TY - JOUR
T1 - Constraints on additional Z bosons
AU - Langacker, Paul
AU - Luo, Mingxing
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 1992
Y1 - 1992
N2 - Z-pole, W-mass, and weak neutral-current (WNC) data as well as direct collider limits are used to constrain the mass and mixing of possible heavy Z2 bosons with couplings expected in grand unified theories and SU(2)L×SU(2)R×U(1) models. The data now enable the top-quark mass and Z2 properties to be limited simultaneously. The indirect (Z-pole, MW, WNC) data stringently constrain the Z10-Z20 mixing angle (||<0.01 in most cases). For models with arbitrary Higgs representations, the limits on the Z2 mass M2 from indirect and direct constraints are rather weak (typically 160-400 GeV), but in specific models in which M2 and are correlated, the constraints are much stronger (M2>500-1000 GeV). The weak angle in the modified minimal subtraction scheme is well determined even allowing for extra Z's and an arbitrary Higgs structure: sin2W(MZ)=0.2334-0.0011+0.0008, for the models considered, where the uncertainties include mt, compared to the SU(2)×U(1) model value 0.23330.0008. The 95%-C.L. upper limits on mt (mt<182 GeV for Higgs doublets and singlets only, and mt<310 GeV for arbitrary Higgs representations) continue to hold in the presence of the extra Z's considered. The implications of these results for ordinary and supersymmetric grand unification, atomic parity violation, charged-current universality, R (e+e-+-, hadrons) below the Z pole, and superstring theories are discussed. A nongauge model in which the Z2 has the same couplings as the ordinary Z is included for comparison.
AB - Z-pole, W-mass, and weak neutral-current (WNC) data as well as direct collider limits are used to constrain the mass and mixing of possible heavy Z2 bosons with couplings expected in grand unified theories and SU(2)L×SU(2)R×U(1) models. The data now enable the top-quark mass and Z2 properties to be limited simultaneously. The indirect (Z-pole, MW, WNC) data stringently constrain the Z10-Z20 mixing angle (||<0.01 in most cases). For models with arbitrary Higgs representations, the limits on the Z2 mass M2 from indirect and direct constraints are rather weak (typically 160-400 GeV), but in specific models in which M2 and are correlated, the constraints are much stronger (M2>500-1000 GeV). The weak angle in the modified minimal subtraction scheme is well determined even allowing for extra Z's and an arbitrary Higgs structure: sin2W(MZ)=0.2334-0.0011+0.0008, for the models considered, where the uncertainties include mt, compared to the SU(2)×U(1) model value 0.23330.0008. The 95%-C.L. upper limits on mt (mt<182 GeV for Higgs doublets and singlets only, and mt<310 GeV for arbitrary Higgs representations) continue to hold in the presence of the extra Z's considered. The implications of these results for ordinary and supersymmetric grand unification, atomic parity violation, charged-current universality, R (e+e-+-, hadrons) below the Z pole, and superstring theories are discussed. A nongauge model in which the Z2 has the same couplings as the ordinary Z is included for comparison.
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U2 - 10.1103/PhysRevD.45.278
DO - 10.1103/PhysRevD.45.278
M3 - Article
AN - SCOPUS:0000077529
VL - 45
SP - 278
EP - 292
JO - Physical review D: Particles and fields
JF - Physical review D: Particles and fields
SN - 1550-7998
IS - 1
ER -