Evidence for an Exotic S = -2, Q = -2 Baryon Resonance in Proton-Proton Collisions at the CERN SPS

(NA49 Collaboration) Alt, C; Anticic, T; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Christakoglou, P; Chvala, O; Cramer, JG; Csato, P; Darmenov, N; Dimitrov, A; Dinkelaker, P; Eckardt, V; Farantatos, G; Filip, P; Flierl, D; Fodor, Z; Foka, P; Freund, P; Friese, V; Gal, J; Gazdzicki, M; Georgopoulos, G; Gladysz, E; Hegyi, S; Hohne, C; Kadija, K; Karev, A; Kniege, S; Kolesnikov, VI; Kollegger, T; Korus, R; Kowalski, M; Kraus, I; Kreps, M; van Leeuwen, M; Levai, P; Litov, L; Makariev, M; Malakhov, AI; Markert, C; Mateev, M; Mayes, BW; Melkumov, GL; Meurer, C; Mischke, A; Mitrovski, M; Molnar, J; Mrowczynski, S; Palla, G; Panagiotou, AD; Panayotov, D; Perl, K; Petridis, A; Pikna, M; Pinsky, L; Puhlhofer, F; Reid, JG; Renfordt, R; Retyk, W; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Sann, H; Schmitz, N; Seyboth, P; Sikler, F; Sitar, B; Skrzypczak, E; Stefanek, G; Stock, R; Strobele, H; Susa, T; Szentpetery, I; Sziklai, J; Trainor, TA; Varga, D; Vassiliou, M; Veres, GI; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Yoo, IK; Zaranek, J; Zimanyi, J; (2004) Evidence for an Exotic S = -2, Q = -2 Baryon Resonance in Proton-Proton Collisions at the CERN SPS. Physical Review Letters, 92 (4). 042003/1-042003/5. ISSN 0031-9007

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Official URL: http://journals.aps.org/prl/abstract/10.1103/PhysR...

Abstract

Results of resonance searches in the Ξ−π−, Ξ−π+, Ξ¯¯¯+π−, and Ξ¯¯¯+π+ invariant mass spectra in proton-proton collisions at s√=17.2 GeV are presented. Evidence is shown for the existence of a narrow Ξ−π− baryon resonance with mass of 1.862±0.002 GeV/c2 and width below the detector resolution of about 0.018 GeV/c2. The significance is estimated to be above 4.2σ. This state is a candidate for the hypothetical exotic Ξ−−3/2 baryon with S=−2, I=32, and a quark content of (dsdsu¯). At the same mass, a peak is observed in the Ξ−π+ spectrum which is a candidate for the Ξ03/2 member of this isospin quartet with a quark content of (dsusd¯). The corresponding antibaryon spectra also show enhancements at the same invariant mass.

Item Type:

Article

Uncontrolled Keywords:

exotic; pentaquark; NA49; p+p

Subjects:

NATURAL SCIENCES > Physics

Divisions:

Division of Experimental Physics

Projects: