827 research outputs found
Neutrinos in 5D SO(10) Unification
We study neutrino physics in a 5D supersymmetric SO(10) GUT. We analyze
several different choices for realizing the See-Saw mechanism. We find that the
"natural" scale for the Majorana mass of right-handed neutrinos depends
critically on whether the right-handed neutrinos are located in the bulk or
localized on a brane. In the former case, the effective Majorana mass is
"naturally" of order the compactification scale, about 10^{14} GeV. Note, this
is the value necessary for obtaining a light tau neutrino mass approximately
10^{-2} eV which, within the context of hierarchical neutrino masses, is the
right order of magnitude to explain atmospheric neutrino oscillations. On the
other-hand when the right-handed neutrino is localized on the brane, the
effective Majorana mass is typically larger than the compactification scale.
Nevertheless with small parameters of order 1/10 - 1/30, an effective Majorana
mass of order 10^{14} GeV can be accommodated. We also discuss the constraints
on model building resulting from the different scenarios for locating the
right-handed neutrinos.Comment: 24 page
Carbon monoxide-releasing antibacterial molecules target respiration and global transcriptional regulators
Carbon monoxide, a classical respiratory inhibitor, also exerts vasodilatory, anti-inflammatory, and antiapoptotic effects. CO-releasing molecules have therapeutic value, increasing phagocytosis and reducing sepsis-induced lethality. Here we identify for the first time the bacterial targets of Ru(CO)(3)Cl(glycinate) (CORM-3), a ruthenium-based carbonyl that liberates CO rapidly under physiological conditions. Contrary to the expectation that CO would be preferentially inhibitory at low oxygen tensions or anaerobically, Escherichia coli cultures were also sensitive to CORM-3 at concentrations equimolar with oxygen. CORM-3, assayed as ruthenium, was taken up by bacteria and rapidly delivered CO intracellularly to terminal oxidases. Microarray analysis of CORM-3-treated cells revealed extensively modified gene expression, notably down-regulation of genes encoding key aerobic respiratory complexes. Genes involved in metal metabolism, homeostasis, or transport were also differentially expressed, and free intracellular zinc levels were elevated. Probabilistic modeling of transcriptomic data identified the global transcription regulators ArcA, CRP, Fis, FNR, Fur, BaeR, CpxR, and IHF as targets and potential CO sensors. Our discovery that CORM-3 is an effective inhibitor and global regulator of gene expression, especially under aerobic conditions, has important implications for administration of CO-releasing agents in sepsis and inflammatio
Doubly charged Higgs from - scattering in the 3-3-1 Model
We studied the production and signatures of doubly charged Higgs bosons in
the process , where is a heavy lepton,
at the International Linear Collider (ILC) and CERN Linear Collider
(CLIC). The intermediate photons are given by the Weizscker-Williams
and laser backscattering distributions. We found that significant signatures
are obtained by bremsstrahlung and backward Comptom scattering of laser. A
clear signal can be obtained for doubly charged Higgs bosons, doubly charged
gauge bosons and heavy leptons
A quasilocal calculation of tidal heating
We present a method for computing the flux of energy through a closed surface
containing a gravitating system. This method, which is based on the quasilocal
formalism of Brown and York, is illustrated by two applications: a calculation
of (i) the energy flux, via gravitational waves, through a surface near
infinity and (ii) the tidal heating in the local asymptotic frame of a body
interacting with an external tidal field. The second application represents the
first use of the quasilocal formalism to study a non-stationary spacetime and
shows how such methods can be used to study tidal effects in isolated
gravitating systems.Comment: REVTex, 4 pages, 1 typo fixed, standard sign convention adopted for
the Newtonian potential, a couple of lines added to the discussion of gauge
dependent term
Seesaw Extended MSSM and Anomaly Mediation without Tachyonic Sleptons
Superconformal anomalies provide an elegant and economical way to understand
the soft breaking parameters in SUSY models; however, implementing them leads
to the several undesirable features including: tachyonic sleptons and
electroweak symmetry breaking problems in both the MSSM and the NMSSM. Since
these two theories also have the additonal problem of massless neutrinos, we
have reconsidered the AMSB problems in a class of models that extends the NMSSM
to explain small neutrino masses via the seesaw mechanism. In a recent paper,
we showed that for a class of minimal left-right extensions, a built-in
mechanism exists which naturally solves the tachyonic slepton problem and
provides new alternatives to the MSSM that also have automatic R-parity
conservation. In this paper, we discuss how electroweak symmetry breaking
arises in this model through an NMSSM-like low energy theory with a singlet
VEV, induced by the structure of the left-right extension and of the right
magnitude. We then study the phenomenological issues and find: the LSP is an
Higgsino-wino mix, new phenomenology for chargino decays to the LSP, degenerate
same generation sleptons and a potential for a mild squark-slepton degeneracy.
We also discuss possible collider signatures and the feasibility of dark matter
in this model.Comment: 40 pages, 10 figures, 5 tables; v3: Added addendum and three new
references; v4: Added reference that was inadvertently omitte
Coronal Shock Waves, EUV waves, and their Relation to CMEs. II. Modeling MHD Shock Wave Propagation Along the Solar Surface, Using Nonlinear Geometrical Acoustics
We model the propagation of a coronal shock wave, using nonlinear geometrical
acoustics. The method is based on the Wentzel-Kramers-Brillouin (WKB) approach
and takes into account the main properties of nonlinear waves: i) dependence of
the wave front velocity on the wave amplitude, ii) nonlinear dissipation of the
wave energy, and iii) progressive increase in the duration of solitary shock
waves. We address the method in detail and present results of the modeling of
the propagation of shock-associated extreme-ultraviolet (EUV) waves as well as
Moreton waves along the solar surface in the simplest solar corona model. The
calculations reveal deceleration and lengthening of the waves. In contrast,
waves considered in the linear approximation keep their length unchanged and
slightly accelerate.Comment: 15 pages, 7 figures, accepted for publication in Solar Physic
(B-L) Symmetry vs. Neutrino Seesaw
We compute the effective coupling of the Majoron to W bosons at \cO(\hbar)
by evaluating the matrix element of the (B-L) current between the vacuum and a
state. The (B-L) anomaly vanishes, but the amplitude does not vanish
as a result of a UV finite and non-local contribution which is entirely due to
the mixing between left-chiral and right-chiral neutrinos. The result shows how
anomaly-like couplings may arise in spite of the fact that the (B-L) current
remains exactly conserved to all orders in , lending additional support
to our previous proposal to identify the Majoron with the axion.Comment: 13 pages, 1 figure, with additional explanations and clarification
Electromagnetic Polarization Effects due to Axion Photon Mixing
We investigate the effect of axions on the polarization of electromagnetic
waves as they propagate through astronomical distances. We analyze the change
in the dispersion of the electromagnetic wave due to its mixing with axions. We
find that this leads to a shift in polarization and turns out to be the
dominant effect for a wide range of frequencies. We analyze whether this effect
or the decay of photons into axions can explain the large scale anisotropies
which have been observed in the polarizations of quasars and radio galaxies. We
also comment on the possibility that the axion-photon mixing can explain the
dimming of distant supernovae.Comment: 18 pages, 1 figur
The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos
We implement the seesaw mechanism in the 3-3-1 model with right-handed
neutrinos. This is accomplished by the introduction of a scalar sextet into the
model and the spontaneous violation of the lepton number. We identify the
Majoron as a singlet under symmetry, which makes it
safe under the current bounds imposed by electroweak data. The main result of
this work is that the seesaw mechanism works already at TeV scale with the
outcome that the right-handed neutrino masses lie in the electroweak scale, in
the range from MeV to tens of GeV. This window provides a great opportunity to
test their appearance at current detectors, though when we contrast our results
with some previous analysis concerning detection sensitivity at LHC, we
conclude that further work is needed in order to validate this search.Comment: about 13 pages, no figure
Rotating Resonator-Oscillator Experiments to Test Lorentz Invariance in Electrodynamics
In this work we outline the two most commonly used test theories (RMS and
SME) for testing Local Lorentz Invariance (LLI) of the photon. Then we develop
the general framework of applying these test theories to resonator experiments
with an emphasis on rotating experiments in the laboratory. We compare the
inherent sensitivity factors of common experiments and propose some new
configurations. Finally we apply the test theories to the rotating cryogenic
experiment at the University of Western Australia, which recently set new
limits in both the RMS and SME frameworks [hep-ph/0506074].Comment: Submitted to Lecture Notes in Physics, 36 pages, minor modifications,
updated list of reference
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