10,723 research outputs found
Physics Beyond the Standard Model
In these three lectures I review the need to go beyond the Standard Glashow-
Weinberg-Salam Model and discuss some of the approaches that are explored in
this direction.Comment: 5 pages, contribution to the CERN-Latin-American School of
High-Energy Physics, Ibarra, Ecuador, 4 - 17 March 2015
Reconstruction of interacting dark energy models from parameterizations
Models with interacting dark energy can alleviate the cosmic coincidence
problem by allowing dark matter and dark energy to evolve in a similar fashion.
At a fundamental level, these models are specified by choosing a functional
form for the scalar potential and for the interaction term. However, in order
to compare to observational data it is usually more convenient to use
parameterizations of the dark energy equation of state and the evolution of the
dark matter energy density. Once the relevant parameters are fitted it is
important to obtain the shape of the fundamental functions. In this paper I
show how to reconstruct the scalar potential and the scalar interaction with
dark matter from general parameterizations. I give a few examples and show that
it is possible for the effective equation of state for the scalar field to
cross the phantom barrier when interactions are allowed. I analyze the
uncertainties in the reconstructed potential arising from foreseen errors in
the estimation of fit parameters and point out that a Yukawa-like linear
interaction results from a simple parameterization of the coupling.Comment: 6 pages, 8 figure
Technicolor contribution to lepton + photon + missing energy events at the Tevatron
Events with one lepton, one photon and missing energy are the subject of
recent searches at the Fermilab Tevatron. We compute possible contributions to
these type of events from the process p pbar --> photon l nu_l nu_tau
nubar_tau, where l=e,mu in the context of a Low Scale Technicolor Model. We
find that with somewhat tighter cuts than the ones used in the CDF search, it
could be possible to either confirm or exclude this model in a small region of
its parameter space.Comment: 4 pages, 3 figures. Improved text and figures, including comments and
new reference
Limits on a Strong Electroweak Sector from e^+ e^- -> 2gamma + missing E at LEP2
We study the process in the context
of a strong electroweak symmetry breaking model, which can be a source of
events with two photons and missing energy at LEP2. We investigate bounds on
the model assuming that no deviation is observed from the Standard Model within
a given experimental error.Comment: 7 pages, Latex, one figur
Orbital order, stacking defects and spin-fluctuations in the -electron molecular solid RbO
We examine magnon and orbiton behavior in localized O anti-bonding
molecular orbitals using an effective Kugel-Khomskii Hamiltonian
derived from a two band Hubbard model with hopping parameters taken from {\em
ab initio} density functional calculations. The considerable difference between
intraband and interband hoppings leads to a strong coupling between the spin
wave dispersion and the orbital ground state, providing a straightforward way
of experimentally determining the orbital ground state from the measured magnon
dispersion. The near degeneracy of different orbital ordered states leads to
stacking defects which further modulate spin-fluctuation spectra. Proliferation
of orbital domains disrupts long-range magnetic order, thus causing a
significant reduction in the observed N\'eel temperature.Comment: 5 pages, 2 figure
Recommended from our members
STRONGLY COUPLED ELECTROWEAK SYMMETRY BREAKING: IMPLICATIONS OF MODELS
We discuss the phenomenology of models of dynamical electroweak symmetry
breaking which attempt to generate the observed fermion mass spectrum. After
briefly describing the variety of and constraints on proposed models, we
concentrate on the signatures of colored pseudo-Nambu-Goldstone bosons and
resonances at existing and proposed colliders. These particles provide a
possibly unique signature: strongly produced resonances associated with
electroweak symmetry breaking. (This is the subgroup report for the
``Electroweak Symmetry Breaking and Beyond the Standard Model" working group of
the DPF Long Range Planning Study. This report will appear as a chapter in
``Electroweak Symmetry Breaking and Beyond the Standard Model", edited by T.
Barklow, S. Dawson, H.E. Haber, and J. Siegrist, to be published by World
Scientific.
The Higgs portal and an unified model for dark energy and dark matter
We examine a scenario where the Higgs boson is coupled to an additional
singlet scalar field which we identify with a quintessence field. We show that
this results in an unified picture of dark matter and dark energy, where dark
energy is the zero-mode classical field rolling the usual quintessence
potential and the dark matter candidate is the quantum excitation (particle) of
the field, which is produced in the universe due to its coupling to the Higgs
boson.Comment: 5 pages, no figures. New references and acknowledgment adde
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