Related papers: Are there compact heavy four-quark bound states?
In this paper, we adopt an extended relativized quark model to investigate the triply-heavy tetrquarks systematically. The mass spectra are obtained by solving the four-body relativized Hamiltonian including the Coulomb potential, confining…
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…
We suggest a physical definition of the confinement mass scale in QCD in the framework of non-perturbative, gauge invariant QCD, where all possible gluons exchanged between any pair of quark lines are included; and we insist that a stable,…
We discuss the stability of multiquark systems within the recent model of Glozman et al. where the chromomagnetic hyperfine interaction is replaced by pseudoscalar-meson exchange contributions. In this model the (u,d) diquark S=0 I=0 is…
A potential quark model is used to search for a $P_{c\bar{c}s}^0=(c\bar{c}uds)^0$, $J^P=1/2^-$ pentaquark state that has recently been observed experimentally by the LHCb collaboration at 4338.2 MeV, with a width of 7.0 MeV and high…
Four-quark states are discussed within the constituent quark model. Incompleteness of existed studies of four-quark state with QCD sum rule is analyzed. The masses of diquark cluster were determined by QCD sum rules, and light four-quark…
Developing the calculation techniques to fivefold heavy hadrons, we perform the study of novel fully-heavy $QQQQ\bar{Q}$ pentaquark states by the QCD sum rule approach that is firmly based on the QCD basic theory. Numerically, masses of…
This is the second of two companion papers in which we continue to develop the construction of the doubly heavy pentaquark systems using the gauge/string duality. In this paper, we propose a stringy description of the $Q\bar Qqqq$ system in…
In the framework of the chiral quark model, we investigate the $Qq\bar{q}\bar{q}$ ($Q= c, b$ and $q= u, d$) tetraquark system with two structures: $Q\bar{q}$-$q\bar{q}$ and $Qq$-$\bar{q}\bar{q}$. The bound-state calculation shows that for…
We summarize previous work on $\bar b \bar bud$ four-quark systems in the Born-Oppenheimer approximation and discuss first steps towards an extension to the theoretically more challenging $b\bar b u\bar d$ system. Strategies to identify a…
Recently the LHCb Collaboration announced the first observation of nontrivial structures in the double-$J/\psi$ mass spectrum in the mass range 6.2-7.2 GeV, and a theoretical coupled-channel analysis of these data performed in Phys. Rev.…
A non-covariant but approximately relativistic two-body wave equation (Breit equation) describing the quantum mechanics of two fermions interacting with one another through a potential containing scalar, pseudoscalar and vector parts is…
We present the results of a lattice calculation of four-quark states with the quark contents $\bar{b}\bar{c}q_1q_2$ where $q_1,q_2 \in u,d,s$. For the spin 1 states, when the light quark ($q_1, q_2$) masses are lighter, we find at least one…
We discuss a general theoretical framework for the study of bound states made of two heavy quarks. For states below threshold, the framework has been developed to the level of providing precision studies for several charmonium and…
Inspired by the recent observation of a very narrow state, called $T_{cc}^+$, by the LHCb collaboration, the possible bound states and low-lying resonance states of the doubly heavy tetraquark states $cc\bar{u}\bar{d}$ ($T_{cc}$) and…
In the framework of an extended chromomagnetic model, we systematically study the mass spectrum of the $S$-wave $qQ\bar{Q}\bar{Q}$ tetraquarks. Their mass spectra are mainly determined by the color interaction. For the $qc\bar{c}\bar{c}$,…
Energy spectrum of doubly heavy tetraquarks, $T_{QQ}$ ($QQ \bar{q} \bar{q}$ with $Q = c, b$ and $q = u, d, s$), is studied in the potential chiral-diquark model. Using the chiral effective theory of diquarks and the quark-diquark-based…
We review weakly-bound heavy quarkonium systems using effective field theories of QCD. We concentrate on potential Non-Relativistic QCD, which provides with a well founded connection between QCD and descriptions of the heavy quarkonium…
Tetraquark properties are examined in the limit of large $N_c$ of color in QCD. The qualitative differences between molecular and compact tetraquarks are outlined. Consequences of the possible existence of compact tetraquarks are analyzed…
The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of meson spectroscopy, beyond the simple quark--antiquark…