Related papers: A Selection Rule for Multiquark Decays
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…
The pentaquark state of $\Theta^{+}(uudd\bar{s})$ has been observed to decay with two decay modes: $\Theta^+\to n K^+$ and $\Theta^+ \to p K^0$. The decay probability ratio of the two decay modes is studied with general symmetry…
It is pointed out that the previously suggested interpretation of the hidden-charm pentaquarks $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ as molecular bound states of $\Sigma_c \bar D$ and $\Sigma_c \bar D^*$ baryon-meson pairs gives rise to…
We investigate the decay modes of pentaquark baryons for both the antidecuplet and the octet states, which were recently claimed by Close and Dudek to be potentially narrow due to a hidden selection rule. We discuss how ideal mixing between…
Assuming that the recently observed $\Theta^+$ and $\Xi^{--}$ are members of an anti-decuplet of SU(3), decays to ground state baryons and mesons are calculated using an effective Lagrangian which incorporates chiral and SU(3) symmetry. We…
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $\Theta \to K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{\Theta nK}$ which is…
Based on the flavor SU(3) symmetry, we classify all the possible pentaquark baryons made of four quarks and one antiquark. In particular, we present possible multiplets of pentaquarks, their interactions with mesons, and the mass relations…
We present results for the selfenergy of the $\Theta^+$ pentaquark in nuclei associated with two sources: the $KN$ decay of the $\Theta^+$ and the two meson baryon decay channels of the $\Theta^+$ partners in an antidecuplet of baryons. The…
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…
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $\Theta \rightarrow K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{\Theta nK}$…
Recently several experiments have reported evidences for pentaquark $\Theta^+$. H1 experiment at HERA-B has also reported evidence for $\Theta_c$. $\Theta^+$ is interpreted as a bound state of an $\bar s$ with other four light quarks $udud$…
By studying the spin structure of an S-wave meson-antimeson system in the heavy quark limit, we find two selection rules for the $c\bar{c}$ spin $J_{c\bar{c}}$ being only 1: (a) $J=min(J_\ell)-1$ or $J=max(J_\ell)+1$; (b)…
The experimental signature of an S=+1 baryon of mass 1540 MeV and width 10-25 MeV has led to speculation that this is an exotic baryon consisting of 4 quarks and 1 antiquark lying at the top of a $\bar{10}$ SU(3) multiplet. The observed…
Recent experimental evidence for the Theta^+(1540) has given rise to much theoretical interest in exotic baryons. The Theta^+ is a baryon that has strangeness S=+1, meaning that it contains an anti-strange quark. Thus it cannot be…
A model recently introduced by Jaffe and Wilczek based on the quarks being dynamically bound into diquarks has been used to predict that the recently observed exotic baryons (pentaquarks) fall into a nearly ideally mixed combination of an…
The 1/N expansion for exotic baryons is developed, and applied to the masses, meson couplings and decay widths. Masses and widths of the 27 and 35 pentaquark states in the same tower as the Theta+ are related by spin-flavor symmetry. The 27…
It is shown, that the small decay width of $\Theta^+ = uudd\bar{s}$ baryon is suppressed by chirality violation. It is shown that $\Theta^+$ decay width $\Gamma$ is proportional to $\alpha^2_s < 0 | \bar{q} q | 0 >^2$, for any pentaquark…
We study the selfenergy of the $\Theta^+$ pentaquark in nuclei associated with two types of interaction: the KN decay of the $\Theta^+$ and two meson baryon decay channels of the $\Theta^+$. Whereas the potential related to the first source…
We review the current status of the exotic pentaquark baryons. After a brief look at experiments of both positive and negative results, we discuss theoretical methods to study the structure and reactions for the pentaquarks. First we…
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…