Search for the ${\Theta }^{+}$ pentaquark in the reactions $\gamma p\to {\bar{K}}^0{K}^{+}n$ and $\gamma p\to {\bar{K}}^0{K}^{0}p$

Abstract

The exclusive reactions $\gamma p\to {\bar{K}}^0{K}^{+}n$ and $\gamma p\to {\bar{K}}^0{K}^{0}p$ have been studied in the photon energy range 1.6--3.8 GeV, searching for evidence of the exotic baryon ${\Theta }^{+}(1540)$ in the decays ${\Theta }^{+}\to n{K}^{+}$ and ${\Theta }^{+}\to p{K}^0$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The integrated luminosity was about 70 pb${}^{-1}$. The reactions have been isolated by detecting the $K^{+}$ and proton directly, the neutral kaon via its decay to $K_S\to {\pi }^{+}{\pi }^{-}$ and the neutron or neutral kaon via the missing mass technique. The mass and width of known hyperons such as ${\Sigma }^{+}$, ${\Sigma }^{-}$ and $\Lambda (1116)$ were used as a check of the mass determination accuracy and experimental resolution. Approximately 100,000 ${\Lambda }^{\ast }(1520)$'s and 150,000 $\varphi$'s were observed in the ${\bar{K}}^0{K}^{+}n$ and ${\bar{K}}^0{K}^{0}p$ final state respectively. No evidence for the ${\Theta }^{+}$ pentaquark was found in the $n{K}^{+}$ or $p{K}_S$ invariant mass spectra. Upper limits were set on the production cross section of the reaction $\gamma p\to {\Theta }^{+}{\bar{K}}^0$ as functions of center-of-mass angle, $n{K}^{+}$ and $p{K}_S$ masses. Combining the results of the two reactions, the 95% C.L. upper limit on the total cross section for a resonance peaked at 1540 MeV was found to be 0.7 nb. Within most of the available theoretical models, this corresponds to an upper limit on the ${\Theta }^{+}$ width, ${\Gamma }_{{\Theta }^{+}}$, ranging between 0.01 and 7 MeV.

arXiv comment1 tex file (16 pages) + 23 figures (25 eps files)

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Cited by in corpus (35)

• Studying Exotic Hadrons in Heavy Ion Collisions
• Evidence of the Θ^+ in the γd \to K^+K^-pn reaction
• Nuclear-bound quarkonia and heavy-flavor hadrons
• $\varphi$-meson photoproduction on Hydrogen in the neutral decay mode
• Near-threshold photoproduction of $\Lambda (1520)$ from protons and deuterons
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• Cross sections for the $\gamma p\to K^{\ast +}\Lambda$ and $\gamma p\to K^{\ast +}{\Sigma }^0$ reactions measured at CLAS
• Present status on experimental search for pentaquarks
• Near-threshold Photoproduction of Phi Mesons from Deuterium
• Quantum chromodynamics quark benzene
• An explanation why the Theta+ is seen in some experiments and not in others
• Axial-vector transitions and strong decays of the baryon antidecuplet in the self-consistent SU(3) chiral quark-soliton model
• A possible explanation why the Theta+ is seen in some experiments and not in others
• Quantum interference of particles and resonances
• Vector transition form factors of the $N{K}^{\ast }\to {\Theta }^{+}$ and $N{\bar{K}}^{\ast }\to {\Sigma }_{\overline{10}}^{\ast -}$ in the SU(3) chiral quark-soliton model
• Theta+ formation in inclusive gamma D -> pK- X
• Search for ${\Theta }^{++}$ Pentaquarks in the Exclusive Reaction $\gamma p\to K^{+}{K}^{-}p$
• To see the exotic Theta^+ baryon from interference
• Exotic hadrons and hadron-hadron interactions in heavy ion collisions
• K*-couplings for the antidecuplet excitation
• Photoproduction of $K^{+}{K}^{-}$ meson pairs on the proton
• On strange SU(3) partners of Theta+
• Kaon-Deuteron Scattering at Low Energies
• Possible quantum numbers of the pentaquark Θ^+(1540) in QCD sum rules
• Spectral-fluctuations test of the quark-model baryon spectrum
• 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
• Systematic study of pentaquark states: $qqq-q\bar{q}$ configuration
• Positive parity pentaquark towers in large Nc QCD
• Exotic in dense and cold nuclear matter
• Vector and axial-vector structures of the Theta^+
• Photoproduction of the Theta^+ and its vector and axial-vector structure
• Photoproduction of Theta^+(1540,1/2^+) reexamined with new theoretical information
• Lattice QCD study of a five-quark hadronic molecule