Related papers: Have Pentaquark States Been seen?
A new mechanism of the production of hypothetical $\Theta(ud\bar{s}ud)^+$ pentaquark state is suggested. The considered mechanism is based on the exchange by exotic Regge trajectories in the $t$ channel. It is shown that the momentum…
We report the results of a search for the Theta*++ pentaquark in the decay B+ -> Theta*++ pbar where Theta*++ -> pK+ using 81fb^-1 of data collected on the Upsilon(4S) resonance with the BaBar detector at PEP-II. We find an upper limit on…
A number of candidate multiquark hadrons, i.e., particle resonances with substructures that are more complex than the quark-antiquark mesons and three-quark baryons that are prescribed in the textbooks, have recently been observed. In this…
A number of new four-quark states containing from one to four charm or anti-charm quarks have been observed recently. Many of these new states have been discovered at the LHC. The production of these states via intrinsic charm in the proton…
The LHCb Collaboration at the Large Hadron Collider at CERN discovered two pentaquark states $P_c(4380)$ and $P_c(4450)$. These two hidden-charm states are interpreted as the loosely bound $\Sigma_c(2455)D^*$ and $\Sigma_c^*(2520)D^*$…
Motivated by the recent discovery of the exotic S=+1 narrow baryon resonance Theta^+ at 1540 MeV, with quark content {uudd sbar}, we conjecture the existence of its anti-charmed analogue Theta_c, with quark content {uudd cbar}, and compute…
Additional broader I=0 states in the KN channel near $\Theta^+$(1540) are expected in many models, making the absence of any signature in the K$^+$-deuteron scattering data even more puzzling. In an ideal "three-body" picture the $\Theta$…
Claims concerning the possible discovery of the \Theta^+ pentaquark, with minimal quark content uudd\bar{s}, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various pentaquark…
Recent experiments at the LHCb detector have once again raised the possibility that quark bags may exist containing more than three quarks. Specifically the LHCb collaboration points to evidence for hadronic resonances decaying into…
The penta-quark(5Q) Theta^+(1540) is studied in anisotropic lattice QCD with renormalized anisotropy a_s/a_t=4 for a high-precision measurement. Both the positive and the negative parity 5Q baryons are studied using a non-NK type…
In the framework of the color-magnetic interaction, we have systematically studied the mass splittings of the possible hidden-charm pentaquarks $qqqc\bar{c}$ ($q=u,d,s$) where the three light quarks are in a color-octet state. We find that…
There are experimental evidences for the existence of narrow states $\Theta^+$ and $\Theta_c$ with the same quantum numbers of $uudd\bar s$ and $uudd\bar c$ pentaquarks and also $NK^{(*)}$ and $ND^{(*)}$ molecular states. Their masses…
The existence of a shallow or virtual tetraquark state, $cc\bar{u}\bar{d}$, is discussed. Using the putative masses for the doubly charmed baryons ($ccu/ccd$) from SELEX, the mass of the $cc\bar{u}\bar{d}$ state is estimated to be about…
I report on recent studies of hadronic physics performed by the BaBar Collaboration. Emphasis is given to the measurement of the properties of newly discovered charmed hadrons and to the searches for light and heavy pentaquarks.
This paper focuses on tetraquarks containing one heavy quark and one heavy antiquark in the formal limit where the heavy quark masses go to infinity. It extends the theoretical framework developed for tetraquark containing two heavy quarks…
We provide a simple explanation for the observed hidden-charm pentaquarks as bound states in Born-Oppenheimer potentials. We identify $P_{c\bar{c}}(4312)^+$, $P_{c\bar{c}}(4440)^+$, and $P_{c\bar{c}}(4457)^+$ as heavy-quark spin states in a…
Using the bound state version of the topological soliton model for the baryons we show that the existence of a bound (or quasi-bound) $\bar D$-soliton state leads to the possibility of having hidden charm pentaquarks with quantum numbers…
A general study of pentaquarks built with four quarks in a L=1 state and an antiquark in S-wave shows that several of such states are forbidden by a selection rule, which holds in the limit of flavour symmetry, to decay into a baryon and a…
In this work we investigate the existence of bound states for doubly heavy tetraquark systems $ \bar{Q}\bar{Q}'qq' $ in a full lattice-QCD computation, where heavy bottom quarks are treated in the framework of non-relativistic QCD. We focus…
Recent evidence for pentaquark baryons in the channels $\Xi^-\pi^-$, $\Xi^-\pi^+$ and their anti-particles claimed by the NA49 collaboration is critically confronted with the vast amount of existing data on $\Xi$ spectroscopy which was…