The quark model does not exclude states composed of more than three quarks, like pentaquark systems. Controversial evidence for such states has been published in the last years, in particular: for a strange pentaquark Θ (1540)+; for a double-strange state, the Ξ (1862)- -, subsequently called Φ (1860)- -; and for a charmed state, the Θc (3100)0. If confirmed, a full pentaquark family might exist; such pentaquark states could be produced in e+ e- annihilations near the Z energy. In this Letter a search for pentaquarks is described using the DELPHI detector at LEP, characterized by powerful particle identification sub-systems crucial in the separation of the signal from the background for these states. At 95% CL, upper limits are set on the production rates 〈 N 〉 of such particles and their charge-conjugate state per Z decay: 〈 NΘ+ 〉 × Br (Θ+ → p KS0) < 5.1 × 10-4, 〈 NΘ+ + 〉 < 1.6 × 10-3, 〈 NΦ (1860)- - 〉 × Br (Φ (1860)- - → Ξ- π-) < 2.9 × 10-4, 〈 NΘc (3100)0 〉 × Br (Θc (3100)0 → D* + over(p, ̄)) < 8.8 × 10-4. © 2007 Elsevier B.V. All rights reserved.

Abdallah, J., Abreu, P., Adam, W., Adzic, P., Albrecht, T., Alemany Fernandez, R., et al. (2007). Search for pentaquarks in the hadronic decays of the Z boson with the DELPHI detector at LEP. PHYSICS LETTERS. SECTION B, 653(2-4), 151-160 [10.1016/j.physletb.2007.08.005].

Search for pentaquarks in the hadronic decays of the Z boson with the DELPHI detector at LEP

CALVI, MARTA;PAGANONI, MARCO;TABARELLI DE FATIS, TOMMASO;
2007

Abstract

The quark model does not exclude states composed of more than three quarks, like pentaquark systems. Controversial evidence for such states has been published in the last years, in particular: for a strange pentaquark Θ (1540)+; for a double-strange state, the Ξ (1862)- -, subsequently called Φ (1860)- -; and for a charmed state, the Θc (3100)0. If confirmed, a full pentaquark family might exist; such pentaquark states could be produced in e+ e- annihilations near the Z energy. In this Letter a search for pentaquarks is described using the DELPHI detector at LEP, characterized by powerful particle identification sub-systems crucial in the separation of the signal from the background for these states. At 95% CL, upper limits are set on the production rates 〈 N 〉 of such particles and their charge-conjugate state per Z decay: 〈 NΘ+ 〉 × Br (Θ+ → p KS0) < 5.1 × 10-4, 〈 NΘ+ + 〉 < 1.6 × 10-3, 〈 NΦ (1860)- - 〉 × Br (Φ (1860)- - → Ξ- π-) < 2.9 × 10-4, 〈 NΘc (3100)0 〉 × Br (Θc (3100)0 → D* + over(p, ̄)) < 8.8 × 10-4. © 2007 Elsevier B.V. All rights reserved.
Articolo in rivista - Articolo scientifico
Nuclear and High Energy Physics
English
151
160
10
Abdallah, J., Abreu, P., Adam, W., Adzic, P., Albrecht, T., Alemany Fernandez, R., et al. (2007). Search for pentaquarks in the hadronic decays of the Z boson with the DELPHI detector at LEP. PHYSICS LETTERS. SECTION B, 653(2-4), 151-160 [10.1016/j.physletb.2007.08.005].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/155905
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