Journal Article

PUBDB-2017-03426

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Comprehensive analysis of data pertaining to the weak neutral current and the intermediate-vector-boson masses

Amaldi, U. ; Böhm, A. ; Durkin, L. S. ; Langacker, P. ; Mann, A. K. ; Marciano, W. J. ; Sirlin, A. (Corresponding author) ; Williams, H. H.

1987
Inst. Woodbury, NY

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Please use a persistent id in citations: doi:10.1103/PhysRevD.36.1385  doi:10.3204/PUBDB-2017-03426

Abstract: The results of a comprehensive analysis of existing data on the weak neutral current and the W and Z masses are presented. The principal results are the following. (a) There is no evidence for any deviation from the standard model. (b) A global fit to all data yields sin$^2$θ$_W$≡1-M$_W$$^2$/M$_Z$$^2$=0.230±0.0048, where this error and all others given here include full statistical, systematic, and theoretical uncertainties (computed assuming three fermion families, m$_t$≤100 GeV, and M$_H$≤1 TeV). (c) Allowing ρ≡M$_W$$^2$/(M$_Z$$^2$cos$^2$θ$_W$) as well as sin$^2$θ$_W$ to vary one obtains sin$^2$θ$_W$=0.229±0.0064 and ρ=0.998±0.0086. This implies 90%-confidence-level (C.L.) upper limits of 0.047 and 0.081 for the vacuum expectation values (relative to those of Higgs doublets) for Higgs triplets with weak hypercharge of 0 and ±1, respectively. (d) The parameter δ$_W$≡Δr-Δs$^2$(1-Δr)/sin$^2$θ$_0$, which is a measure of the radiative corrections relating deep-inelastic neutrino scattering, the W and Z masses, and muon decay, is determined to be 0.112±0.037. This is consistent with the value δ$_W$=0.106 expected for m$_t$=45 GeV and M$_H$=100 GeV and establishes the existence of radiative corrections at the 3σ level. (e) The radiative corrections are sensitive to isospin breaking associated with a large mt.Assuming no deviation from the standard model, consistency of the various reactions requires mt<180 GeV at 90% C.L. for MH≤100 GeV, with a slightly weaker limit for larger MH. Similar results hold for the mass splittings between fourth-generation quarks or leptons. (f) Most of the parameters in model-independent fits to ν$_q$, ν$_e$, e$_q$, and e$^+$e$^−$ processes are now determined uniquely and precisely. (g) Limits are given on the masses and mixing angles of additional Z bosons expected in popular models. For theoretically expected coupling constants one finds that the neutral-current constraints are usually more stringent than the direct-production limits from the CERN Sp¯pS collider, but nevertheless masses as low as 120–300 GeV are typically allowed. (h) The implications of these results for grand unification are discussed. sin$^2$θ$_W$ is ≥2.5 standard deviations above the prediction of minimal SU(5) and similar models for all mt. It is closer to the prediction of simple supersymmetric grand unified theories but is still somewhat low. (i) The dominant theoretical uncertainty (the charm-quark threshold in deep-inelastic charged-current scattering) is considered in some detail.

Note: MARK J

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Contributing Institute(s):

1. DESY Retrocat (DESY(-2012))

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Experiment(s):

1. No specific instrument

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Database coverage:
; ; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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