Search for the Pentaquark Θ+ via the π−p → K−X Reaction at J-PARC

von Manabu Moritsu

123 Seiten, Hardcover

Kurzbeschreibung des Verlags

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 uudds
bar
. 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/c
2
. 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.

• Reihe: Springer Theses
• ISBN: 9789811000102
• Sprache: Englisch
• Erscheinungsdatum: 02.03.2016
• Genre: Physik, Astronomie/Atomphysik, Kernphysik
• Verlag: Springer Singapore