New precision electroweak tests of SU(5)[times]U(1) supergravity

Journal Article · Sun May 01 04:00:00 EDT 1994 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.49.4835· OSTI ID:5016795

Lopez, J L; Nanopoulos, D V; Park, G T; Zichichi, A ^[1]

---

1. Center for Theoretical Physics, Department of Physics, Texas A M University, College Station, Texas 77843-4242 (United States) Astroparticle Physics Group, Houston Advanced Research Center (HARC), The Mitchell Campus, The Woodlands, Texas 77381 (United States) CERN, Theory Division, 1211 Geneva 23 (Switzerland) CERN, 1211 Geneva 23 (Switzerland)

We explore the one-loop electroweak radiative corrections in SU(5)[times]U(1) supergravity via explicit calculation of vacuum-polarization and vertex-correction contributions to the [epsilon][sub 1] and [epsilon][sub [ital b]] parameters. Experimentally, these parameters are obtained from a global fit to the set of observables [Gamma][sub [ital l]], [Gamma][sub [ital b]], [ital A][sub FB][sup [ital l]], and [ital M][sub [ital W]]/[ital M][sub [ital Z]]. We include [ital q][sup 2]-dependent effects, which induce a large systematic negative shift on [epsilon][sub 1] for light chargino masses ([ital m][sub [chi]1][sup [plus minus]][approx lt]70 GeV). The (nonoblique) supersymmetric vertex corrections to [ital Z][r arrow][ital b[bar b]], which define the [epsilon][sub [ital b]] parameter, show a significant positive shift for light chargino masses, which for tan[beta][approx]2 can be nearly compensated by a negative shift from the charged Higgs contribution. We conclude that, at the 90% C.L., for [ital m][sub [ital t]][approx lt]160 GeV the present experimental values of [epsilon][sub 1] and [epsilon][sub [ital b]] do not constrain in any way SU(5)[times]U(1) supergravity in both no-scale and dilaton scenarios. On the other hand, for [ital m][sub [ital t]][approx gt]160 GeV the constraints on the parameter space become increasingly more strict. We demonstrate this trend with a study of the [ital m][sub [ital t]]=170 GeV case, where only a small region of parameter space, with tan[beta][approx gt]4, remains allowed and corresponds to light chargino masses ([ital m][sub [chi]1][sup [plus minus]][approx lt]70 GeV). Thus SU(5)[times]U(1) supergravity combined with high-precision CERN LEP data would suggest the presence of light charginos if the top quark is not detected at the Fermilab Tevatron.

• DOE Contract Number: FG05-91ER40633
• OSTI ID: 5016795
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 49:9; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

661310 -- Relativity & Gravitation-- (1992-)
662210* -- Specific Theories & Interaction Models
662440 -- Properties of Other Particles Including Hypothetical Particles-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CORRECTIONS
FIELD THEORIES
FUNCTIONS
LIE GROUPS
Pa
Particle Systematics-- Unified Theories & Models-- (1992-)
RADIATIVE CORRECTIONS
SU GROUPS
SU-5 GROUPS
SUPERGRAVITY
SUPERSYMMETRY
SYMMETRY
SYMMETRY GROUPS
TESTING
U GROUPS
U-1 GROUPS
UNIFIED-FIELD THEORIES
VACUUM POLARIZATION
VERTEX FUNCTIONS