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Register a new userPhotoproduction of strange hidden-charm and hidden-bottom states
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Recently BESIII collaboration discovered a charged strange hidden-charm state $Z_{cs}$(3985) in the $D_s^-D^{*0} + D_s^{*-}D^{0}$ spectrum. A higher $Z_{cs}$ state coupling to $bar{D}_s^{*-}D^{*0}$ is expected by SU(3)-flavor symmetry, and their bottom partners are anticipated by heavy quark flavor symmetry. Here we study the photoproduction of these exotic states and investigate carefully the background from Pomeron exchange. Our results indicate that the maximal photoproduction cross section of strange partner is around 1 $sim$ 2 orders of magnitude smaller than that of the corresponding non-strange states. The possibility of searching for them in future electron-ion colliders (EIC) is briefly discussed.
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We investigate heavy quark symmetries for heavy light meson-antimeson systems in a contact-range effective field theory. In the SU(3) light flavor limit, the leading order Lagrangian respecting heavy quark spin symmetry contains four independent counter-terms. Neglecting $1/m_Q$ corrections, three of these low energy constants can be determ1ined by theorizing a molecular description of the $X(3872)$ and $Z_b(10610)$ states. Thus, we can predict new hadronic molecules, in particular the isovector charmonium partners of the $Z_b(10610)$ and the $Z_b(10650)$ states. We also discuss hadron molecules composed of a heavy meson and a doubly-heavy baryon, which would be related to the heavy meson-antimeson molecules thanks to the heavy antiquark-diquark symmetry. Finally, we also study the $X(3872) to D^0bar D^0pi^0$ decay, which is not only sensitive to the short distance part of the $X(3872)$ molecular wave function, as the $J/psipipi$ and $J/psi3pi$ $X(3872)$ decay modes are, but it is also affected by the long-distance structure of the resonance. Furthermore, this decay might provide some information on the interaction between the $Dbar D$ charm mesons.
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 center of mass of the $P$-wave multiplet and find that $Y(10860)$ fits well but the newly discovered $Y(10750)$ does not, more plausibly being a $D$-wave bottomonium state. Using similar methods, we also examine the lowest $S$-wave multiplet of 6 $cbar c sbar s$ states, assuming as in earlier work that $X(3915)$ and $Y(4140)$ are members, and predict the masses and dominant charmonium decay modes of the other states. We again use lattice potentials to compute the centers of mass of higher multiplets, and find them to be compatible with the masses of $Y(4626)$ ($1P$) and $X(4700)$ ($2S$), respectively.
Due to the discovery of the hidden-charm pentaquark $P_c$ states by the LHCb collaboration, the interests on the candidates of hidden-bottom pentaquark $P_b$ states are increasing. They are anticipated to exist as the analogues of the $P_c$ states in the bottom sector and predicted by many models. We give an exploration of searching for a typical $P_b$ in the $gamma p to Upsilon p$ reaction, which shows a promising potential to observe it at an electron-ion collider. The possibility of searching for $P_b$ in open-bottom channels are also briefly discussed. Meanwhile, the $t$-channel non-resonant contribution, which in fact covers several interesting topics at low energies, is systematically investigated.
Recently, the LHCb Collaboration reported three $P_c$ states in the ${J/psi}p$ channel. We systematically study the mass spectrum of the hidden charm pentaquark in the framework of an extended chromomagnetic model. For the $nnncbar{c}$ pentaquark with $I=1/2$, we find that (i) the lowest state is $P_{c}(4327.0,1/2,1/2^{-})$ [We use $P_{c}(m,I,J^{P})$ to denote the $nnncbar{c}$ pentaquark], which corresponds to the $P_{c}(4312)$. Its dominant decay mode is $Lambda_{c}bar{D}^{*}$. (ii) We find two states in the vicinity of $P_{c}(4380)$. The first one is $P_{c}(4367.4,1/2,3/2^{-})$ and decays dominantly to $N{J/psi}$ and $Lambda_{c}bar{D}^{*}$. The other one is $P_{c}(4372.4,1/2,1/2^{-})$. Its dominant decay mode is $Lambda_{c}bar{D}$, and its partial decay width of $Neta_{c}$ channel is comparable to that of $N{J/psi}$. (iii) In higher mass region, we find $P_{c}(4476.3,1/2,3/2^{-})$ and $P_{c}(4480.9,1/2,1/2^{-})$, which correspond to $P_{c}(4440)$ and $P_{c}(4457)$. In the open charm channels, both of them decay dominantly to the $Lambda_{c}bar{D}^{*}$. (iv) We predict two states above $4.5~text{GeV}$, namely $P_{c}(4524.5,1/2,3/2^{-})$ and $P_{c}(4546.0,1/2,5/2^{-})$. The masses of the $nnncbar{c}$ state with $I=3/2$ are all over $4.6~text{GeV}$. Moreover, we use the model to explore the $nnscbar{c}$, $ssncbar{c}$ and $ssscbar{c}$ pentaquark states.
We have studied the meson-baryon $S-$wave interaction, using coupled channels, in the isoscalar hidden-charm strange sector and $J^P = 1/2^-,3/2^-$ and $5/2^-$. We impose constraints of heavy quark spin symmetry in the interaction and obtain the non vanishing matrix elements from an extension of the local hidden gauge approach to the charm sector. The ultraviolet divergences are renormalized using the same meson-baryon-loops regulator previously employed in the non-strange hidden charm sector, where a good reproduction of the properties of the newly discovered pentaquark states is obtained. We obtain five states of $1/2^-$, four of $3/2^-$ and one of $5/2^-$, which could be compared in the near future with forthcoming LHCb experiments. The $5/2^-$, three of the $3/2^-$ and another three of the $1/2^-$ resonances are originated from isoscalar $bar D^{(*)}Xi_c^prime$ and $bar D^{(*)}Xi_c^*$ interactions. They should be located just few MeV below the corresponding thresholds (4446, 4513, 4588 and 4655 MeV), and would be SU(3)-siblings of the isospin 1/2 $bar D^{(*)} Sigma_c^{(*)}$ quasi-bound states previously found, and that provided a robust theoretical description of the $P_c(4440)$, $P_c(4457)$ and $P_c(4312)$ LHCb exotic states. The another two $1/2^-$ and $3/2^-$ states obtained in this work are result of the $bar D^{(*)}Xi_c-D^{(*)}_sLambda_c$ coupled-channels isoscalar interaction, are significantly broader than the others, with widths of the order of 15 MeV, being $bar D^{(*)}_sLambda_c$ the dominant decay channel.
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