Analysis of electroweak precision data and prospects for future improvements
Kaoru Hagiwara1,2 - Dieter Haidt3 - Seiji Matsumoto1
1 Theory Group, KEK, Tsukuba, Ibaraki 305, Japan
(e-mail: kaoru.hagiwara@kek.jp)
2 ICEPP, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
(e-mail: seiji.matsumoto@kek.jp)
3 DESY, Notkestrasse 85, D-22603 Hamburg, Germany
(e-mail: haidt@dice2.desy.de)
Received: 18 June 1997
Abstract
We update our previous work on an analysis of the electroweak data
by including new and partly preliminary data available up to the 1996
summer conferences.
The new results on the Z partial decay widths into b and c
hadrons now offer a consistent interpretation of all data in the
minimal standard model.
The value extracted for the strong interaction coupling constant
agrees well with determinations in other areas.
New constraints on the universal parameters S, T and U are obtained
from the updated measurements.
No signal of new physics is found in the S, T, U analysis once
the SM contributions with
GeV and those of not a too heavy
Higgs boson are accounted for.
The naive QCD-like technicolor model is now ruled out at the 99% CL
even for the minimal model with
.In the absence of a significant new physics effect in the electroweak
observables, constraints on masses of the top quark, mt,
and Higgs boson, mH, are
derived as a function
of
and the QED effective coupling
.The preferred range of mH depends rather strongly on the actual value
of mt:
for
, while
for
at 95% CL.
Prospects due to forthcoming improved measurements of asymmetries,
the mass of the weak boson W
mW, mt and
are discussed.
Anticipating uncertainties of
0.00020 for
, 20 MeV for mW,
and 2 GeV for mt, the new physics contributions to the S, T, U
parameters will be constrained more severely,
and, within the SM,
the logarithm of the Higgs mass can be constrained to about
.The better constraints on S, T, U and on mH within the minimal SM
should be accompanied with matching precision in
.
Copyright Springer-Verlag