Related papers: Molecular structures in charmonium spectrum: The $…
The role of $q\bar q$ components in the nucleon and the N(1440) resonance is studied by explicit coupling of the lowest positive parity $qqqq\bar q$ state to the $qqq$ components in the harmonic oscillator quark model. The lowest energy…
We incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of higher charmonium. We calculate the masses,…
Inspired by the recent observation of exotic resonances $X(4140)$, $X(4274)$, $X(4350)$, $X(4500)$ and $X(4700)$ reported by several experiment collaborations, we investigated the four-quark system $cs\bar c\bar s$ with quantum numbers…
The nature of resonances and excited states near decay thresholds is encoded in scattering amplitudes, which can be extracted from single-particle and multiparticle correlators in finite volumes. Lattice calculations have only recently…
We present a systematic and selfconsistent analysis of four-quark charmonium states and applied it to study compact four-quark systems and meson-meson molecules. Our results are robust and should serve to clarify the situation of charmonium…
The year 2024 marked the 50th anniversary of the discovery of the $J/\psi$ particle, which unveiled the charm quark and the charmonium spectrum, instigating the "November Revolution" in particle physics. This discovery catalyzed the…
Observations of new charmonium(-like) and bottomonium(-like) states (sometimes refered to as "XYZ" states) at e+e- colliders have changed our picture of quarkonia systems as QCD bound states. Potential models with a linear confinement…
The pole counting rule is a powerful and model-independent method to distinguish a confining state from a hadronic molecule. It has been applied to the explorations of $X(6900)$, $X_1(2900)$ as well as $Z_c(3900)$, $X(3872)$, $X(4660)$,…
Coulomb charges confined by a harmonic potential display a rich structure at strong coupling, both classical and quantum. A simple density functional theory is reviewed showing the essential role of correlations in forming shell structure…
In this article, we assume that there exists a pseudoscalar $D_s{\bar D}_{s0}(2317)$ molecular state and study its mass with the molecule-type interpolating current in details using the QCD sum rules. The numerical result disfavors…
We investigated the bound state problem of the S wave charged $D_1 \bar{D}^*$ ($D_1' \bar{D}^*$) system in a chiral quark model by solving the resonating group method equation. Our preliminary study does not favor the molecular assumption…
Since 2003 many charmonium-like states were observed experimentally. Especially those charged charmonium-like $Z_c$ states and bottomonium-like $Z_b$ states cannot be accommodated within the naive quark model, which are good candidates of…
Heavy-light diquarks can be the building blocks of a rich spectrum of states which can accommodate some of the newly observed charmonium-like resonances not fitting a pure c-cbar assignment. We examine this possibility for hidden and open…
The $q\bar q$ spectrum is studied in a generalized constituent quark model constrained in the study of the $NN$ phenomenology and the baryon spectrum. An overall good fit to the available experimental data is obtained. A detailed analysis…
We investigate whether the newly observed narrow resonance $Z_{c}(4025)$ can be described as a $D^{*}\bar{D^{*}}$ molecular state with quantum numbers $J^{P}=1^{+}$. Using QCD sum rules, we consider contributions up to dimension six in the…
By using a combined amplitude analysis of the $\gamma\gamma\rightarrow D\bar{D}$ and $\gamma\gamma\rightarrow J/\psi\omega$ data, we demonstrate that the $X(3915)$, which is quoted as a $J^{PC}=0^{++}$ state in the Particle Data Group…
The discovery of a new charged structure in the $K^+$ recoil-mass spectrum near the $D^-_s D^{*0}/D^{*-}_sD^0$ threshold, dubbed $Z_{cs}(3985)^-$, reinforce the idea that the structure of hadrons goes beyond the naive $qqq$ and the $q\bar…
The question of classicality is addressed in relation with the shape of the nuclear skeleton of molecular systems. As the most natural environment, the electrons of the molecule are considered as continuously monitoring agents for the…
Very recently the BaBar collaboration has put forward a claim that the X(3872) is not a 1^++ resonance, as most of the phenomenological work on the subject was relying on, but rather a 2^-+ one. We examine the consequences of this quantum…
BaBar and Belle have recently revived the interest in charmonium spectroscopy, discovering many unexpected resonances. In this review, I'll focus mostly on the states found in B decays and double $\ccbar$. A better understanding of their…