Anti-charmed pentaquark from B decays

Abstract

We explore the possibility of observing the anti-charmed pentaquark state from the ${\Theta }_c\bar{n}{\pi }^{+}$ decay of $B$ meson produced at $B$-factory experiments. We first show that the observed branching ratio of the $B^{+}$ to ${\Lambda }_c^{-}p{\pi }^{+}$, as well as its open histograms, can be remarkably well explained by assuming that the decay proceeds first through the ${\pi }^{+}{\bar{D}}^0$ (or ${\bar{D}}^{\ast 0}$) decay, whose branching ratios are known, and then through the subsequent decay of the virtual ${\bar{D}}^0$ or ${\bar{D}}^{\ast 0}$ mesons to ${\Lambda }_c^{-}p$, whose strength are calculated using previously fit hadronic parameters. We then note that the ${\Theta }_c$ can be similarly produced when the virtual ${\bar{D}}^0$ or ${\bar{D}}^{\ast 0}$ decay into an anti-nucleon and a ${\Theta }_c$. Combining the present theoretical estimates for the ratio $g_{DN{\Lambda }_c}/g_{DN{\Theta }_c}\sim 13$ and $g_{D^{\ast }N{\Theta }_c}\sim 1/3g_{DN{\Theta }_c}$, we find that the anti-charmed pentaquark ${\Theta }_c$, which was predicted to be bound by several model calculations, can be produced via $B^{+}\to {\Theta }_c\bar{n}{\pi }^{+}$, and be observed from the $B$-factory experiments through the weak decay of ${\Theta }_c\to p{K}^{+}{\pi }^{-}{\pi }^{-}$.

Comments: 4 pages, 4 figures, Revised version to be published in Physical Review Letters