Recent Results on Searches for Pentaquark States from STAR at RHIC

الأصل · EN

We present results on pentaquark searches from nuclear collisions at RHIC with the STAR detector system. An intriguing peak has been observed in the invariant mass distribution of pK⁺+pK⁻ from 18.6 Million d+Au collision events at √sNN = 200 GeV. The peak centers at a mass 1528 ± 2 ± 5 MeV/c² and the FWHM 15 MeV/c² limited by detector responses. The statistical significance of the peak is 4.2σ. Such a state if confirmed is manifestly exotic and implies a family of isospin one states. A weak signal of less statistical significance (3σ) has been observed in 5.6M Au+Au collision events at 62.4 GeV. Searches in 10.7M Au+Au collision events at 200 GeV yield no significant signal. The Au+Au results neither confirm nor rule out the d+Au observation as a possible state.