Related papers: Theoretical Development on Pentaquarks
We calculate the widths of the various pentaquarks in a relativistic model in which the pentaquark is considered to be composed of a scalar diquark and a spin 1/2 triquark. We consider both positive and negative parity for the pentaquark.…
Indirect searches, and in particular rare decays, have proven to be a fruitful field to search for New Physics beyond the Standard Model. While the down-quark sector (B and K) have been studied in detail, less attention was devoted to charm…
Based on the fact that the long expected pentaquark which possesses the exotic quantum numbers of $B=1$ and $S=1$ was not experimentally found, although exotic states of $XYZ$ have been observed recently, we conjecture that the heavy…
We discuss the specific features of extracting properties of the exotic polyquark hadrons (tetraquarks, pentaquarks) compared to the usual hadrons by the QCD sum-rule approach. In the case of the ordinary hadrons, already the one-loop…
We analyse the decay $\Theta_s(1/2^+)\to NK$ in a non-relativistic Fock space description using three and five constituent quarks for the nucleon and the pentaquark, respectively. Following Jaffe and Wilczek \cite{jw}, we assume that…
A large data set of proton-nucleus collisions at sqrt(s) =41.6 GeV has been searched for Theta+ and Xi(1862) pentaquark candidates. In 2x10**8 inelastic events we find no evidence for narrow signals (sigma=5 MeV/c**2) in the Theta+ --> pK0s…
The last decade has seen a marked shift in how the internal structure of hadrons is understood. Modern experimental facilities, new theoretical techniques for the continuum bound-state problem and progress with lattice-regularised QCD have…
A review is given to pentaquark mass predictions in quark models and QCD. It is pointed out that no successful quark model prediction is available for low-lying pentaquark states. Some new results of direct application of QCD, QCD sum rules…
This HADRON05 summary covers the topics of (1) mesons containing heavy quarks, and (2) theory. The new material discussed here is taken mainly from plenary presentations. We specifically emphasize new or recent results in spectroscopy that…
The present experimental evidence for the existence of light pentaquarks is reviewed, including both positive and null results. I also discuss the CLAS experiments at Jefferson Laboratory that are forthcoming in the near future to address…
Evidence for a narrow baryon state at 1528 +- 2.6(stat) +- 2.1(syst) MeV is presented in quasi-real photoproduction on a deuterium target through the decay channel p,K0 to p,pi+,pi-. The statistical significance of the peak in the p,K0…
The past seventeen years have witnessed tremendous progress on the experimental and theoretical explorations of the multiquark states. The hidden-charm and hidden-bottom multiquark systems were reviewed extensively in [Phys. Rept. 639…
In this paper the masses and decay processes of several new strange, charmed and bottomed exotic pentaquarks are predicted. Multiquarks are studied microscopically in a standard quark model. In pure ground-state pentaquarks the short-range…
Current evidence does not favor the existence of the \thplus pentaquark, which was reported by several groups in the years after 2002. The question naturally arises: how could many groups could have seen fluctuations in their data at the…
We present a very general argument that the analogue of a heavy pentaquark (a state with the quantum numbers of a baryon combined with an additional light quark and a heavy antiquark) must exist as a particle stable under strong…
In this talk, multiquarks are studied microscopically in a standard quark model. In pure ground-state pentaquarks the short-range interaction is computed and it is shown to be repulsive. An additional quark-antiquark pair is then…
The recently observed pentaquark baryons $\Theta^{+}$ and $\Xi^{--}$ are studied in the dual gravity theory of QCD. By developing a general formulation useful for studying the branched string web in a curved space, simple mass formulae of…
To understand the whole set of positive and null data on the Theta+(1530)-production, we suggest the hypothesis that multiquark hadrons are mainly generated from many-quark states, which emerge either as short-term hadron fluctuations, or…
Starting from 2003, the discovery of a large amount of the so-called exotic hadronic states, i.e., the $XYZ$ states, the pentaquark states as well as the tetraquark states, have not only revived studies of hadron spectroscopy, but also…
The earlier search at HERMES for narrow baryon states excited in quasi-real photoproduction, decaying through the channel $pK_S^0\rightarrow p\pi^+\pi^-$, has been extended with improved decay-particle reconstruction, more advanced particle…