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Search for the Theta+ pentaquark in the reactions gammap-->[overline K]0K+n and gammap-->[overline K]0K0p

Journal Article · · Physical Review, D (Particles Fields)
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The exclusive reactions {gamma}p {yields} {bar K}{sup 0} K{sup +} n and {gamma}p {yields} {bar K}{sup 0} K{sup 0} p have been studied in the photon energy range 1.6--3.8 GeV, searching for evidence of the exotic baryon {Theta}{sup +}(1540) in the decays {Theta}{sup +} {yields} nK{sup +} and {Theta}{sup +} {yields} pK{sup 0}. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The integrated luminosity was about 70 pb{sup -1}. The reactions have been isolated by detecting the K{sup +} and proton directly, the neutral kaon via its decay to K{sub S} {yields} {pi}{sup +}{pi}{sup -} and the neutron or neutral kaon via the missing mass technique. The mass and width of known hyperons such as {Sigma}{sup +}, {Sigma}{sup -} and {Lambda}(1116) were used as a check of the mass determination accuracy and experimental resolution. Approximately 100,000 {Lambda}*(1520)'s and 150,000 {phi}'s were observed in the {bar K}{sup 0} K{sup +} n and {bar K}{sup 0} K{sup 0} p final state respectively. No evidence for the {Theta}{sup +} pentaquark was found in the nK{sup +} or pK{sub S} invariant mass spectra. Upper limits were set on the production cross section of the reaction {gamma}p {yields} {Theta}{sup +} {bar K}{sup 0} as functions of center-of-mass angle, nK{sup +} and pK{sub 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}{sup +} width, {Gamma}{sub {Theta}{sup +}}, ranging between 0.01 and 7 MeV.
Research Organization:
Thomas Jefferson National Accelerator Facility, Newport News, VA
Sponsoring Organization:
USDOE - Office of Energy Research (ER)
DOE Contract Number:
AC05-84ER40150
OSTI ID:
895075
Report Number(s):
JLAB-PHY-06-544; DOE/ER/40150-4133; hep-ex/0606062
Journal Information:
Physical Review, D (Particles Fields), Journal Name: Physical Review, D (Particles Fields) Vol. 74; ISSN PRVDAQ; ISSN 0556-2821
Country of Publication:
United States
Language:
English

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Related Subjects

43 PARTICLE ACCELERATORS
ACCURACY
BARYONS
CEBAF ACCELERATOR
CROSS SECTIONS
DECAY
ENERGY RANGE
HYPERONS
KAONS
LUMINOSITY
MASS SPECTRA
MESONS
MISSING MASS
NEUTRONS
PHOTONS
PROTONS
TOTAL CROSS SECTIONS