Tau anomaly and vectorlike families

Journal Article · Tue Sep 01 00:00:00 EDT 1992 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.46.2190· OSTI ID:7261726

Babu, K S ^[1]; Pati, J C; Zhang, X ^[2]

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1. Bartol Research Institute, University of Delaware, Newark, Delaware 19716 (United States)
2. Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

The implications of a recently indicated increase in {tau} lifetime are discussed. It is stressed that the available experimental constraints (from {delta}{rho},{epsilon}{sub 3}, and {ital N}{sub {nu}}, etc.) are satisfied most naturally if the indicated {tau} anomaly is attributed to the mixing of the {tau} family with a heavy vectorlike family {ital Q}{sub {ital L},}{ital R}{sup {prime}} with masses {similar to}200 GeV to 2 TeV, which is a doublet of SU(2){sub {ital R}} and singlet of SU(2){sub {ital L}}, rather than with a heavy fourth family with standard chiral couplings. {ital L}{leftrightarrow}{ital R} symmetry would imply that {ital Q}{sub {ital L},}{ital R}{sup {prime}} is accompanied by the parity-conjugate family {ital Q}{sub {ital L},}{ital R} which is a doublet of SU(2){sub {ital L}} and singlet of SU(2){sub {ital R}}. Two such vectorlike families, together with an increase in {tau}{sub {tau}}, are, in fact, crucial predictions of a recently proposed supersymmetric composite model that possesses many attractive features, in particular, explanations of the origin of diverse scales and family replication. In the context of such a model, it is noted that 3 an increase in {tau}{sub {tau}} due to mixing involving vectorlike families will necessarily imply a correlated decrease in neutrino counting {ital N}{sub {nu}} from the CERN {ital e}{sup +}{ital e{minus}} {ital collider} LEP {ital from} 3. Such a decrease in {ital N}{sub {nu}} would be absent, however, if the {tau} anomaly is attributed to a mixing involving a standard fourth family with chiral couplings. Because of the seesaw nature of the mass matrix of the three chiral and two vectorlike families, that arises naturally in the model, departures from universality in the first two families as well as in {ital {bar b}b} and {tau}{sup +}{tau}{sup {minus}} channels (linked to down flavors) are strongly suppressed, in accord with observations.

• OSTI ID: 7261726
• Journal Information: Physical Review, D (Particles Fields); (United States), Vol. 46:5; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
TAU PARTICLES
LIFETIME
BRANCHING RATIO
CHIRAL SYMMETRY
COMPOSITE MODELS
COUPLING
LEP STORAGE RINGS
MASS
NEUTRINOS
PARITY
PARTICLE DECAY
SU-2 GROUPS
SU-3 GROUPS
SUPERSYMMETRY
U-1 GROUPS
VECTORS
DECAY
ELEMENTARY PARTICLES
FERMIONS
HEAVY LEPTONS
LEPTONS
LIE GROUPS
MASSLESS PARTICLES
MATHEMATICAL MODELS
PARTICLE MODELS
PARTICLE PROPERTIES
POSTULATED PARTICLES
STORAGE RINGS
SU GROUPS
SYMMETRY
SYMMETRY GROUPS
TENSORS
U GROUPS
662370* - Decays of Leptons- (1992-)
662120 - General Theory of Particles & Fields- Symmetry
Conservation Laws
Currents & Their Properties- (1992-)