New limits on exotic two-body decay of orthopositronium

Journal Article · Mon Aug 07 04:00:00 EDT 1989 · Phys. Rev. Lett.; (United States)

DOI:https://doi.org/10.1103/PhysRevLett.63.597· OSTI ID:5891166

Orito, S; Yoshimura, K; Haga, T; Minowa, M; Tsuchiaki, M

Motivated by the recently reported discrepancy between measured and theoretical values for the orthopositronium lifetime, we have searched for exotic decay of orthopositronium into /gamma/ plus a long-lived neutral particle /ital X/, in the hitherto unexplored mass region of /ital m//sub /ital x// below 100 keV. Our negative result provides new upper limits of 6.4/times/10/sup /minus/5/ to 7.6/times/10/sup /minus/6/ on the branching ratio of such decay. Consequently we exclude the hypothesis of Samuel, i.e., that a new pseudoscalar particle with mass less than 5.7 keV is responsible for the discrepancy of the orthopositronium lifetime.

• Research Organization: Department of Physics, Faculty of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113, Japan (JP)
• OSTI ID: 5891166
• Journal Information: Phys. Rev. Lett.; (United States), Journal Name: Phys. Rev. Lett.; (United States) Vol. 63:6; ISSN PRLTA
• Country of Publication: United States
• Language: English

Related Subjects

640303 -- Atomic
Molecular & Chemical Physics-- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules
645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METAL COMPOUNDS
BOSONS
BRANCHING RATIO
CALIBRATION
CESIUM COMPOUNDS
CESIUM IODIDES
COINCIDENCE METHODS
COUNTING TECHNIQUES
DATA
DATA ACQUISITION SYSTEMS
DECAY
ELEMENTARY PARTICLES
ENERGY RANGE
EXPERIMENTAL DATA
GAMMA SPECTRA
HADRONS
HALIDES
HALOGEN COMPOUNDS
INFORMATION
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
KEV RANGE
KEV RANGE 10-100
KEV RANGE 100-1000
LIFETIME
MEASURING INSTRUMENTS
MESONS
NUMERICAL DATA
PARTICLE IDENTIFICATION
PHOSPHORS
PLASTIC SCINTILLATORS
POSITRONIUM
PSEUDOSCALAR MESONS
RADIATION DETECTORS
SEMICONDUCTOR DETECTORS
SPECTRA