Pentaquark Theta+, constituent quark structures, and prediction of charmed Theta(c)^0 and bottomed Theta(b)^+

Abstract

The newly observed ${\Theta }^{+}$ resonance is believed to be a pentaquark with the constituent quarks $uudd\bar{s}$. There are a few options for the constituent quark structure. Some advocate diquark-diquark-antiquark $(ud)$-$(ud)$-$\bar{s}$ while others favor diquark-triquark $(ud)$-$(ud\bar{s})$. We use the color-spin hyperfine interaction to examine the energy levels of these structures, and we find that the diquark-diquark-antiquark structure is slight favored. We proceed to write down the flavor triplet and antisextet of the charmed or bottomed exotic baryons with internal $qqqq\bar{Q}$ quarks. We also estimate the mass of ${\Theta }_c^0$ and ${\Theta }_b^{+}$.

Comments: Revtex 4, 7 pages, the published version, one reference is corrected