Z_b$ and $Z_c$ Exotic States as Coupled Channel Cusps
• QCD Sum Rules for the X(3872) as a mixed molecule-charmoniun state
• The study of $B_c^{-}\to X(3872){\pi }^{-}(K^{-})$ Decays in the Covariant Light-Front Approach
• Detecting the long-distance structure of the X(3872)
• Analysis of the hidden-charm tetraquark molecule mass spectrum with the QCD sum rules
• $D^{\ast }{D}_{s}K$ and $D_s^{\ast }DK$ vertices in a QCD Sum Rule approach
• A Phenomenological analysis on isospin-violating decay of $X(3872)$
• $F_K/F_{\pi }$ from Möbius domain-wall fermions solved on gradient-flowed HISQ ensembles
• Heavy-hadron molecules from light-meson-exchange saturation
• QCD Sum Rules for the production of the X(3872) as a mixed molecule-charmonium state in B meson decay
• Is $Z_{cs}(3982)$ a molecular partner of $Z_c(3900)$ and $Z_c(4020)$ states?
• Charmed and $\varphi$ meson decay constants from 2+1-flavor lattice QCD
• SU(4) flavor symmetry breaking in D-meson couplings to light hadrons
• Search for hidden-charm pentaquark states in three-body final states

Cited by in corpus (7)

• Production of the $X(4014)$ as the spin-2 partner of $X(3872)$ in $e^{+}{e}^{-}$ collisions
• $P$-wave charmonium contribution to hidden-charm states from reanalysis of lattice QCD data
• Productions of $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ in $B_{(s)}$ and ${\Lambda }_b({\Xi }_b)$ decays
• ${\bar{B}}^0\to {\bar{K}}^{(\ast )0}X$, $B^{-}\to K^{(\ast )-}X$, ${\bar{B}}_s^0\to \eta ({\eta }^{\prime },\varphi )X$ from the $X(3872)$ molecular perspective
• Strong decays of the isovector-scalar $D^{\ast }{\bar{D}}^{\ast }$ hadronic molecule
• The $B^{-}\to J/\psi {\eta }^{\prime }{K}^{-}$ reaction and the $Y(4710)$ and $K_0^{\ast }(1430)$ contributions
• Production of the $X(3872)$ state via the $B^0\to K^{\ast 0}X(3872)$ decay