Anti-charmed pentaquark ${\Theta }_c(3099)$ from QCD sum rules

Abstract

We construct QCD sum rules for the anti-charmed pentaquark ${\Theta }_c(3099)$, recently reported at HERA. The sum rules are constructed similarly with the ${\Theta }^{+}(1540)$ sum rules using the anti-charmed analogue of the ${\Theta }^{+}$ interpolating field. The strange quark and quark-gluon mixed condensates, which were important in the ${\Theta }^{+}$ sum rules, are replaced by the gluon condensates whose contribution to the OPE is suppressed due to the heavy quark mass. Our result suggests that the parity of ${\Theta }_c$ is positive. We identify the difference from the ${\Theta }^{+}$ sum rule, which leads to the positive parity in this heavy-light pentaquark system. The obtained mass is similar to the experimental value.

Comments: 10 pages, the revised version to appear in PLB