Hierarchies in grand unification

Technical Report · Fri Jun 01 04:00:00 EDT 1984

OSTI ID:5648036

Johnson, R J

The theoretical aspiration of unifying all interactions through the mechanism of a spontaneously broken gauge symmetry received some encouragement recently with the discovery of the W/sup + -/ and Z/sup 0/ electroweak bosons predicted in the Glashow-Weinberg-Salam model of spontaneously broken SU/sub L/(2)xU/sub Y/(2). However the null results from proton decay experiments have dampened the hope that SU(5) is the correct model and placed some doubt on whether experimental evidence for grand unification can ever be seen. This situation has prompted us to look for other tests of grand unification and in particular to examine the possibility and testability of models larger than SU(5) which can have intermediate scales of symmetry breaking. We have studied some low energy models containing two light Z bosons and confronted them with the electroweak neutral current data to determine whether or not they can consistently fit it and if so what it implies for the masses of the Z bosons. The electroweak neutral currents also provide us with information on the low energy values of the gauge couplings which we used to establish limits on the hierarchy scales in an SO(10) model. Finally we discuss the theoretical fine tuning problem that arises in any model with a large scale hierarchy. The problem lies in the Higgs sector and can be related to the existence of quadratic divergences in the Higgs mass parameter. A ''naturalness'' criterion for a grand unified theory requires the absence of these quadratic divergences in order to make the hierarchy stable under radiative corrections. We show in a large class of renormalizable quantum field theories that if there occurs a cancellation of quadratic divergences for the scalar mass terms, then the only interaction structure allowed is that of supersymmetry. 63 refs.

• Research Organization: Oregon Univ., Eugene (USA). Inst. of Theoretical Science
• DOE Contract Number: AT06-76ER70004
• OSTI ID: 5648036
• Report Number(s): DOE/ER/70004-T2; ON: DE85011480
• Country of Publication: United States
• Language: English

Related Subjects

645201 -- High Energy Physics-- Particle Interactions & Properties-Theoretical-- General & Scattering Theory
645400* -- High Energy Physics-- Field Theory
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ALGEBRAIC CURRENTS
BOSONS
CURRENTS
ELEMENTARY PARTICLES
FIELD THEORIES
GRAND UNIFIED THEORY
HIGGS MODEL
INTERMEDIATE BOSONS
INTERMEDIATE VECTOR BOSONS
LIE GROUPS
MATHEMATICAL MODELS
NEUTRAL CURRENTS
PARTICLE MODELS
POSTULATED PARTICLES
QUANTUM FIELD THEORY
RENORMALIZATION
SO GROUPS
SO-10 GROUPS
STANDARD MODEL
SU GROUPS
SU-5 GROUPS
SUPERSYMMETRY
SYMMETRY
SYMMETRY BREAKING
SYMMETRY GROUPS
UNIFIED GAUGE MODELS
UNIFIED-FIELD THEORIES
WEINBERG-SALAM GAUGE MODEL