In this work, we study the isospin conserved hidden bottomonium decay of $X_b\to Υ(1S)ω$, where $X_b$ is taken to be the counterpart of the famous $X(3872)$ in the bottomonium sector as a candidate for the meson-meson molecule. Since it is likely that the $X_b$ is below the $B\bar B^*$ threshold and the mass difference between the neutral and charged bottom meson is small compared to the binding energy of the $X_b$, the isospin violating decay mode $X_b\to Υ(nS)π^+π^-$ would be greatly suppressed. We use the effective Lagrangian based on the heavy quark symmetry to explore the rescattering mechanism of $X_b\to Υ(1S)ω$ and calculate the partial widths. Our results show that the partial width for the $X_b\to Υ(1S)ω$ is about tens of keVs. Taking into account the fact that the total width of $X_b$ may be smaller than a few MeV like $X(3872)$, the calculated branching ratios may reach to orders of $10^{-2}$. These hidden bottomonium decay modes are of great importance in the experimental search for the $X_b$ particularly at the hadron collider. Also, the associated studies of hidden bottomonium decays $X_b \to Υ(nS) γ$, $Υ(nS)ω$, and $B\bar B γ$ may help us investigate the structure of $X_b$ deeply. The experimental observation of $X_b$ will provide us with further insight into the spectroscopy of exotic states and is helpful to probe the structure of the states connected by the heavy quark symmetry.
In the present work, we investigate the productions of the molecular states composed of $D^{(*)}_s \bar{D}^{(*)}$ and $D^{(*)}_s \bar{D}^{(*)}_s$ in the $B$ and $B_s$ decays by using an effective Lagrangian approach. The branching ratios in terms of the model parameter $α$ and the binding energy $ΔE$ are estimated. Our estimations indicate that the branching fractions are of the order of $10^{-4}$ and the relative ratios are very weakly dependent on the model parameter $α$ and the binding energy $ΔE$. The predicted ratios are helpful for searching the hidden-charm molecular states with strange…
We explore constraints on gauge bosons of a weakly coupled $U(1)_{B-L}$, $U(1)_{L_μ-L_e}$, $U(1)_{L_e-L_τ}$ and $U(1)_{L_μ-L_τ}$. To do so we apply the full constraining power of experimental bounds derived for a hidden photon of a secluded $U(1)_{X}$ and translate them to the considered gauge groups. In contrast to the secluded hidden photon that acquires universal couplings to charged Standard Model particles through kinetic mixing with the photon, for these gauge groups the couplings to the different Standard Model particles can vary widely. We take finite, computable loop-induced kinetic m…
We study baryo-charmonium [$η_{\rm c}$- and $J/ψ$-$N^*$, $η_{\rm c}(2S)$-, $ψ(2S)$- and $χ_{\rm c}(1P)$-$N$] and baryo-bottomonium [$η_{\rm b}(2S)$-, $Υ(2S)$- and $χ_{\rm b}(1P)$-$N$] bound states, where $N$ is the nucleon and $N^*$ a nucleon resonance. In the baryo-quarkonium model, the five $qqq Q \bar Q$ quarks are arranged in terms of a heavy quarkonium core, $Q \bar Q$, embedded in light baryonic matter, $qqq$, with $q = u$ or $d$. The interaction between the $Q \bar Q$ core and the light baryon can be written in terms of the QCD multipole expansion. The spectrum of baryo-charmonium state…
The discovery of a charged strange hidden-charm state $Z_{cs}$(3985) implies another higher $Z^*_{cs}$ state coupling to $\bar{D}_s^{*-}D^{*0} + c.c$ under the heavy quark spin symmetry. In this paper we discuss a possible hunt for it with data taken at existing facilities. We point out a hint for $Z^*_{cs}$ in the data of $\bar{B}_s^0 \to J/ψK^- K^+$ at LHCb, though weak, in line with the production mechanism of pentaquark $P_c$. We also study the triangular singularity which would possibly enhance the production of $Z^*_{cs}$ in electron-positron collision. Surprisingly, the production rate …
We study the $Υ(1S)$ meson photoproduction on protons and nuclei at the near-threshold center-of-mass energies below 11.4 GeV (or at the corresponding photon laboratory energies $E_γ$ below 68.8 GeV). We calculate the absolute excitation functions for the non-resonant and resonant photoproduction of $Υ(1S)$ mesons off protons at incident photon laboratory energies of 63--68 GeV by accounting for direct ($γp \to {Υ(1S)}p$) and two-step ($γp \to P^+_b(11080,11125,11130) \to {Υ(1S)}p$) $Υ(1S)$ production channels within different scenarios for the non-resonant total cross section of elementary re…
The lightest hidden-bottom tetraquarks in the dynamical diquark model fill an $S$-wave multiplet consisting of 12 isomultiplets. We predict their masses and dominant bottomonium decay channels using a simple 3-parameter Hamiltonian that captures the core fine-structure features of the model, including isospin dependence. The only experimental inputs needed are the corresponding observables for $Z_b(10610)$ and $Z_b(10650)$. The mass of $X_b$, the bottom analogue to $X(3872)$, is highly constrained in this scheme. In addition, using lattice-calculated potentials we predict the location of the c…
In this work, we propose the $4S$-$3D$ mixing scheme to assign the $Υ(10753)$ into the conventional bottomonium family. Under this interpretation, we further study its hidden-bottom hadronic decays with a $η^{(\prime)}$ or $ω$ emission, which include $Υ(10753)\toΥ(1S)η^{(\prime)}$, $Υ(10753)\to h_{b}(1P)η$ and $Υ(10753)\toχ_{bJ}ω$ ($J$=0,1,2) processes. Since the $Υ(10753)$ is above the $B\bar{B}$ threshold, the coupled-channel effect cannot be ignored, thus, when calculating partial decay widths of these $Υ(10753)$ hidden-bottom decays, we apply the hadronic loop mechanism. Our result shows t…
We study the mass splittings of $Q_1q_2\bar{Q}_3\bar{q}_4$ ($Q=c,b$, $q=u,d,s$) tetraquark states with chromomagnetic interactions between their quark components. Assuming that $X(4140)$ is the lowest $J^{PC}=1^{++}$ $cs\bar{c}\bar{s}$ tetraquark, we estimate the masses of the other tetraquark states. From the obtained masses and defined measure reflecting effective quark interactions, we find the following assignments for several exotic states: (1) both $X(3860)$ and the newly observed $Z_c(4100)$ seem to be $0^{++}$ $cn\bar{c}\bar{n}$ tetraquarks; (2) $Z_c(4200)$ is probably a $1^{+-}$ $cn\b…
我们分别研究了与传统的$c\bar{c}$粲偶素和$b\bar{b}$底偶素解释相悖的奇异态的光谱。2003年8月，发现了X（3872）态[K. Abe \textit{\ et al.}（Belle Collaboration），物理学评论快报。\textbf{91}，262001（2003）[arXiv：hep-ex/0309032]]，并且在2007年12月报道了状态Y（10890）[K. F. Chen \textit{et. al.} [Belle协作]，Phys. Rev. Lett. \textbf{100}，112001（2008）[arXiv：0710.2577]。对这种奇异态的一种可能解释是它们是四夸克（双夸克-反夸克）态。应用非相对论组分夸克模型的知识，在双夸克-反双夸克模型下计算了隐魅介子和底奇异介子的能谱。我们研究了X（3872）是$X_{[cq]}=([cq]_{S=1}[ \bar{c}\bar{q}]_{S=0})_{S\mathrm{-wave}}$类的$1^{++}$态，Y（10890）是$Y_{[bq]}=([bq]_{S=0}[\bar{b}\bar{q}]_{S=0})_{\mathrm{P-wave}}$类的$1^{--}$态，并计算了这两种奇异态的衰变模式，进一步支持了X（3872）和Y（10890）是四夸克（双夸克-反双夸克）态，解决…
The properties of the $B_c$-meson family ($c\bar b$) are still not well determined experimentally because the specific mechanisms of formation and decay remain poorly understood. Unlike heavy quarkonia, i.e. the hidden heavy quark-antiquark sectors of charmonium ($c\bar c$) and bottomonium ($b\bar b$), the $B_c$-mesons cannot annihilate into gluons and they are, consequently, more stable. The excited $B_c$ states, lying below the lowest strong-decay $BD$-threshold, can only undergo through radiative decays and hadronic transitions to the $B_c$ ground state, which then decays weakly. As a resul…
