tau. decay puzzle

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.45.R721· OSTI ID:7277581

Marciano, W J ^[1]

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1. Brookhaven National Laboratory, Upton, New York 11973 (United States)

Directly measured {tau} decay branching ratios {ital B}({tau}{r arrow}{ital e}{nu}{bar {nu}}), {ital B}({tau}{r arrow}{mu}{nu}{bar {nu}}), {ital B}({tau}{r arrow}{nu}{sub {tau}}{pi}/{ital K}), and {ital B}({tau}{r arrow}{nu}{sub {tau}}{pi}{sup {minus}}{pi}{sup 0}) are compared with standard-model predictions parametrized in terms of the {tau} mass and lifetime. For current averages, {ital m}{sub {tau}}=1784.1{sub {minus}3.6}{sup +2.7} MeV and {tau}{sub {tau}}=3.04{plus minus}0.07{times}10{sup {minus}13} s, the experimental branching ratios are found to be systematically, smaller than theory, thereby suggesting that significant reductions in the {tau} lifetime or mass (perhaps both) are likely. If {tau}{sub {tau}} and {ital m}{sub {tau}} correct, a heavy fourth-generation neutrino with {ital m}{sub {nu}4}{approx gt}45.3 GeV and mixing sin{sup 2}{theta}{sub 34}{congruent}0.06 could be the source of the discrepancy.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 7277581
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 45:3; ISSN PRVDA; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

662370* -- Decays of Leptons-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANTILEPTONS
ANTIMATTER
ANTINEUTRINOS
ANTIPARTICLES
BOSONS
BRANCHING RATIO
CORRECTIONS
DECAY
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEAVY LEPTONS
LEPTONS
LIFETIME
MASS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MATTER
MESONS
MUONS
NEUTRINOS
PARTICLE DECAY
PARTICLE MODELS
PARTICLE PRODUCTION
PIONS
PIONS MINUS
PIONS NEUTRAL
POSTULATED PARTICLES
PSEUDOSCALAR MESONS
RADIATIVE CORRECTIONS
STANDARD MODEL
TAU PARTICLES
UNIFIED GAUGE MODELS