1,950 research outputs found
Electroweak Radiative Corrections To Polarized M{\o}ller Scattering Asymmetries
One loop electroweak radiative corrections to left-right parity violating
M{\o}ller scattering () asymmetries are presented. They
reduce the standard model (tree level) prediction by 40 \% where the
main shift and uncertainty stem from hadronic vacuum polarization loops. A
similar reduction also occurs for the electron-electron atomic parity violating
interaction. That effect can be attributed to an increase of
by in running from to 0. The
sensitivity of the asymmetry to ``new physics'' is also discussed.Comment: 14 pages, Revtex, postscript file including figures is available at
ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-14/ttp95-14.ps or via WWW at
http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints/ (129.13.102.139
SM Kaluza-Klein Excitations and Electroweak Precision Tests
We consider a minimal extension to higher dimensions of the Standard Model,
having one compactified dimension, and we study its experimental tests in terms
of electroweak data. We discuss tests from high-energy data at the -pole,
and low-energy tests, notably from atomic parity violation data. This
measurement combined with neutrino scattering data strongly restricts the
allowed region of the model parameters. Furthermore this region is incompatible
at 95% CL with the restrictions from high-energy experiments. Of course a
global fit to all data is possible but the for degree of
freedom is unpleasantly large.Comment: LaTex, 14 pages, 2 figures. More refs. and one comment about the
validity of our results for any number of extra dimensions adde
K_L \ra \mu^\pm e^\mp \nu \overline{\nu} as background to K_L \ra \mu^\pm e^\mp
We consider the process K_L \ra \mu^\pm e^\mp \nu \overline{\nu} at next to
leading order in chiral perturbation theory. This process occurs in the
standard model at second order in the weak interaction and constitutes a
potential background in searches for new physics through the modes K_L \ra
\mu^\pm e^\mp. We find that the same cut, ~MeV, used to remove
the sequential decays K_{l3}\ra \pi_{l2} pushes the B(K_L \ra \mu^\pm e^\mp
\nu \overline{\nu}) to the level, effectively removing it as a
background.Comment: 8 pages, LaTeX, 1 figure appended as postscript file after
\end{document}. Fermilab-Pub-93/024-
Confining Configurations in QCD and Relation to Rigid Strings
The gauge field configurations of QCD gauge fields in the infrared regime are
obtained by magnetic symmetry condition. The effective dual action exhibits
dual Meissner effect with quarks included. A string representation of this
action corresponds to rigid string.Comment: 3 pages, Latex file, usepackage fleqn, espcrc2. Talk given in the
parallel session of the XVIII International Sympposium on Lattice Field
Theory, August 2000, held at Bangalore, Indi
Precision Probes of a Leptophobic Z' Boson
Extensions of the Standard Model that contain leptophobic Z' gauge bosons are
theoretically interesting but difficult to probe directly in high-energy hadron
colliders. However, precision measurements of Standard Model neutral current
processes can provide powerful indirect tests. We demonstrate that
parity-violating deep inelastic scattering of polarized electrons off of
deuterium offer a unique probe leptophobic Z' bosons with axial quark couplings
and masses above 100 GeV. In addition to covering a wide range of previously
uncharted parameter space, planned measurements of the deep inelastic
parity-violating eD asymmetry would be capable of testing leptophobic Z'
scenarios proposed to explain the CDF W plus di-jet anomaly.Comment: 5 page, 1 figur
Evidence for Bosonic Electroweak Corrections in the Standard Model
We present strong indirect evidence for the contribution of bosonic
electroweak corrections in the Standard Model. Although important conceptually,
these corrections give subleading contributions in current high energy
experiments, and it was previously thought that they are difficult to detect.
We also discuss the separate contribution of the Higgs boson.Comment: 9 pages (LaTeX + 3 PS figures, needs psfig
Fermi Constants and ``New Physics''
Various precision determinations of the Fermi constant are compared. Included
are muon and (leptonic) tau decays as well as indirect prescriptions employing
\alpha, m_Z, m_W, \ssthwmzms, \Gamma(Z\to\ell^+\ell^-), and as input. Their good agreement tests the standard model at the
level and provides stringent constraints on new physics. That
utility is illustrated for: heavy neutrino mixing, 2 Higgs doublet models, S,
T, and U parameters and excited bosons (Kaluza-Klein
excitations). For the last of those examples, m_{W^\ast}\gsims 2.9 TeV is
found.Comment: 14 page
New analytic running coupling in spacelike and timelike regions
The new model for the QCD analytic running coupling, proposed recently, is
extended to the timelike region. This running coupling naturally arises under
unification of the analytic approach to QCD and the renormalization group (RG)
formalism. A new method for determining the coefficients of the "analytized" RG
equation is elaborated. It enables one to take into account the higher loop
contributions to the new analytic running coupling (NARC) in a consistent way.
The expression for the new analytic running coupling, independent of the
normalization point, is obtained by invoking the asymptotic freedom condition.
It is shown that the difference between the values of the NARC in respective
spacelike and timelike regions is rather valuable for intermediate energies.
This is essential for the correct extracting of the running coupling from
experimental data. The new analytic running coupling is applied to the
description of the inclusive lepton decay. The consistent estimation of
the parameter is obtained here.Comment: REVTeX 3.1, 12 pages with 3 EPS figures; enlarged version is
published in Phys. Rev.
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