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

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• 作者：J. Abdallah ; P. Abreu ; W. Adam ; P. Adzic ; T. Albrecht ; R. Alemany-Fern ; ez ; T. Allmendinger ; P.P. Allport ; U. Amaldi ; N. Amapane ; S. Amato ; E. Anashkin ; A. Andreazza ; S. Andringa ; N. Anjos ; P. Antilogu
• 关键词：Kaon decays ; Semileptonic decays ; Test of Standard Model
• 刊名：Physics Letters B
• 出版年：2007
• 出版时间：20 September 2007
• 年：2007
• 卷：653
• 期：2-4
• 页码：151-160
• 全文大小：337 K

文摘

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 di=B6TVN-4PC3SBV-6&_mathId=mml11&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=046258eb8331d6357d3b2f6a4ca73551"" title=""Click to view the MathML source"">Θ(1540)⁺; for a double-strange state, the di=B6TVN-4PC3SBV-6&_mathId=mml12&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=a4382ae2c3d1e4dfae9a0a1d1bd22ebb"" title=""Click to view the MathML source"">Ξ(1862)⁻⁻, subsequently called di=B6TVN-4PC3SBV-6&_mathId=mml13&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=4ec0f9be74f756333ad65242fc9761fc"" title=""Click to view the MathML source"">Φ(1860)⁻⁻; and for a charmed state, the di=B6TVN-4PC3SBV-6&_mathId=mml14&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=9926aab20e9090769edbb0dffdbbaf0f"" title=""Click to view the MathML source"">Θ_c(3100)⁰. If confirmed, a full pentaquark family might exist; such pentaquark states could be produced in di=B6TVN-4PC3SBV-6&_mathId=mml15&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=cf712c713394e4637e3461b3e7e016f1"" title=""Click to view the MathML source"">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 di=B6TVN-4PC3SBV-6&_mathId=mml16&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=3685b5a1b7e84f86f7133ae9820d8e21"" title=""Click to view the MathML source"">direct.com/scidirimg/entities/2329.gif"" alt=""left angle bracket"" border=0>Ndirect.com/scidirimg/entities/232a.gif"" alt=""right-pointing angle bracket"" border=0> of such particles and their charge-conjugate state per Z decay: di=B6TVN-4PC3SBV-6&_mathId=mml17&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=c16b5014eae6bb709c1989be2eba4259"">direct.com/cache/MiamiImageURL/B6TVN-4PC3SBV-6-1P/0?wchp=dGLzVlz-zSkzk"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=20 width=261>, di=B6TVN-4PC3SBV-6&_mathId=mml18&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=4154983b3b8ed74fc4e6f1fb71497edf"" title=""Click to view the MathML source"">direct.com/scidirimg/entities/2329.gif"" alt=""left angle bracket"" border=0>N_Θ⁺⁺direct.com/scidirimg/entities/232a.gif"" alt=""right-pointing angle bracket"" border=0><1.6×10⁻³, di=B6TVN-4PC3SBV-6&_mathId=mml19&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=5d542b17c45a503f015b7b36b4ec3de0"" title=""Click to view the MathML source"">direct.com/scidirimg/entities/2329.gif"" alt=""left angle bracket"" border=0>N_{Φ(1860)⁻⁻}direct.com/scidirimg/entities/232a.gif"" alt=""right-pointing angle bracket"" border=0>×Br(Φ(1860)⁻⁻→Ξ⁻π⁻)<2.9×10⁻⁴, di=B6TVN-4PC3SBV-6&_mathId=mml20&_user=10&_cdi=5539&_rdoc=8&_acct=C000050221&_version=1&_userid=10&md5=11a83bf091718dfa918d91270115f262"">direct.com/cache/MiamiImageURL/B6TVN-4PC3SBV-6-2/0?wchp=dGLzVlz-zSkzk"" alt=""Click to view the MathML source"" align=""absbottom"" border=""0"" height=22 width=350>.