First observation of γ γ →p p ¯K+K- and search for exotic baryons in p K systems
Abstract
The process γ γ →p p ¯ K+K- and its intermediate processes are measured for the first time using a 980 fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The production of p p ¯K+K- and a Λ (1520 )0 (Λ ¯ (1520 )0) signal in the p K- (p ¯K+) invariant mass spectrum are clearly observed. However, no evidence for an exotic baryon near 1540 MeV /c2 , denoted as Θ (1540 )0 (Θ ¯(1540 )0) or Θ (1540 )++ (Θ (1540 )--), is seen in the p K- (p ¯K+) or p K+ (p ¯K-) invariant mass spectra. Cross sections for γ γ →p p ¯K+K-, Λ (1520 )0p ¯ K++c .c . and the products σ (γ γ →Θ (1540 )0p ¯ K++c .c .)B (Θ (1540 )0→p K-) and σ (γ γ →Θ (1540 )++p ¯ K-+c .c .)B (Θ (1540 )++→p K+) are measured. We also determine upper limits on the products of the χc 0 and χc 2 two-photon decay widths and their branching fractions to p p ¯ K+K- at the 90% credibility level.
- Publication:
-
Physical Review D
- Pub Date:
- June 2016
- DOI:
- 10.1103/PhysRevD.93.112017
- Bibcode:
- 2016PhRvD..93k2017S