An Investigation Of The P Dependence Of The Cross Section And Invariant Mass Spectrum Of The Reaction P N E E X Inclusive In The Region Of 2 To 4 Gev

Author : Manabu Moritsu
Publisher : Springer
ISBN 13 : 9811000123
Total Pages : 132 pages
Book Rating : 4.8/5 (11 download)

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Download or read book Search for the Pentaquark Θ+ via the π−p → K−X Reaction at J-PARC written by Manabu Moritsu and published by Springer. This book was released on 2016-02-17 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: This theses reports on an experimental search for an exotic hadron, Θ+(1540) pentaquark, which is a genuine exotic hadron with a five-quark system of uuddsbar. The results of this book support that the existence of Θ+ was strongly constrained. The Θ+ pentaquark was searched for via the π- p → K- X reaction using a beam momentum of 2.01 GeV/c at the J-PARC hadron experimental facility, taking advantage of high-statistics and high-resolution compared with previous experiments, some of which claimed the evidence of Θ+. In order to realize a good missing-mass resolution of 2 MeV, the beam spectrometer and superconducting kaon spectrometer were constructed. No clear peak was observed in the missing mass spectrum of the π- p → K- X reaction, and the upper limit of the production cross section was found to be less than 0.28 μb/sr at the 90% confidence level in a mass region of 1500–1560 MeV/c2. This upper limit is an order of magnitude smaller than that of the previous KEK experiment. Compared with a theoretical calculation using the effective Lagrangian approach, the decay width of Θ+ was evaluated. The upper limits on the decay width were estimated to be 0.36 and 1.9 MeV for the Θ+ spin-parity of 1/2+ and 1/2-, respectively. These are quite small for a width of ordinary hadron resonances, and the existence of Θ+ was strongly constrained and is doubtful.