Related papers: X & Y
The models for the internal structure of the newly found four-quark charmonium-like resonance $Z_c(3900)$ are discussed: the molecular model as well as the hadro-charmonium and tetraquark schemes. It is argued that it would be possible to…
Recent results on the study of the electromagnetic structure of nucleon resonances, the spin structure of proton and neutrons at small and intermediate photon virtualities, and the search for exotic pentaquark baryons are presented.
This paper comments on the recently reported quantum oscillations in underdoped YBCO crystals. The implications to other experiments and some hurdles to validating the proposed interpretation are discussed.
The XYZ mesons are unexpected mesons containing a heavy quark-antiquark pair that have been discovered during the last decade. The models for the XYZ mesons that have been proposed include conventional quarkonium, quarkonium hybrids, and…
In this Letter we interpret the Y(4260), a state recently discovered by the BaBar Collaboration that has a mass within the range of conventional charmonium states, as having a molecular-state structure. In our scheme this molecular-like…
Recent results on the search for pentaquarks and on charmonium spectroscopy at BaBar are reviewed. The latter includes the observation of the puzzling new state X(3872) -> J/psi pi+ pi- in B decays, and the searches for X(3872) in two-body…
We study the vector-vector interaction within the framework of the hidden gauge formalism for the channels with quantum numbers Charm C=0 and Strangeness S=0 in the energy region around 4000 MeV. By looking for poles in the complex plane we…
In this talk, after a short overview of the history of the discovery of tetra-quarks and penta-quarks, we will discuss a possible interpretation of such states in the framework of a 40-years-old "string junction" picture that allows a…
Contrary to almost standard opinion that the X(3872) resonance is the D^{*0}\bar D^0+c.c. molecule or the qc\bar q\bar c four-quark state, we discuss the scenario where the X(3872)resonance is the c\bar c = \chi_{c1}(2P) charmonium which…
Since the discovery of X(3872), its structure has been in ceaseless dispute. The data of $X(3872)\rightarrow \pi^+\pi^-\pi^0 J/\psi$ suggest that X(3872) may be a high-spin charmonium-like of $2^{-+}$. In terms of the light front quark…
The new narrow resonance which has been observed at the B factories is assigned to the I_z=0 component of iso-triplet charmed four-quark mesons, and as its consequence, existence of additional narrow resonances in different channels is…
We report on some ideas concerning the nature of the X(3872) resonance and the need for approximately equal charged and neutral components of $D \bar{D}^* +cc$. Then we discuss how some hidden charm states are obtained from the interaction…
It is explained why the interpretation of the resonances $f_{2}(1270),$ $a_{1}(1260)$ and $f_{0}(1370)$ as quark-antiquark states is legitimate. The result of the quark model and of recently performed Bethe-Salpeter studies are not…
We present a short review on the recent progresses that have been made in meson spectroscopy. We discuss the experimental discoveries made at the BaBar and Belle experiments, as well as the possible interpretations of the new resonances.
The positive parity $\chi_{cJ}(2P)$ charmonium states are expected to lie around the 3.9 GeV/$c^2$ energy region, according to the predictions of quark models. However, a plethora of states with difficult assignment and unconventional…
BES III Collaboration has recently observed a vector resonance in the chi_{c0} omega channel, at a mass of about 4220 MeV, named Y(4220). Hints of a similar structure appear in the h_c pi+ pi- channel. We find that the two observations are…
The X(3872) and Y(3940) properties and decay modes from Belle are reviewed and the results on a search for the decay $B^+\ra h_c K^+$, $h_c\ra \eta_c \gamma$ at Belle are presented.
It is suggested that the resonance $\psi(3770)$ may contain a sizeable ($O(10%)$ in terms of the probability weight factor) four-quark component with the up- and down- quarks and antiquarks in addition to the $c {\bar c}$ pair, which…
Following the recent confirmation of the Z+(4430) resonance with J^{PG}=1^{++}, we have re-examined the model of S- and P-wave tetraquarks. We propose a `type-II' diquark-antidiquark model which shows to be very effective at producing a…
In this work, we consider the canonical charmonium assignments for Y(4360) and Y(4660). Y(4660) is good candidate of $\rm 5 ^3S_1$ $c\bar{c}$ state, the possibility of Y(4360) as a $\rm 3 ^3D_1$ $c\bar{c}$ state is studied, and the…