Predicting the $\bar{D}_s^{(*)} D_s^{(*)}$ bound states as the partners of $X(3872)$.
TL;DR: In this article, the SU(3) flavor symmetry, heavy quark spin symmetry and their breaking effects in the di-meson systems were investigated and the existence of the bound states was proved.
Abstract: In this work, we investigate the SU(3) flavor symmetry, heavy quark spin symmetry and their breaking effects in the di-meson systems. We prove the existence of the $[\bar{D}_{s}^{*}D_{s}^{*}]^{0^{++}}$, $[\bar{D}_{s}^{*}D_{s}/\bar{D}_{s}^{}D_{s}^*]^{1^{+-}}$, and $[\bar{D}_{s}^{*}D_{s}^{*}]^{1^{+-}}$ bound states as the consequence of two prerequisites in the SU(3) flavor symmetry and heavy quark spin symmetry. The first prerequisite, the $X(3872)$ as the weakly $\bar{D}^{*}D/\bar{D} D^{*}$ bound state is supported by its mass and decay branching ratios. The second prerequisite, the existence of the $[\bar{D}_{s}D_{s}]^{0^{++}}$ bound state is supported by the lattice QCD calculation [arXiv:2011.02542(hep-lat)] and the observation of $\chi_{c0}(3930)$ by the LHCb Collaboration[Phys.Rev.Lett.125,242001, Phys.Rev.D102,112003]. We hope the future experimental analyses can search for these bound states in the $B\to D_{(s)}^{(*)}\bar{D}^{(*)}_{(s)}h$ processes ($h$ denotes the light hadrons). The $[\bar{D}_{s}^{*}D_{s}^{*}]^{0^{++}}$ bound state is also expected to be reconstructed in the $J/\psi \phi$ final state in the $B\to J/\psi \phi K$ decay.
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TL;DR: In this paper, the authors investigated the kinetically allowed strong and radiative decay width in the single channel limit and isospin singlet limit of the tetraquark state.
Abstract: Very recently, the LHCb Collaboration reported the doubly charmed tetraquark state ${T}_{cc}^{+}$ below the ${D}^{*+}{D}^{0}$ threshold about 273 keV. As a very near-threshold state, its long-distance structure is very important. In the molecular scheme, we relate the coupling constants of ${T}_{cc}^{+}$ with ${D}^{*0}{D}^{+}$ and ${D}^{*+}{D}^{0}$ to its binding energy and mixing angle of two components with a coupled-channel effective field theory. With the coupling constants, we investigate the kinetically allowed strong decays ${T}_{cc}^{+}\ensuremath{\rightarrow}{D}^{0}{D}^{0}{\ensuremath{\pi}}^{+}$, ${T}_{cc}^{+}\ensuremath{\rightarrow}{D}^{+}{D}^{0}{\ensuremath{\pi}}^{0}$ and radiative decays ${D}^{+}{D}^{0}\ensuremath{\gamma}$. Our results show that the decay width of ${T}_{cc}^{+}\ensuremath{\rightarrow}{D}^{0}{D}^{0}{\ensuremath{\pi}}^{+}$ is the largest one, which is just the experimental observation channel. Our theoretical total strong and radiative widths are in favor of the ${T}_{cc}^{+}$ as a $|{D}^{*+}{D}^{0}⟩$ dominated bound state. The total strong and radiative width in the single channel limit and isospin singlet limit are given as ${59.7}_{\ensuremath{-}4.4}^{+4.6}\text{ }\text{ }\mathrm{keV}$ and ${46.7}_{\ensuremath{-}2.9}^{+2.7}\text{ }\text{ }\mathrm{keV}$, respectively. Our calculation is cutoff-independent and without prior isospin assignment. The absolute partial widths and ratios of the different decay channels can be used to test the structure of ${T}_{cc}^{+}$ state when the updated experimental results are available.
41 citations
TL;DR: In this paper, the authors performed a systematical investigation about the possible hidden and doubly heavy molecular states with open and hidden strangeness from interactions of a quasipotential Bethe-Salpeter equation approach.
Abstract: In this work, we perform a systematical investigation about the possible hidden and doubly heavy molecular states with open and hidden strangeness from interactions of $D^{(*)}{\bar{D}}^{(*)}_{s}$/$B^{(*)}{\bar{B}}^{(*)}_{s}$, ${D}^{(*)}_{s}{\bar{D}}^{(*)}_{s}$/${B}^{(*)}_{s}{\bar{B}}^{(*)}_{s}$, ${D}^{(*)}D_{s}^{(*)}$/${B}^{(*)}B_{s}^{(*)}$, and $D_{s}^{(*)}D_{s}^{(*)}$/$B_{s}^{(*)}B_{s}^{(*)}$ in a quasipotential Bethe-Salpeter equation approach. The interactions of the systems considered are described within the one-boson-exchange model, which includes exchanges of light mesons and $J/\psi/\Upsilon$ meson. Possible molecular states are searched for as poles of scattering amplitudes of the interactions considered. The results suggest that recently observed $Z_{cs}(3985)$ can be assigned as a molecular state of $D^*\bar{D}_s+D\bar{D}^*_s$, which is a partner of $Z_c(3900)$ state as a $D\bar{D}^*$ molecular state. The calculation also favors the existence of hidden heavy states $D_s\bar{D}_s/B_s\bar{B}_s$ with spin parity $J^P=0^+$, $D_s\bar{D}^*_s/B_s\bar{B}^*_s$ with $1^{+}$, and $D^*_s\bar{D}^*_s/B^*_s\bar{B}^*_s$ with $0^+$, $1^+$, and $2^+$. In the doubly heavy sector, the bound states can be found from the interactions $(D^*D_s+DD^*_s)/(B^*B_s+BB^*_s)$ with $1^+$, $D_s\bar{D}_s^*/B_s\bar{B}_s^*$ with $1^+$, $D^*D^*_s/B^*B^*_s$ with $1^+$ and $2^+$, and $D^*_sD^*_s/B^*_sB^*_s$ with $1^+$ and $2^+$. Some other interactions are also found attractive, but may be not strong enough to produce a bound state. The results in this work are helpful for understanding the $Z_{cs}(3985)$, and future experimental search for the new molecular states.
24 citations
TL;DR: In this paper, the authors extend the dynamical diquark model to encompass such states, using the same values of Hamiltonian parameters previously obtained from the nonstrange and hidden-strange sectors.
Abstract: The observation by BESIII and LHCb of states with hidden charm and open strangeness ($c\overline{c}q\overline{s}$) presents new opportunities for the development of a global model of heavy-quark exotics. Here we extend the dynamical diquark model to encompass such states, using the same values of Hamiltonian parameters previously obtained from the nonstrange and hidden-strange sectors. The large mass splitting between ${Z}_{cs}(4000)$ and ${Z}_{cs}(4220)$ suggests substantial ${\mathrm{SU}(3)}_{\text{flavor}}$ mixing between all ${J}^{P}={1}^{+}$ states, while their average mass compared to that of other sectors offers a direct probe of flavor octet-singlet mixing among exotics. We also explore the inclusion of $\ensuremath{\eta}$-like exchanges within the states, and find their effects to be quite limited. In addition, using the same diquark-mass parameters, we find ${P}_{c}(4312)$ and ${P}_{cs}(4459)$ to fit well as corresponding nonstrange and open-strange pentaquarks.
24 citations
TL;DR: In this paper, the implications of the hidden charm tetraquark states Z cs ( 3985 ) and Z cs( 4000 ) with strangeness were observed by the BESIII and LHCb collaborations, respectively, which are great breakthroughs for exploring exotic quantum chromodynamics structures.
Abstract: Recently, the hidden charm tetraquark states Z cs ( 3985 ) and Z cs ( 4000 ) with strangeness were observed by the BESIII and LHCb collaborations, respectively, which are great breakthroughs for exploring exotic quantum chromodynamics (QCD) structures. The first and foremost question is whether they are the same state. In this work, we explore the implications of the narrower state Z cs ( 3985 ) in BESIII and the wider one Z cs ( 4000 ) in LHCb as two different states. Within a solvable nonrelativistic effective field theory, we include the possible violations of heavy quark spin symmetry and SU(3) flavor symmetry in a comprehensive approach. If Z cs ( 3985 ) and Z cs ( 4000 ) are two different states, our results show that Z cs ( 4000 ) / Z cs ( 3985 ) is the pure ( | D ‾ s ∗ D 〉 + / - | D ‾ s D ∗ 〉 ) / 2 state, and the SU(3) flavor partner of Z c ( 3900 ) is Z cs ( 4000 ) rather than the Z cs ( 3985 ) . Another two important consequences are the existence of a tensor D ‾ s ∗ D ∗ resonance with mass about 4126 MeV and width 13 MeV, and the suppression of the decay mode Z cs ( 3985 ) → J / ψ K . The two consequences can be tested in experiments and distinguish the two-state interpretation from the one-state scheme.
19 citations
TL;DR: In this article, the authors revisited the isospin violating decays of $X(3872)$ in a coupled-channel effective field theory and showed that the proportion of the neutral channel in the decays is over 80%.
Abstract: In this work, we revisit the isospin violating decays of $X(3872)$ in a coupled-channel effective field theory. In the molecular scheme, the $X(3872)$ is interpreted as the bound state of ${\overline{D}}^{*0}{D}^{0}/{\overline{D}}^{0}{D}^{*0}$ and ${D}^{*\ensuremath{-}}{D}^{+}/{D}^{\ensuremath{-}}{D}^{*+}$ channels. In a cutoff-independent formalism, we relate the coupling constants of $X(3872)$ with the two channels to the molecular wave function. The isospin violating decays of $X(3872)$ are obtained by two equivalent approaches, which amend some deficiencies about this issue in literature. In the quantum field theory approach, the isospin violating decays arise from the coupling constants of $X(3872)$ to two dimeson channels. In the quantum mechanics approach, the isospin violating is attributed to wave functions at the origin. We illustrate that how to cure the insufficient results in literature. Within the comprehensive analysis, we bridge the isospin violating decays of $X(3872)$ to its inner structure. Our results show that the proportion of the neutral channel in $X(3872)$ is over 80%. As a by-product, we calculate the strong decay width of $X(3872)\ensuremath{\rightarrow}{\overline{D}}^{0}{D}^{0}{\ensuremath{\pi}}^{0}$ and radiative one $X(3872)\ensuremath{\rightarrow}{\overline{D}}^{0}{D}^{0}\ensuremath{\gamma}$. The strong decay width and radiative decay width are about 30 keV and 10 keV, respectively, for the binding energy from $\ensuremath{-}300\text{ }\text{ }\mathrm{keV}$ to $\ensuremath{-}50\text{ }\text{ }\mathrm{keV}$.
14 citations
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01 Aug 2020
3,138 citations
TL;DR: In this article, a narrow charmonium-like state produced in the exclusive decay process B+/--->K+/-pi(+)pi(-)J/psi has been observed, which has a mass of 3872.0+/-0.6(stat)+/- 0.5(syst) MeV.
Abstract: We report the observation of a narrow charmoniumlike state produced in the exclusive decay process B+/--->K+/-pi(+)pi(-)J/psi. This state, which decays into pi(+)pi(-)J/psi, has a mass of 3872.0+/-0.6(stat)+/-0.5(syst) MeV, a value that is very near the M(D0)+M(D(*0)) mass threshold. The results are based on an analysis of 152M B-Bmacr; events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The signal has a statistical significance that is in excess of 10sigma.
1,294 citations
TL;DR: Recently, the LHCb Collaboration discovered two hidden-charm pentaquark states, which are also beyond the quark model as discussed by the authors, and investigated various theoretical interpretations of these candidates of the multiquark states.
1,083 citations