We propose to search for the open heavy-flavor exotic states with the quark components of $Qs\bar u\bar d$ with $Q=b,c$ via their weak decays. If there exist such exotic states below the $BK$ or $DK$ thresholds, they can only decay weakly. The advantages include: (i) the experimental backgrounds from the secondary decay vertex are much lower due to the long lifetimes, (ii) the productions are large enough for only one heavy quark in such states, (iii) the thresholds of $BK$ or $DK$ are about 260 MeV higher compared to the $B_sπ$ or $D_sπ$ thresholds of the configurations of $Qu\bar s\bar d$ or $Qd\bar s\bar u$ , with a higher possibility to exist such weakly-decay particles, and (iv) if observed, their inner structures are easier understood since they can not be induced by the kinematic effects.
Motivated by the LHCb observation of exotic states $X_{0,1}(2900)$ with four open quark flavors in the $D^- K^+$ invariant mass distribution in the decay channel $B^\pm \to D^+ D^- K^\pm$, we study the spectrum and decay properties of the open charm tetraquarks. Using the two-body chromomagnetic interactions, we find that the two newly observed states can be interpreted as a radial excited tetraquark with $J^P=0^+$ and an orbitally excited tetraquark with $J^P=1^-$, respectively. We then explore the mass and decays of the other flavor-open tetraquarks made of $su \bar d \bar c$ and $ d s \bar …
The dynamical diquark model assumes that exotic hadrons can be formed from colored diquarks. This model asserts a multiquark exotic state composed of a compact diquark $δ$ and antidiquark $\barδ$ for a tetraquark interacting through a gluonic field of finite extent. Using Born-Oppenheimer (BO) approximation and BO potential calculated numerically on the lattice, we study mass spectra of $S-$wave $cc\bar{b}\bar{b}$, $bc\bar{c}\bar{c}$, and $bc\bar{b}\bar{b}$ tetraquark systems in the basis of diquark spins. We assume that colour-antitriple diquark and colour-triplet antidiquark form tetraquark …
Motivated by the Belle Collaboration's new observation of $Y(4626)$, we investigate the possibility of its configuration as a $P$-wave $[cs][\bar{c}\bar{s}]$ tetraquark state from QCD sum rules. Eventually, the extracted mass $4.60^{+0.13}_{-0.19}~\mbox{GeV}$ for the $P$-wave $cs$-scalar-diquark $\bar{c}\bar{s}$-scalar-antidiquark state agrees well with the experimental data of $Y(4626)$, which could support its interpretation as a $P$-wave scalar-scalar $[cs][\bar{c}\bar{s}]$ tetraquark state.
In this work we study the mass spectra of the fully-heavy tetraquark systems, i.e. $cc\bar{c}\bar{c}$, $bb\bar{b}\bar{b}$, $bb\bar{c}\bar{c}/cc\bar{b}\bar{b}$, $bc\bar{c}\bar{c}/cc\bar{b}\bar{c}$, $bc\bar{b}\bar{b}/bb\bar{b}\bar{c}$, and $bc\bar{b}\bar{c}$, within a potential model by including the linear confining potential, Coulomb potential, and spin-spin interactions. It shows that the linear confining potential has important contributions to the masses and is crucial for our understanding of the mass spectra of the fully-heavy tetraquark systems. For the fully-heavy tetraquarks $Q_1Q_2\ba…
In the heavy-quark limit, the two heavy quarks in a doubly heavy baryon or a doubly heavy tetraquark are bound by their color-Coulomb potential into a compact diquark. The doubly heavy hadrons are related by the approximate heavy-quark--diquark symmetry of QCD to the heavy hadrons obtained by replacing the heavy diquark by a heavy antiquark. Effective field theories can be used to expand the masses of singly heavy hadrons and doubly heavy hadrons in inverse powers of the heavy quark masses. The coefficients in the expansions for doubly heavy tetraquarks can be determined from those for heavy m…
We briefly review the stability of the $QQ\bar q\bar q$-type of tetraquarks with two heavy quarks and two light antiquarks. We present the first comprehensive estimate of the lifetime and leading decay modes of the exotic meson $bb\bar u\bar d$ with double beauty.
We have studied the masse spectra for the $cc\bar{b}\bar{b}$/$bb\bar{c}\bar{c}$ tetraquark states with quantum numbers $J^{P}=0^{\pm},1^{\pm}$, and $2^{+}$. We systematically construct the interpolating currents with various spin-parity quantum numbers and calculate their two-point correlation functions in the framework of QCD moment sum rule method. Our calculations show that the masses are about $12.3-12.4$ GeV for the positive parity $cc\bar{b}\bar{b}$ tetraquark ground states with $J^{P}=0^+, 1^+, 2^+$, while $12.8-13.1$ GeV for the negative parity channels with $J^{P}=0^-, 1^-$. The mass …
The goal of the present work is to obtain a reliable estimate of the masses of the ground and radially excited states of fully-heavy tetraquark systems. In order to do this, we use a nonrelativistic model of tetraquarks which are assumed to be compact and consist of diquark-antidiquark pairs. This nonrelativistic model is composed of Hulthen potential, a linear confining potential and spin-spin interaction. We computed ground, first, and second radially excited $cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$ tetraquark masses. It was found that predicted masses of ground states of $cc\bar{c}\bar{c}$…
We study the spectra of the doubly charmed tetraquark states in a diquark-antidiquark model. The doubly charmed tetraquark states form an antitriplet and a sextet configurations according to flavor SU(3) symmetry. For the tetraquark state $[qq'][\bar c\bar c]$, we show the mass for both bound and excited states. The two-body decays of tetraquark states $T^{cc}[0^+]$ and $T^{cc}[1^{--}]$ to charmed mesons have also been studied. In the end,the doubly charmed tetraquarks decays to a charmed baryon and a light baryon have been studied in the SU(3) flavor symmetry.
We have systematically calculated the mass spectra for S-wave and P-wave fully-charm $c\bar{c}c\bar{c}$ and fully-bottom $b\bar{b}b\bar{b}$ tetraquark states in the $\mathbf{8}_{[Q\bar{Q}]}\otimes \mathbf{8}_{[Q\bar{Q}]}$ color configuration, by using the moment QCD sum rule method. The masses for the fully-charm $c\bar cc\bar c$ tetraquark states are predicted about $6.3-6.5$ GeV for S-wave channels and $7.0-7.2$ GeV for P-wave channels. These results suggest the possibility that there are some $\mathbf{8}_{[c\bar{c}]}\otimes \mathbf{8}_{[c\bar{c}]}$ components in LHCb's di-$J/ψ$ structures. …
Flavor $SU(3)$ properties of beauty tetraquark states with three different light quarks
由$ \bar b s u \bar d$、$\bar b d s \bar u$和$\bar b u d \bar s$组成的美四夸克态$X(\bar b q'q'' \bar q )$是唯一的四价夸克态。虽然D0前两个状态的存在没有得到LHCb数据的证实，但这些状态的可能性仍然引起了很多兴趣，应该进一步研究。LHCb没有观测到$X(\bar b q'q'' \bar q )$态可能只是因为产生速率比LHCb的极限还要低，或者是在一些不同的质量范围内。本文以轻夸克$SU(3)$味对称性为准则，对美四夸克态的对称性进行了分类。包含三个不同轻夸克态的多重态必须是$SU(3)$表示的${\bf \bar 6}$或${\bf 15}$之一。通过构造首阶手征拉格朗日量，研究了这种四夸克态衰变为$B$介子和轻赝标八重态介子的可能性，并给出了确定这种四夸克态是属于${\bf \bar 6}$还是${\bf 15}$的搜索策略.如果$X(\bar b q'q''\bar q )$属于${\bf 15}$，则存在新的双电荷四夸克态$\bar b u u \bar d$和$\bar b u u \bar s$ .
Masses of the ground-state teraquarks composed from heavy $c$ and $b$ quarks and antiquarks are calculated in the diquark-antidiquark picture in the framework of the relativistic quark model based on the quasipotential approach. The quasipotentials of the quark-quark and diquark-antidiquark interactions are constructed similarly to the previous consideration of mesons and baryons. It is assumed that the diquark and antidiquark interact in the tetraquark as a whole and the internal structure of the diquarks is taken into account. All such tetraquarks are found above the thresholds of decays to …
For very heavy quarks $Q$, relations derived from heavy-quark symmetry predict the existence of novel narrow doubly heavy tetraquark states of the form $Q_iQ_j \bar q_k \bar q_l$ (subscripts label flavors), where $q$ designates a light quark. By evaluating finite-mass corrections, we predict that double-beauty states composed of $bb\bar u \bar d$, $bb\bar u \bar s$, and $bb\bar d \bar s$ will be stable against strong decays, whereas the double-charm states $cc \bar q_k \bar q_l$, mixed beauty+charm states $bc \bar q_k \bar q_l$, and heavier $bb \bar q_k \bar q_l$ states will dissociate into pa…
In this talk, we briefly report the investigations of the mass spectra for the $cc\bar c\bar c, bb\bar b\bar b$, $bc\bar b\bar c$ and $cc\bar b\bar b$ tetraquark states by using the QCD moment sum rule method. The calculations for the fully-charm $cc\bar c\bar c$ tetraquarks have been successfully predicted the existence of di-$J/ψ$ resonances including $X(6900)$ in LHCb's observation. The quantum numbers for these resonance structures are also suggested. More efforts are still needed in both theoretical and experimental aspects to study the properties of these fully-heavy tetraquark states. T…
The LHCb Collaboration has reported resonant activity in the channel $D^+ K^-$, identifying two components: $X_0(2900)$ with $J^P = 0^+$ at $2866 {\pm} 7$ MeV, $Γ_0=57{\pm} 13$ MeV and $X_1(2900)$ with $J^P = 1^-$ at $2904 {\pm} 7$ MeV, $Γ_1=110{\pm} 12$ MeV. We interpret the $X_0(2900)$ component as a $cs \bar u\bar d$ isosinglet compact tetraquark, calculating its mass to be $2863 {\pm} 12$ MeV. This is the first exotic hadron with open heavy flavor. The analogous $bs\bar u\bar d$ tetraquark is predicted at $6213 {\pm} 12$ MeV. We discuss possible interpretations of the heavier and wider $X_…
We apply the QCD sum rule method to systematically study the $S$- and $P$-wave fully-strange tetraquark states within the diquark-antidiquark picture. We systematically construct their interpolating currents by explicitly adding the covariant derivative operator. Our results suggest that the $f_0(2100)$, $X(2063)$, and $f_2(2010)$ may be explained as the $S$-wave $s s \bar s \bar s$ tetraquark states with the quantum numbers $J^{PC} = 0^{++}$, $1^{+-}$, and $2^{++}$, respectively. Our results also suggest that both the $X(2370)$ and $X(2500)$ may be explained as the $P$-wave $s s \bar s \bar s…
Motivated by the LHCb's new observation of structures in the $J/ψ$-pair invariant mass spectrum, for which could be classified as possible $cc\bar{c}\bar{c}$ tetraquark candidates, we systematically study $0^{+}$ fully-charmed tetraquark states through QCD sum rules. Making the development of calculation techniques to fourfold heavy hadronic systems, four different configuration currents with $0^{+}$ are considered and vacuum condensates up to dimension $6$ are included in the operator product expansion (OPE). Finally, mass values acquired for $0^{+}$ $cc\bar{c}\bar{c}$ tetraquark states agree…
We study the existence of fully-heavy hidden-flavor $bc\bar{b}\bar{c}$ tetraquark states with various $J^{PC}=0^{\pm+}, 0^{--},1^{\pm\pm}, 2^{++}$, by using the moment QCD sum rule method augmented by fundamental inequalities. Using the moment sum rule analyses, our calculation shows that the masses for the S-wave positive parity $bc\bar{b}\bar{c}$ tetraquark states are about $12.2-12.4$ GeV in both $[\mathbf{\bar{3}_c}]_{bc}\otimes[\mathbf{3_c}]_{\bar{b}\bar{c}}$ and $[\mathbf{6_c}]_{bc}\otimes[\mathbf{\bar{6}_c}]_{\bar{b}\bar{c}}$ color configuration channels. Except for two $0^{++}$ states,…
Inspired by recent measurement of possible fully charmed tetraquarks in LHCb Collaboration, we investigate the mass spectra of fully heavy tetraquarks $QQ \bar Q \bar Q$ in an extended relativized quark model. Our estimations indicate that the broad structure around 6.4 GeV should contain one or more ground $cc \bar c \bar c$ tetraquark states, while the narrow structure near 6.9 GeV can be categorized as the first radial excitation of $cc \bar c \bar c$ system. Moreover, with the wave functions of the tetraquarks and mesons, the strong decays of tetraquarks into heavy quarkonium pair are qual…
In this study, we investigate the discovery potential of double-charm tetraquarks $T^{\{cc\}}_{[\bar{q}\bar{q}']}$. We find that their production cross sections at the LHCb with $\sqrt{s} = 13$ TeV reach $\mathcal{O}(10^4)$ pb, which indicates that the LHCb has collected $\mathcal{O}(10^8)$ such particles. Through the decay channels of $T^{\{cc\}}_{[\bar{u}\bar{d}]}\to D^{+}K^{-}π^{+}$ or $D^0D^+γ$ (if stable) or $T^{\{cc\}}_{[\bar{u}\bar{d}]}\to D^0D^{*+}\to D^0D^0π^+$ (if unstable), it is highly expected that they get discovered at the LHCb in the near future. We also discuss the productions…
We study the decay behaviors of the fully-bottom tetraquark states within the diquark-antidiquark picture, and calculate their relative branching ratios through the Fierz rearrangement. Our results suggest that the $C=+$ states can be searched for in the $μ^+ μ^- Υ(1S)$ and $μ^+ μ^- Υ(2S)$ channels with the relative branching ratio $\mathcal{B}(X \to μμΥ(2S)) / \mathcal{B}(X \to μμΥ(1S)) \approx 0.4$. Our results also suggest that the $C=-$ states can be searched for in the $μ^+ μ^- η_b(1S)$ and $μ^+ μ^- η_b(2S)$ channels with the similar relative branching ratio $\mathcal{B}(X \to μμη_b(2S)) …
We have studied the masses for fully open-flavor tetraquark states $bc\bar{q}\bar{s}$ and $sc\bar{q}\bar{b}$ with quantum numbers $J^{P}=0^{+},1^{+}$. We systematically construct all diquark-antiquark interpolating currents and calculate the two-point correlation functions and spectral densities in the framework of QCD sum rule method. Our calculations show that the masses are about $7.1-7.2$ GeV for the $bc\bar{q}\bar{s}$ tetraquark states and $7.0-7.1$ GeV for the $sc\bar{q}\bar{b}$ tetraquarks. The masses of $bc\bar{q}\bar{s}$ tetraquarks are below the thresholds of $\bar{B}_{s}D$ and $\bar…
We have calculated the mass spectra for the $\bar{D}_s^{(*)}D^{(*)}$ molecular states and $sc\bar q\bar c$ tetraquark states with $J^P=0^+, 1^+, 2^+$. The masses of the axial-vector $\bar{D}_sD^{*}$, $\bar{D}_s^{*}D$ molecular states and $\mathbf{1}_{[sc]} \oplus \mathbf{0}_{[\bar q \bar{c}]}$, $\mathbf{0}_{[sc]} \oplus \mathbf{1}_{[\bar q \bar{c}]}$ tetraquark states are predicted to be around 3.98 GeV, which are in good agreement with the mass of $Z_{cs}(3985)^-$ from BESIII \cite{besiii2020Zcs}. In both the molecular and diquark-antidiquark pictures, our results suggest that there may exist…
Within the framework of QCD sum rules, we have investigated the tetraquark states with three heavy quarks. We systematically construct the interpolating currents for the possible $cc\bar{c}\bar{q}$, $cc\bar{b}\bar{q}$, $bc\bar{b}\bar{q}$, $bb\bar{b}\bar{q}$ tetraquark states with quantum numbers $J^{P}=0^{+}$ and $J^{P}=1^{+}$. Using these interpolating currents, we have calculated the two-point correlation functions and extracted the mass spectra for the above tetraquark states. We also discuss the decay patterns of these tetraquarks, and notice that the $cc\bar{c}\bar{q}$, $cc\bar{b}\bar{q}$…
We calculate the spectrum of $q\bar q c \bar c$ and $s\bar s c \bar c$ tetraquarks, where $q$, $s$ and $c$ stand for light ($u,d$), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a $q\bar q c \bar c$ ($s\bar s c \bar c$) tetraquark configuration is made up of a heavy-light diquark, $q c$ ($sc$), and anti-diquark, $\bar q \bar c$ ($\bar s \bar c$). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm ($…
We investigate the mass spectrum of the $ss \bar s \bar s$ tetraquark states within the relativized quark model. By solving the Schrödinger-like equation with the relativized potential, the masses of the $S-$ and $P-$wave $ss \bar s \bar s$ tetraquarks are obtained. The screening effects are also taken into account. It is found that the observed resonant structure $X(2239)$ in the $e^+e^- \to K^+K^-$ process by BESIII Collaboration can be assigned as a $P-$wave $1^{--}$ $ss \bar s \bar s$ tetraquark state. Furthermore, the radiative transition and strong decay behaviors of this structure are a…
Evidence for the existence of $u d \bar{b} \bar{b}$ and the non-existence of $s s \bar{b} \bar{b}$ and $c c \bar{b} \bar{b}$ tetraquarks from lattice QCD
We study lifetimes and weak decays of the triply heavy tetraquarks ${b\bar c}{b\bar q}$. Following the heavy quark expanding(HQE), the lifetimes of tetraquarks ${b\bar c}{b\bar q}$ can be expressed as the summation of different dimension operators. Particularly, we obtain the lifetimes of ${b\bar c}{b\bar q}$ at the next-to-leading order(NLO) given as $τ(T^{\{bb\}}_{\{\bar c\bar q\}})=0.70\times 10^{-12}s$. Besides, we construct the weak decays Hamiltonian of ${b\bar c}{b\bar q}$ in hadronic level under the SU(3) flavor symmetry. The discussion of the Hamiltonian can deduce the decay amplitude…
We perform a quantitative analysis of the decays of $cc\bar c\bar c$ tetraquarks with $J^{PC}=0^{++}, 2^{++}$ into 4 muons and into hidden- and open-charm mesons and estimate, for the first time, the fully charmed tetraquark decay width. The calculated cross section upper limit is $\sim 40$ fb for the 4 muons channel, and $\sim 28$ nb for the $D^{(*)} \bar D^{(*)} \to eμ$ channel. On the basis of our results, with the present sensitivity LHCb should detect both signals, for $0^{++}$ and $2^{++}$ fully-charmed tetraquarks.
Using an extended chromomagnetic model, we perform a systematic study of the masses of the doubly heavy tetraquarks. We find that the ground states of the doubly heavy tetraquarks are dominated by color-triplet $\ket{(qq)^{\bar{3}_{c}}(\bar{Q}\bar{Q})^{3_{c}}}$ configuration, which is opposite to that of the fully heavy tetraquarks. The combined results suggest that the color-triplet configuration becomes more important when the mass difference between the quarks and antiquarks increases. We find three stable states which lie below the thresholds of two pseudoscalar mesons. They are the $IJ^{P…
We apply the method of QCD sum rules to study the $s s \bar s \bar s$ tetraquark states of $J^{PC} = 0^{-+}$. We construct all the relevant $s s \bar s \bar s$ tetraquark currents, and find that there are only two independent ones. We use them to further construct two weakly-correlated mixed currents. One of them leads to reliable QCD sum rule results and the mass is extracted to be $2.51^{+0.15}_{-0.12}$ GeV, suggesting that the $X(2370)$ or the $X(2500)$ can be explained as the $ss\bar s\bar s$ tetraquark state of $J^{PC} = 0^{-+}$. To verify this interpretation, we propose to further study …
We study the mass spectra of D-wave excited $cs\bar{c}\bar{s}$ tetraquark states with $J^{PC}=1^{++}$ and $1^{+-}$ in both symmetric $\mathbf{6}_{cs}\otimes\bar{\mathbf{6}}_{\bar{c}\bar{s}}$ and antisymmetric $\bar{\mathbf{3}}_{cs}\otimes\mathbf{3}_{\bar{c}\bar{s}}$ color configurations by using the QCD sum rule method. We construct the D-wave diquark-antidiquark type of $cs\bar{c}\bar{s}$ tetraquark interpolating currents in various excitation structures with $(L_λ,L_ρ\{l_{ρ_1},l_{ρ_2}\})=(2,0\{0,0\}),(1,1\{1,0\}),(1,1\{0,1\}),(0,2\{1,1\}),(0,2\{2,0\}),(0,2\{0,2\})$. Our results support to in…
We use the Laplace/Borel sum rules (LSR) and the finite energy/local duality sum rules (FESR) to investigate the non-strange $ud\bar u\bar d$ and hidden-strange $us\bar u\bar s$ tetraquark states with exotic quantum numbers $J^{PC}=0^{+-}$ . We systematically construct all eight possible tetraquark currents in this channel without covariant derivative operator. Our analyses show that the $ud\bar u\bar d$ systems have good behaviour of sum rule stability and expansion series convergence in both the LSR and FESR analyses, while the LSR for the $us\bar u\bar s$ states do not associate with conver…
In this article, we construct the axialvector-diquark-axialvector-antidiquark type currents to study both the vector and axialvector $QQ\bar{Q}\bar{Q}$ tetraquark states with the QCD sum rules, and obtain the masses $M_{Y(cc\bar{c}\bar{c},1^{+-})} =6.05\pm0.08\,\rm{GeV}$, $M_{Y(cc\bar{c}\bar{c},1^{--})} =6.11\pm0.08\,\rm{GeV}$, $M_{Y(bb\bar{b}\bar{b},1^{+-})} =18.84\pm0.09\,\rm{GeV}$, $M_{Y(bb\bar{b}\bar{b},1^{--})} =18.89\pm0.09\,\rm{GeV}$. The vector tetraquark states lie $40\,\rm{MeV}$ above the corresponding centroids of the $0^{++}$, $1^{+-}$ and $2^{++}$ tetraquark states, which is a typ…
In the diquark-diantiquark composition, we study the masses of hidden charm tetraquark systems ($cq\bar{c}\bar{q}$, $cs\bar{c}\bar{s}$ and $cs\bar{c}\bar{q}$) using a linear confinement potential. In this study, we have factorized the four body system into three subsequent two body systems. To remove degeneracy in the S and P wave masses of mesons and tetraquark states, the spin-spin, spin orbit and tensor components of the confined one gluon exchange interactions are employed. In this attempt, we have been able to assign the $ψ(4230)$ as pure $cq\bar{c}\bar{q}$ tetraquark state. $ψ(4360)$ and…
In present work, we systematically calculate the mass spectra of open charm and bottom tetraquarks $q q\bar q \bar Q$ within an extended relativized quark model. The four-body relativized Hamiltonians including the Coulomb potential, confining potential, spin-spin interactions, and relativistic corrections are solved by using the variational method. It is found that the predicted masses of four $0^+$ $ud\bar s \bar c$ states are 2765, 3065, 3152, and 3396 MeV, which disfavor the assignment of the newly observed $X_0(2900)$ as a compact tetraquark. Moreover, the whole mass spectra of the open c…
The weak decays of the axial-vector tetraquark $T_{bb;\bar{u} \bar{d}}^{-}$ to the scalar state $Z_{bc;\bar{u} \bar{d}}^{0}$ are investigated using the QCD three-point sum rule approach. In order to explore the process $T_{bb; \bar{u} \bar{d}}^{-} \to Z_{bc;\bar{u} \bar{d}}^{0}l \bar{ν_l}$, we recalculate the spectroscopic parameters of the tetraquark $T_{bb;\bar{u} \bar{d}}^{-}$ and find the mass and coupling of the scalar four-quark system $Z_{bc;\bar{u} \bar{d}}^{0}$, which are important ingredients of calculations. The spectroscopic parameters of these tetraquarks are computed in the frame…
In the present work, we construct the color-singlet-color-singlet type four-quark currents to investigate the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ tetraquark molecular states with the $J^{PC}=1^{--}$ and $1^{-+}$ via the QCD sum rules, and obtain satisfactory results. We can search for the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ tetraquark molecular states with the $J^{PC}=1^{--}$ and $1^{-+}$ at the BESIII and Belle II in the future.
We perform a quantitative analysis of the $bb\bar{b}\bar{b}$ tetraquark decays into hidden- and open-bottom mesons and calculate, for the first time, the $bb\bar{b}\bar{b}$ tetraquark total decay width. On the basis of our results, we propose the $bb\bar{b}\bar{b} \to B^{+} B^{-} (B^0 \bar{B}^0) (B_s^0 \bar{B}_s^0) \to l^{+} l^{-}+\text{X}$ decays as the most suitable channels to observe the $bb\bar{b}\bar{b}$ tetraquark states, since the calculated two-lepton cross section upper limit, $\simeq 39 $ fb, is so large as to be potentially detectable with the 2018 LHCb sensitivity, paving the way …
We apply the method of QCD sum rules to study the structure $X$ newly observed by the BESIII Collaboration in the $ϕη^\prime$ mass spectrum in 2.0-2.1 GeV region in the $J/ψ\rightarrow ϕηη^\prime$ decay. We construct all the $s s \bar s \bar s$ tetraquark currents with $J^{PC} = 1^{+-}$, and use them to perform QCD sum rule analyses. One current leads to reliable QCD sum rule results and the mass is extracted to be $2.00^{+0.10}_{-0.09}$ GeV, suggesting that the structure $X$ can be interpreted as an $s s \bar s \bar s$ tetraquark state with $J^{PC} = 1^{+-}$. The $Y(2175)$ can be interpreted …
In this article, we study the ground-state mass of full-heavy tetraquarks $cc\bar c\bar c$ and $bb\bar b \bar b$ with solving the nonrelativistic four-body systems. The flux-tube configurations, the tetraquark four-body potential butterfly, and the dimeson potential flip-flop of SU(3) lattice quantum chromodynamics have been applied to describe the tetraquark interaction. Our numerical analysis indicates that the disconnected and connected static potentials can predict the mass of tetraquark very close to experimental data.
In the framework of the quark delocalization color screening model, we investigate tetraquarks composed of $us\bar{d}\bar{b}$ and $ud\bar{s}\bar{b}$ in two structures: meson-meson structure and diquark-antidiquark structure. Neither bound state nor resonance state is found in the system composed of $us\bar{d}\bar{b}$. The reported $X(5568)$ cannot be explained as a molecular state or a diquark-antidiquark resonance of $us\bar{d}\bar{b}$ in present calculation. However, two bound states of the diquark-antidiquark structure are obtained in the tetraquarks system composed of $ud\bar{s}\bar{b}$: a…
The mass and coupling of the doubly charmed $J^P=0^{-}$ diquark-antidiquark states $T_{cc;\bar{s} \bar{s}}^{++}$ and $T_{cc;\bar{d} \bar{s}}^{++}$ that bear two units of the electric charge are calculated by means of QCD two-point sum rule method. Computations are carried out by taking into account vacuum condensates up to and including terms of tenth dimension. The dominant $S$-wave decays of these tetraquarks to a pair of conventional $ D_{s}^{+}D_{s0}^{\ast +}(2317)$ and $D^{+}D_{s0}^{\ast +}(2317)$ mesons are explored using QCD three-point sum rule approach, and their widths are found. The…
