1,833 research outputs found
Low Energy Tests of the Weak Interaction
The study of low energy weak interactions of light quarks and leptons
continues to provide important insights into both the Standard Model as well as
the physics that may lie beyond it. We review the status and future prospects
for low energy electroweak physics. Recent important experimental and
theoretical developments are discussed and open theoretical issues are
highlighted. Particular attention is paid to neutrino physics, searches for
permanent electric dipole moments, neutral current tests of the running of the
weak mixing angle, weak decays, and muon physics. We argue that the broad range
of such studies provides an important complement to high energy collider
searches for physics beyond the Standard Model. The use of low energy weak
interactions to probe novel aspects of hadron structure is also discussed.Comment: 82 pages, 6 figures: published version (with some additional
references and a typographical error fixed
The Probability Density of the Higgs Boson Mass
The LEP Collaborations have reported a small excess of events in their
combined Higgs boson analysis at center of mass energies up to about 208 GeV.
In this communication, I present the result of a calculation of the probability
distribution function of the Higgs boson mass which can be rigorously obtained
if the validity of the Standard Model is assumed. It arises from the
combination of the most recent set of precision electroweak data and the
current results of the Higgs searches at LEP 2.Comment: 3 pages, 2 figure
Z' Searches: From Tevatron to LHC
The CDF collaboration has set lower limits on the masses of the Z' bosons
occurring in a range of E_6 GUT based models. We revisit their analysis and
extend it to certain other E_6 scenarios as well as to some general classes of
models satisfying the anomaly cancellation conditions, which are not included
in the CDF analysis. We also suggest a Bayesian statistical method for finding
exclusion limits on the Z' mass, which allows one to explore a wide range of
the U(1)' gauge coupling parameter. This method also takes into account the
effects of interference between the Z' and the SM gauge bosons.Comment: 5 pages. Talk given at the XXIInd Rencontres de Blois, Loire, France,
16-20 July 201
Constraints on the mass and mixing of Z' bosons
We tested several models in which the Standard Model (SM) gauge group is
extended by an additional U(1) gauge symmetry, against available electroweak
precision data to impose limits on the mass of the neutral Z' boson, M_Z',
predicted in all such models, and on the Z-Z' mixing angle, theta_ZZ', at 95%
C.L. We found lower limits on M_Z' of order 1 TeV in most cases, while
theta_ZZ' was found to be constrained to very small values.Comment: Format fixed, 5 pages, 2 figures, Talk given at the 17th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions (SUSY09), Boston, MA, USA, 5-10 June 2009, to be published in
the conference proceedings (AIP
Electroweak Constraints from Atomic Parity Violation and Neutrino Scattering
Precision electroweak physics can provide fertile ground for uncovering new
physics beyond the Standard Model (SM). One area in which new physics can
appear is in so-called "oblique corrections", i.e., next-to-leading order
expansions of bosonic propagators corresponding to vacuum polarization. One may
parametrize their effects in terms of quantities and that discriminate
between conservation and non-conservation of isospin. This provides a means of
comparing the relative contributions of precision electroweak experiments to
constraints on new physics. Given the prevalence of strongly -sensitive
experiments, there is an acute need for further constraints on , such as
provided by atomic parity-violating experiments on heavy atoms. We evaluate
constraints on arising from recently improved calculations in the Cs atom.
We show that the top quark mass provides stringent constraints on
within the context of the Standard Model. We also consider the potential
contributions of next-generation neutrino scattering experiments to improved
constraints.Comment: 10 pages, 4 figures, final corrected version to be published in
Physical Review
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