General theory of weak processes involving neutrinos. II. Pure leptonic decays

Journal Article · Tue Sep 01 00:00:00 EDT 1981 · Phys. Rev. D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.24.1275· OSTI ID:6149495

Shrock, R E

We present a general theory of leptonic decays which consistently incorporates the possibility of nonzero neutrino masses and associated lepton mixing. We calculate the differential decay distribution d/sup 2/GAMMA/dE/sub b/d costheta and the l/sub b/ polarization for ''the'' decay l/sub a/..--> nu../sub l//sub a/l/sub b/nu-bar/sub l//sub b/, i.e., in general the incoherent sum of decays l/sub a/..--> nu../sub i/l/sub b/nu-bar/sub j/ into all allowed mass eigenstates ..nu../sub i/ and nu-bar/sub j/. Expressions are also given for the average quantities (E/sub b/), (integrated over E/sub b/), (..beta..), and for individual (i,j) decay modes and the observed sum. The total rate for massive-neutrino modes is calculated for the relevant experimental cases. These results are applied to analyze what the observable characteristics of massive neutrinos and lepton mixing would be in leptonic l/sub a/ decay. We show that dGAMMA/dE/sub b/ would in general contain kinks at intermediate energies and carry out a search for these in existing ..mu.. and tau decay data. We further show that the conventional determination of the Lorentz structure of weak leptonic couplings via measurement of the spectral parameters rho, eta, xi, and delta is not applicable in the presence of massive neutrinos and lepton mixing; a deviation of the observed parameters (with radiative corrections extracted) from their conventional V-A values could be caused either by non-(V-A) Lorentz structure or by massive-neutrino decay modes and lepton mixing. Thus, past measurements of the spectral parameters yield information only on the combined effects of the underlying Lorentz structure of the couplings and on possible neutrino masses and mixing, but not on either of these in isolation. The appropriate generalized formalism for the analysis of Lorentz structure in leptonic decays is given.

• Research Organization: Institute for Theoretical Physics, State University of New York at Stony Brook, Stony Brook, New York 11794
• OSTI ID: 6149495
• Journal Information: Phys. Rev. D; (United States), Vol. 24:5
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
LEPTONIC DECAY
V-A THEORY
NEUTRINOS
PARTICLE PRODUCTION
ANGULAR DISTRIBUTION
EIGENSTATES
GAUGE INVARIANCE
POLARIZATION
SU-2 GROUPS
U-1 GROUPS
BASIC INTERACTIONS
DECAY
DISTRIBUTION
ELEMENTARY PARTICLES
FERMIONS
INTERACTIONS
INVARIANCE PRINCIPLES
LEPTONS
LIE GROUPS
MASSLESS PARTICLES
PARTICLE DECAY
SU GROUPS
SYMMETRY GROUPS
U GROUPS
WEAK INTERACTIONS
WEAK PARTICLE DECAY
645203* - High Energy Physics- Particle Interactions & Properties-Theoretical- Weak Interactions & Properties
645202 - High Energy Physics- Particle Interactions & Properties-Theoretical- Electromagnetic Interactions & Properties