The anticharmed exotic baryon Θ c and its relatives

Motivated by the recent discovery of the exotic S = +1 narrow baryon resonance Θ+ at 1540 MeV, with quark content uud ds̄, we conjecture the existence of its anti-charmed analogue Θcwith quark content uuddc̄, and compute its likely properties. We rely on the recently constructed model of a novel kind of a pentaquark with an unusual color structure which provides a good approximation to the Θ+ mass. We expect that Θc is an isosinglet with J P = 1 2 − and estimate its mass at 2985± 50 MeV. We also discuss another possible exotic baryon resonance containing heavy quarks, the Θb , a uuddb̄ state, and estimate m Θ+b = 6398±50 MeV. These states should appear as unexpectedly narrow peaks in D−p, D̄0n, B0p and B+n mass distributions. ∗e-mail: [email protected] †e-mail: [email protected]