engleski

Exotic Cascades at NA49

The results of resonance searches in Xi-pi-, Xi-pi+, bar{;Xi};+pi- and bar{;Xi};+pi+ invariant mass spectra in proton-proton collisions at sqrt{;s};=17.2 GeV are presented. A narrow state was observed in Xi-pi- spectra with mass of 1.862 +- 0.002 GeV/c2 and width below the detector resolution of about 0.018 GeV/c2. This state is identified as a candidate for the hypothesized exotic Xi5-- baryon with S = -2, I=3/2 and a quark content of (dsds bar{;u};). Xi-pi+ and the corresponding antiparticle spectra show an indication of enhancements at the same mass. Very preliminary results of resonance search in pKS0 channel show a resonant structure at 1.526 GeV/c2.

CERN; NA49; pentaquark; exotic particles

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