We performed a search for a light pseudoscalar particle X in the decay KL0→π0π0X, X→γγ with the E391a detector at KEK. Such a particle with a mass of 214.3MeV/c2 was suggested by the HyperCP experiment. We found no evidence for X and set an upper limit on the product branching ratio for KL0→π0π0X, X→γγ of 2.4×10-7 at the 90% confidence level. Upper limits on the branching ratios in the mass region of X from 194.3 to 219.3MeV/c2 are also presented.
ASJC Scopus subject areas
- General Physics and Astronomy