Both unitary chiral theories and lattice QCD simulations show that the $DK$ interaction is attractive and can form a bound state, namely, $D^*_{s0}(2317)$. Assuming the validity of the heavy antiquark-diquark symmetry (HADS), the $Ξ_{cc}\bar{K}$ interaction is the same as the $DK$ interaction, which implies the existence of a $Ξ_{cc}\bar{K}$ bound state with a binding energy of $49-64$ MeV. In this work, we study whether a $Ξ_{cc}Ξ_{cc}\bar{K}$ three-body system binds. The $Ξ_{cc}Ξ_{cc}$ interaction is described by exchanging $π$, $σ$, $ρ$, and $ω$ mesons, with the corresponding couplings related to those of the $NN$ interaction via the quark model. We indeed find a $Ξ_{cc}Ξ_{cc}\bar{K}$ bound state, with quantum numbers $J^P=0^-$, $I=\frac{1}{2}$, $S=1$ and $C=4$, and a binding energy of $80-118$ MeV. It is interesting to note that this system is very similar to the well-known $NN\bar{K}$ system, which has been studied extensively both theoretically and experimentally. Within the same framework, we show the existence of a $NN\bar{K}$ state with a binding energy of $35-43$ MeV, consistent with the results of other theoretical works and experimental data, which serves as a consistency check on the predicted $Ξ_{cc}Ξ_{cc}\bar{K}$ bound state.
The mass, decay constant and width of a hypothetical charmed partner $X_c$ of the newly observed exotic $X_b(5568)$ state are calculated using a technique of QCD sum rule method. The $X_c=[su][\overline{c}\overline{d}]$ state with $J^{P}=0^{+}$ is described employing two types of the diquark-antidiquark interpolating currents. The evaluation of the mass $m_{X_c}$ and decay constant $f_{X_c}$ is carried out utilizing the two-point sum rule method by including vacuum condensates up to eight dimensions. The widths of the decay channels $X_c \to D_s^{-} π^{+}$ and $X_c \to D^{0} K^{0}$ are also fo…
The recent observation by the D$Ø$ collaboration of the first tetraquark candidate with four different quark flavors $(u, d, s$ and $ b)$ in the $B^0_sπ^{\pm}$ channel having a narrow structure, has still not been confirmed by other collaborations. Further independent experiments are required either to confirm the $X(5568)$ state or to set limits on its production. Though quantum numbers are not exactly clear, the results existing in the literature indicate that it is probably an axial-vector or scalar state candidate. In this study, mass and pole residue of the $X(5568)$ resonance assuming as…
New resonance $Λ_c(2860)^+$, reported by LHCb, is a key to establish \emph{D}-wave charmed and charmed-strange baryon families. In this work, we first carry out an analysis of mass spectra of the $λ$-mode excited charmed and charmed-strange baryon states, which may reveal the relation of $Λ_c(2860)^+$, $Λ_c(2880)^+$, $Ξ_c(3055)^+$ and $Ξ_c(3080)^+$, $i.e.$, $Λ_c(2860)^+$ and $Λ_c(2880)^+$ can form a \emph{D}-wave doublet $[3/2^+,5/2^+]$ while $Ξ_c(3055)^+$ and $Ξ_c(3080)^+$ are the strange partners of $Λ_c(2860)^+$ and $Λ_c(2880)^+$, respectively. Further study of their two-body Okubo-Zweig-Ii…
Using the effective Lagrangian approach, we examine the recently observed charm states $D^{*}_{J}(2460)$, $D_{J}(2560)$, $D_{J}(2740)$, $D_{J}(3000)$ and their spin partners $D^{*}_{J}(2680)$, $D^{*}_{J}(2760)$ and $D^{*}_{J}(3000)$ with $J^{P}$ states $1P_{\frac{3}{2}}2^{+}$, $2S_{\frac{1}{2}}0^{-}$, $1D_{\frac{5}{2}}2^{-}$, $2P_{\frac{1}{2}}1^{+}$ and $2S_{\frac{1}{2}}1^{-}$, $1D_{\frac{5}{2}}3^{-}$, $2P_{\frac{1}{2}}0^{+}$ respectively. We study their two body strong decays, coupling constants and branching ratios with the emission of light pseudo-scalar mesons $(π, η, K)$. We also analyze …
Chiral thermodynamics of charmed mesons is formulated at finite temperature within a $2+1+1$-flavored effective Lagrangian incorporating heavy quark symmetry. The charmed-meson mean fields act as an extra source which breaks the chiral symmetry explicitly. This leads to effective interactions between the light and heavy-light mesons, which intrinsically depend on temperature. Effective masses of the scalar and pseudoscalar charmed-mesons tend to approach each other as increasing temperature, so that the splitting between the chiral partners is reduced. These chiral splittings are shown to be l…
Inspired by the newly observed $D^{(*)}(3000)$, and $D_{sJ}(3040)$ states, in this work we study the production of $D^{(*)}(3000)$, $D_{sJ}(3040)$ and their partners through the semileptonic decays of $B_{(s)}$ mesons, where the light-front Quark model is applied to the whole calculation. Our numerical results indicate that the $B_{(s)}$ semileptonic decays into the $2P$ states of the charmed or charmed-strange meson family have considerable branching ratios, which shows that these semileptonic decays can be accessible at future experiments, especially LHCb and the forthcoming Belle II.
In this work, we systematically study the interaction of $D^*$ and nucleon, which is stimulated by the observation of $Λ_c(2940)^+$ close to the threshold of $D^*p$. Our numerical result obtained by the dynamical investigation indicates the existence of the $D^*N$ systems with $J^P=1/2^\pm,\,3/2^\pm$, which not only provides valuable information to understand the underlying structure of $Λ_c(2940)^+$ but also improves our knowledge of the interaction of $D^*$ and nucleon. Additionally, the bottom partners of the $D^*N$ systems are predicted, which might be as one of the tasks in LHCb experimen…
We study the $D$-wave charmed baryons of $SU(3)$ flavor $\mathbf{\bar3}_F$ using the method of QCD sum rule in the framework of heavy quark effective theory (HQET). We find that the $Λ_c(2880)$, $Ξ_c(3055)$ and $Ξ_c(3080)$ can be well described by the $D$-wave $SU(3)$ $\mathbf{\bar 3}_F$ charmed baryon multiplets of $J^P=3/2^+$ and $5/2^+$, which contain two $λ$-mode orbital excitations, i.e., the $Λ_c(2880)$ has $J^P=5/2^+$, and the $Ξ_c(3055)$ and $Ξ_c(3080)$ have $J^P = 3/2^+$ and $5/2^+$, respectively. Our results also suggest that the $Λ_c(2880)$ has a partner state, the $Λ_c(3/2^+)$ of $…
We remind the chiral doubling scenario [1,2] for hadrons built of heavy and light quarks. Then we recall arguments why new states D_s(2317),D_s(2460),D_0(2308) and D_1^'(2427) should be viewed as chiral partners of D_s,D_s^*,D and D^*,respectively. We summarize with the list of predictions based on chiral doubling scenario for other heavy-light hadrons.
It is pointed out that assigning D_{s0}^+(2317) to an iso-triplet tetra-quark meson is favored by experiments. It also is discussed why its neutral and doubly charged partners have never been observed in inclusive e^+e^- annihilation. To search for them, hadronic weak decays of B mesons would be better, and their production rates, Br(B_u^+ -> D^-D_{s0}^{++}(2317)) and Br(B_d^0 ->antiD^0D_{s0}^{0}(2317)), would be around 10^{-3}.
We explore the consequences of heavy quark spin symmetry for the charmed meson-antimeson system in a contact-range (or pionless) effective field theory. As a trivial consequence, we theorize the existence of a heavy quark spin symmetry partner of the X(3872), with $J^{PC}=2^{++}$, which we call X(4012) in reference to its predicted mass. If we additionally assume that the X(3915) is a $0^{++}$ heavy spin symmetry partner of the X(3872), we end up predicting a total of six $D^{(*)}\bar{D}^{(*)}$ molecular states. We also discuss the error induced by higher order effects such as finite heavy qua…
Hadron spectroscopy provides direct physical measurements that shed light on the non-perturbative behavior of quantum chromodynamics (QCD). In particular, various exotic hadrons such as the newly observed $T_{cc}^+$ by the LHCb collaboration, offer unique insights on the QCD dynamics in hadron structures. In this letter, we demonstrate how heavy ion collisions can serve as a powerful venue for hadron spectroscopy study of doubly charmed exotic hadrons by virtue of the extremely charm-rich environment created in such collisions. The yields of $T_{cc}^+$ as well as its potential isospin partners…
We study the P-wave charmed baryons using the method of QCD sum rule in the framework of heavy quark effective theory (HQET). We consider systematically all possible baryon currents with a derivative for internal rho- and lambda-mode excitations. We have found a good working window for the currents corresponding to the rho-mode excitations for Lambda_c(2595), Lambda_c(2625), Xi_c(2790) and Xi_c(2815) which complete two SU(3) 3F_bar multiplets of J(P)=1/2(-) and 3/2(-), while the currents corresponding to the lambda-mode excitations seem also consistent with the data. Our results also suggest t…
The charmoniumlike state $Y(4260)$ is described as predominantly a $D_1 \bar{D}$ molecule in a coupled-channel quark model [Phys.\,Rev.\,D\,\textbf{96},\,114022\,(2017)]. The heavy quark spin symmetry (HQSS) thus implies the possible emergence of its heavy quark spin partners with molecular configuration as $D_1 \bar{D}^*$ and $D_2^* \bar{D}^*$ below these charmed mesons' thresholds. We analyze the probabilities of various intermediate charmed meson loops for $J^{PC}=1^{--}$ exotic state $Y(4360)$ and find that the channel $D_1 \bar{D}^*$ couples more strongly around its mass regime, and the c…
We adopt the heavy baryon chiral perturbation theory (HBChPT) to calculate the scattering lengths of $ϕB_{cc}^{(*)}$ up to $\mathcal{O}(p^3)$, where $ϕ$ is the pseudoscalar mesons. The recoil effect and the mass splitting between the spin-$1\over 2$ and spin-$3\over 2$ doubly charmed baryons are included. In order to give the numerical results, we construct the chiral Lagrangians with heavy diquark-antiquark (HDA) symmetry in a formally covariant approach. Then, we relate the low energy constants (LECs) of the doubly charmed baryons to those of $D^{(*)}$ mesons. The LECs for the $ϕD^{(*)}$ sca…
Newly observed two charmed-strange resonances, $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, are investigated by calculating their Okubo-Zweig-Iizuka allowed strong decays, which shows that they are suitable candidates for the $1^3D_1$ and $1^3D_3$ states in the charmed-strange meson family. Our study also predicts other main decay modes of $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, which can be accessible at the future experiment. In addition, the decay behaviors of the spin partners of $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, i.e., $1D(2^-)$ and $1D^\prime(2^-)$, are predicted in this work, which are sti…
In this work, an Effective Field Theory (EFT) incorporating light SU(3)-flavour and heavy quark spin symmetry is used to describe charmed meson-antimeson bound states. At Lowest Order (LO), this means that only contact range interactions among the heavy meson and antimeson fields are involved. Besides, the isospin violating decays of the X(3872) will be used to constrain the interaction between the $D$ and a $\bar{D}^*$ mesons in the isovector channel. Finally, assuming that the X(3915) and Y(4140) resonances are $D^*\bar{D}^*$ and $D_s^*\bar{D}_s^*$ molecular states, we can determine the four…
The pentaquark states, $P_{c}(4312)$, $P_{c}(4440)$ and $P_{c}(4450)$, can be nicely arranged into a multiplet of seven molecules of $\bar{D}^{(\ast)}Σ_{c}^{(\ast)}$ dictated by heavy quark spin symmetry, while the $Ξ_{cc}^{(\ast)}Σ_{c}^{(\ast)}$ system can be related to the $\bar{D}^{(\ast)}Σ_{c}^{(\ast)}$ system via heavy antiquark diquark symmetry. In this work we employ the one boson exchange model to study the interactions between $Ξ_{cc}^{(\ast)}$ and $Σ_{c}^{(\ast)}$ with constraints from the pentaquark system. We show that a multiplet of ten triply charmed dibaryons emerge naturally in…
The LHCb collaboration has recently observed three narrow pentaquark states --- the $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$ ---that are located close to the $\bar{D} Σ_c$ and $\bar{D}^* Σ_c$ thresholds. Among the so-far proposed theoretical interpretations for these pentaquarks, the molecular hypothesis seems to be the preferred one. Nevertheless, in the molecular picture the spins of the $P_c(4440)$ and $P_c(4457)$ have not been unambiguously determined yet. In this letter we point out that heavy antiquark-diquark symmetry induces a model-independent relation between the spin-splitting in t…
We study the quark structure of the sigma meson through the decay of $D_1(2430)$ meson by constructing an effective Lagrangian for charmed mesons interacting with light mesons based on the chiral symmetry and heavy quark symmetry. Within the linear realization of the chiral symmetry, we include the P-wave charmed mesons ($D_1(2430)$, $D_0(2400)$) as the chiral partners of ($D^\ast$, $D$), and the light scalar mesons as the chiral partner of the pseudoscalar mesons. In the light meson sector, both the $q\bar{q}$ and $qq\bar{q}\bar{q}$ states are incorporated respecting their different U(1)$_A$ …
In this paper, we assume $X(5568)$ exist and study mass spectrum of $X(5568)$ resonance and its hypothetical charmed partner, $X_c$, by Artificial Neural Network method. The obtained predictions are compared with the experimental data and results of other theoretical works.
Inspired by $P_c(4380)$ and $P_c(4450)$ recently observed by LHCb, a QCD sum rule investigation is performed, by which they can be identified as exotic hidden-charm pentaquarks composed of an anti-charmed meson and a charmed baryon. Our results suggest that $P_c(4380)$ and $P_c(4450)$ have quantum numbers $J^P=3/2^-$ and $5/2^+$, respectively. Furthermore, two extra hidden-charm pentaqurks with configurations $\bar{D}Σ_c^*$ and $\bar{D}^*Σ_c^*$ are predicted, which have spin-parity quantum numbers $J^P=3/2^-$ and $J^P=5/2^+$, respectively. As an important extension, the mass predictions of hid…
Heavy-quark symmetry as applied to heavy hadron systems implies that their interactions are independent of their heavy-quark spin (heavy-quark spin symmetry) and heavy flavour contents (heavy flavour symmetry). In the molecular hypothesis the $X(3872)$ resonance is a $1^{++}$ $D^*\bar{D}$ bound state. If this is the case, the application of heavy-quark symmetry to a molecular $X(3872)$ suggests the existence of a series of partner states, the most obvious of which is a possible $2^{++}$ $D^*\bar{D}^*$ bound state for which the two-body potential is identical to that of the $1^{++}$ $D^*\bar{D}…
The charmed meson pair $(\frac{3}{2})^+$ and anti-$(\frac{1}{2})^-$, i.e. $D_1(2420)\bar D+c.c.$, $D_1(2420)\bar D^*+c.c.$, $D_2(2460)\bar D^*+c.c.$, can couple to states with vector quantum number $J^{PC}=1^{--}$ and exotic quantum number $J^{PC}=1^{-+}$ in a relative $S$ wave. Near threshold, the charmed meson pair may form hadronic molecules due to the strong $S$-wave coupling, and the mysterious vector state $Y(4260)$ could be such a state of the $D_1(2420)\bar D+c.c.$ molecule. This implies the possible existence of its exotic partner made of the same charmed mesons but with $J^{PC}=1^{-+…
The doubly charmed $Ξ_{cc}^{++} (ccu)$ state is the only listed baryon in PDG, which was discovered in the experiment. The LHCb collaboration gets closer to discovering the second doubly charmed baryon $Ξ_{cc}^{+} (ccd)$, hence the investigation of the doubly charmed/bottom baryons from many aspects is of great importance that may help us not only get valuable knowledge on the nature of the newly discovered states, but also in the search for other members of the doubly heavy baryons predicted by the quark model. In this context, we investigate the strong coupling constants among the $Ξ_{cc}^{+…
We study the hadronic molecular structure of hidden heavy pentaquarks - new exotic states composed of charmed/bottom baryons and $D(D^*)/B(B^*)$ mesons. Based on the observation of three pentaquark candidates $P_c^+(4312)$, $P_c^+(4440)$, and $P_c^+(4457)$ by the LHCb Collaboration we consider the classification of possible flavor partners composed of charmed baryons and $D(D^*)$ mesons within the hadronic molecular approach. We extend this classification to the bottom sector. Using phenomenological Lagrangians we construct baryon-meson bound states governed by the Weinberg-Salam compositeness…
Recently five $Ω_c$ excited states have been reported by the LHCb Collaboration, four of them corroborated by Belle. The Belle Collaboration has also discovered in 2017 one excited $Ξ_c$ with mass of 2930 MeV. In view of these recent detections, we analyze the possible molecular description of these states, using a unitarized baryon-meson model that incorporates both chiral and heavy-quark spin symmetries in a consistent manner. We pay a special attention to the renormalization procedure, so as to determine the robustness of our predictions. Within our model, we generate dynamically several $Ω…
We discuss the consequences of the chiral doubling scenario for baryons built of heavy and light quarks. In particular, we use the soliton description for baryons, demonstrating why each heavy-light baryon should be accompanied by the opposite parity partner. Our argumentation holds both for ordinary baryons and for exotic heavy pentaquarks which are required by the symmetries of QCD to appear in parity doublets, seperated by the mass shift of the chiral origin. Interpreting the recently observed by BaBaR, CLEO and Belle charmed mesons with assignment $(0^+,1^+)$ as the chiral partners of know…
We study the structure of the $Λ_c(2595)$ and $Λ_c(2625)$ resonances in the framework of an effective field theory consistent with heavy quark spin and chiral symmetries, that incorporates the interplay between $Σ_c^{(*)}π-ND^{(*)}$ baryon-meson degrees of freedom and bare P-wave $c\bar ud$ quark-model states. We show that these two resonances are not HQSS partners. The $J^P= 3/2^-$ $Λ_c(2625)$ should be viewed mostly as a dressed three quark state, whose origin is determined by a bare state, predicted to lie very close to the mass of the resonance. The $J^P= 1/2^-$ $Λ_c(2595)$ seems to have, …
The hadronic decay widths and some ratios of branching fractions of the newly observed charmed strange baryons, $Ξ_c(3055)^0$, $Ξ_c(3055)^+$ and $Ξ_c(3080)^+$ are calculated in a $^3P_0$ model. In the calculation, they are considered as $34$ kinds of $D-wave$ charmed strange baryons. Among these assignments, $Ξ_c(3055)^+$ is very possibly a $J^P={5\over 2}^+$ $\hatΞ_{c3}^\prime(\frac{5}{2}^+)$ or $\checkΞ_{c3}^2(\frac{5}{2}^+)$, where $Ξ_c(3055)^+$ has the total decay width $Γ=10.1$ MeV and $Γ=7.6$ MeV. The predicted ratios $Γ(Ξ_c(3055)^+ \to ΛD^+ )/ Γ(Ξ_c(3055)^+ \to Σ_c^{++}K^-)=3.39$. $Ξ_c(…
We study the $Ξ_b(6100)$ using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the $Ξ_b(6100)$ can be well interpreted as the $P$-wave bottom baryon of $J^P=3/2^-$, belonging to the $SU(3)$ flavor $\mathbf{\bar 3}_F$ representation. It has a partner state of $J^P=1/2^-$, labelled as $Ξ_b(1/2^-)$, whose mass and width are predicted to be $m_{Ξ_b(1/2^-)}=6.08^{+0.13}_{-0.11}$~GeV and $Γ_{Ξ_b(1/2^-)}=4^{+29}_{-~4}$~MeV, with the mass splitting $ΔM=m_{Ξ_b(6100)}-m_{Ξ_b(1/2^-)}=9\pm3$~MeV. We propose to search for …
We report on some properties of the newly observed charged hidden-charmed open strange $ Z_{cs}(3985)^- $ state by BESIII Collaboration. Assigning the quantum numbers $ J^{P} = 1^{+}$ and the quark composition $ c \bar c s\bar u $ and considering it as the strange partner of the famous $ Z_c(3900) $ state, we estimate the mass of the $ Z_{cs}(3985)^- $ resonance in vacuum and compare it with the experimental data. We also investigate its mass, current coupling and vector-self energy in a medium with finite density. Our result on the mass in vacuum agrees well with the experimental data. We est…
The $D^{(\ast)}Ξ_{cc}^{(\ast)}$ system and $\barΞ_{cc}^{(\ast)}Ξ_{cc}^{(\ast)}$ system can be related to the $D^{(\ast)}\bar{D}^{(\ast)}$ system via heavy anti-quark di-quark symmetry (HADS). In this work, we employ a contact-range effective field theory to systematically investigate the likely existence of molecules in these systems in terms of the hypothesis that X(3872) is a $1^{++}$~$D\bar{D}^{\ast}$ bound state in the isospin symmetry limit, with some of the unknown low energy constants estimated using the light-meson saturation approximation. In the meson-meson system, a $J^{PC}=2^{++}$~…
We propose an effective field theory incorporating light SU(3)-flavour and heavy quark spin symmetry to describe charmed meson-antimeson bound states. At lowest order the effective field theory entails a remarkable simplification: it only involves contact range interactions among the heavy meson and antimeson fields. We show that the isospin violating decays of the X(3872) can be used to constraint the interaction between the $D$ and a $\bar{D}^*$ mesons in the isovector channel. As a consequence, we can rule out the existence of a isovector partner of the X(3872). If we additionally assume th…
We investigate the recent evidence for a charged $X(5568)$ meson as an exotic open-flavor tetraquark state $su\bar b\bar d$ with $J^P=0^+/1^+$ in the framework of QCD sum rules. We use the color antisymmetric $[\mathbf{\bar 3_c}]_{su} \otimes [\mathbf{3_c}]_{\bar{b}\bar d}$ tetraquark currents in both scalar and axial-vector channels to perform evaluations and numerical analyses. Our results imply that the $X(5568)$ can be interpreted as both the scalar $su\bar b\bar d$ tetraquark state and the axial-vector one, which are in good agreement with the experimental measurement. We also discuss the…
The bottom-charmed ($B_c$) mesons are more stable than their charmonium ($c\bar c$) and bottomium ($b\bar b$) partners because they cannot annihilate into gluons. However, the low production cross-sections and signal-to-background ratios avoided until now their clear identification. The recent experimental results reported by CMS and LHCb at CERN open the possibility of having a $B_c$ spectrum as complete as the ones of charmonium and bottomonium. Motivated by this expectation, we compute bottom-charmed meson masses in the region energies in which decay meson-meson thresholds are opened, looki…
Chiral partners of strange doubly heavy baryons: Mass relations and decay predictions after the 2026 LHCb discoveries
Institute of Theoretical Physics and Mark Kac Center for Complex Systems Research, Jagiellonian University（雅盖隆大学理论物理研究所与马克·卡克复杂系统研究中心）；Center for Nuclear Theory, Department of Physics and Astronomy, Stony Brook University（石溪大学物理与天文学系核心理论中心）
We use the method of QCD sum rules to study the $D$-wave charmed and bottom baryons of the $SU(3)$ flavor $\mathbf{6}_F$, and calculate their masses up to the order $\mathcal{O}(1/m_Q)$ with $m_Q$ the heavy quark mass. Our results suggest that the $Ξ_c(3123)$ can be well interpreted as a $D$-wave $Ξ_c^\prime(\mathbf{6}_F)$ state, and it probably has a partner state close to it. Our results also suggest that there may exist as many as four $D$-wave $Ω_c$ states in the energy region $3.3\sim3.5$ GeV, and we propose to search for them in the further LHCb and BelleII experiments.
The spectrum of hadronic molecules composed of heavy-antiheavy charmed hadrons has been obtained in our previous work. The potentials are constants at the leading order, which are estimated from resonance saturation. The experimental candidates of hadronic molecules, say $X(3872)$, $Y(4260)$, three $P_c$ states and $P_{cs}(4459)$, fit the spectrum well. The success in describing the pattern of heavy-antiheavy hadronic molecules stimulates us to give more predictions for the heavy-heavy cases, which are less discussed in literature than the heavy-antiheavy ones. Given that the heavy-antiheavy h…
Starting from an effective Lagrangian with heavy quark spin symmetry embedded, the coupled-channel dynamics of the doubly charmed systems $D^{(*)} Σ_c^{(*)}$ is investigated. The potential underlying our investigation includes $t$-channel pseudoscalar and vector meson exchanges. A series of $S$-wave bound states with isospin $I=1/2$ is found by applying the first iterated solution of the $N/D$ method: one state with binding energy $23$ MeV in the $5/2^-$ $D^*Σ_c^*$ channel, three states with binding energy $26$, $30$ and $7$ MeV (relative to the thresholds from low to high, respectively) in th…
The heavy hadron spectrum is constrained by symmetries, of which two of the most important ones are heavy-quark spin and SU(3)-flavor symmetries. Here we argue that in the molecular picture the $Y(4230)$ (or $Y(4260)$), the $Y(4360)$ and the recently discovered $Y(4500)$ and $Y(4620)$ vector-like resonances are linked by these two symmetries. By formulating a contact-range effective field theory for the $D \bar{D}_1$ and $D_s \bar{D}_{s1}$ family of S- and P-wave charmed meson-antimeson systems, we find that if the $Y(4230)$ were to be a pure $D \bar{D}_1$ molecular state, there would be a $D^…
The $S$-wave eigenstates of tetraquarks of type $s u \bar d \bar b$ with J$^{P}$ = 0$^{+}$, 1$^{+}$ and 2$^{+}$ are studied within a simple quark model with chromomagnetic interaction and effective quark masses extracted from meson and baryon spectra. It is tempting to see if this spectrum can accommodate the new narrow structure X(5568), observed by the DØ~~Collaboration, but not confirmed by the LHCb Collaboration. If it exists, such a tetraquark is a system with four different flavors and its study can improve our understanding of multiquark systems. The presently calculated mass of X(5568)…
The discovery of the $D^\ast_{s0}(2317)$ and $D_{s1}(2460)$ resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between $Q\bar q$ and $(Q\bar q)(q\bar q)$ Fock components. In contrast to the $c\bar s$ sector, there is no experimental evidence of $J^P=0^+,1^+$ bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the $D_{s0}…
