Search for nucleon decay into lepton and K/sup 0/

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5796132

Cortez, B G

Recent grand unification theory predictions of nucleon lifetimes of 10/sup 29/ to 10/sup 32/ years motivated the current search for nucleon decay. The 8 kt Irvine-Michigan-Brookhaven water Cherenkov ring-imaging detector was constructed 2000 feet underground, in an environment shielded from cosmic ray background, to detect the products of proton decay. The unique characteristics of the detector are its large mass, totally active volume, isotropic detection efficiency, and ability to unambiguously determine the sense of track direction. The detector utilizes a custom made photomultiplier readout system and a laser based calibration system to convert Cherenkov light yields to particle tracks and energies. Operation of the detector over a lifetime of 130 days has provided 112 observed events in a fiducial volume of 3.3 kt. These events are consistent in rate, energy, and direction with the expected cosmic ray neutrino interactions. The search for nucleon decay into final states with a lepton and K/sub 0/ has produced candidates which are consistent with the expected background from neutrino interactions. There are candidates for two of the channels, i.e., two possible candidates for ..mu../sup +/K/sup 0/ and three possible candidates for nuK/sub 0/. The following limits on the nucleon lifetime over branching ratio can be set at the 90% CL: (1) tau/B (p ..-->.. ..mu../sup +/K/sup 0/) > 2.6 x 10/sup 31/ years; (2) tau/B (n ..-->.. nuK/sup 0/) > 0.8 x 10/sup 31/ years and (3) tau/B (p ..-->.. e/sup +/K/sup 0/) > 3.1 x 10/sup 31/ years. These three experimental limits are evidence against Higgs dominated SU(5) theories, supersymmetric decay theories, and gravitationally induced supersymmetric theories, respectively.

• Research Organization: Harvard Univ., Boston, MA (USA)
• OSTI ID: 5796132
• Country of Publication: United States
• Language: English

Related Subjects

645102* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Weak Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BARYONS
BOSONS
BRANCHING RATIO
CHERENKOV COUNTERS
DATA
DECAY
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HADRONS
INFORMATION
KAONS
KAONS NEUTRAL
LEPTONS
LIFETIME
LIMITING VALUES
MASSLESS PARTICLES
MEASURING INSTRUMENTS
MESONS
MUONS
MUONS PLUS
NEUTRINOS
NEUTRONS
NUCLEONS
NUMERICAL DATA
PARTICLE DECAY
POSITRONS
PROTONS
PSEUDOSCALAR MESONS
RADIATION DETECTORS
SEMILEPTONIC DECAY
SPACE
STRANGE MESONS
STRANGE PARTICLES
UNDERGROUND SPACE
WEAK PARTICLE DECAY