Search for Theta+ via pi- p --> K- X reaction near production threshold

Abstract

We have searched for ${\Theta }^{+}$ via ${\pi }^{-}p\to K^{-}X$ reaction using 1.87 and 1.92 GeV/c ${\pi }^{-}$ beam at the K2 beam line of the KEK 12 GeV Proton Synchrotron. In the missing mass spectrum at beam momentum of 1.92 GeV/$c$, a bump has been found at 1530 MeV/$c^2$ which is consistent with the mass reported by several experiments. The statistical significance of this bump, however, is only 2.5$-2.7\sigma$. Therefore we have derived the upper limit of ${\Theta }^{+}$ production cross section via ${\pi }^{-}p\to K^{-}{\Theta }^{+}$ reaction which is 4.3$\mu$b at 90% confidence level assuming that ${\Theta }^{+}$ is produced isotropically in the center of mass system.

arXiv comment12pages, 6figures, to be published in Physics Letters B

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• Improved study of a possible Theta+ production in the pp -> p K0 sigma+ reaction with the COSY-TOF spectrometer
• Search for Theta+ via K+p -> pi+X reaction with a 1.2 GeV/c K+ beam
• Present status on experimental search for pentaquarks
• High-resolution search for the ${\Theta }^{+}$ pentaquark via a pion-induced reaction at J-PARC
• Axial-vector transitions and strong decays of the baryon antidecuplet in the self-consistent SU(3) chiral quark-soliton model
• Theta+ formation in inclusive gamma D -> pK- X
• Quark spin content of the proton, hyperon semileptonic decays, and the decay width of the ${\Theta }^{+}$ pentaquark
• Spin-3/2 Pentaquark in QCD Sum Rules
• Feasibility study of the $K^{+}d\to K^{0}pp$ reaction for the "${\Theta }^{+}$" pentaquark
• Mass splittings of the baryon decuplet and antidecuplet with the second-order flavor symmetry breakings within a chiral soliton model
• Electric properties of the baryon anti-decuplet in the SU(3) chiral quark-soliton model
• Positive parity pentaquark towers in large Nc QCD
• Pentaquark Theta^+ production via gamma N ->K^*bar Theta^+(3/2^(+-))
• Magnetic and axial-vector transitions of the baryon antidecuplet
• $N^{\ast }$ states with hidden charm and a three-body nature
• Photoproduction of Theta^+(1540,1/2^+) reexamined with new theoretical information
• Photoproduction of the Theta^+ and its vector and axial-vector structure