695 research outputs found
Magnetic field generation in Higgs inflation model
We study the generation of magnetic field in Higgs-inflation models where the
Standard Model Higgs boson has a large coupling to the Ricci scalar. We couple
the Higgs field to the Electromagnetic fields via a non- renormalizable
dimension six operator suppressed by the Planck scale in the Jordan frame. We
show that during Higgs inflation magnetic fields with present value
Gauss and comoving coherence length of can be generated in the
Einstein frame. The problem of large back-reaction which is generic in the
usual inflation models of magneto-genesis is avoided as the back-reaction is
suppressed by the large Higgs-curvature coupling.Comment: 10 pages, RevTeX
On the Naturalness of Higgs Inflation
We critically examine the recent claim that the Standard Model Higgs boson
could drive inflation in agreement with observations if has a strong coupling to the Ricci curvature scalar. We
first show that the effective theory approach upon which that claim is based
ceases to be valid beyond a cutoff scale , where is the
reduced Planck mass. We then argue that knowing the Higgs potential profile for
the field values relevant for inflation () requires knowledge of the ultraviolet completion of the SM beyond
. In absence of such microscopic theory, the extrapolation of the pure
SM potential beyond is unwarranted and the scenario is akin to other
ad-hoc inflaton potentials afflicted with significant fine-tuning. The
appealing naturalness of this minimal proposal is therefore lost.Comment: 9 pages. Replaced with published version, plus a footnote clarifying
the use of power counting estimate
Circumventing the eta problem in building an inflationary model in string theory
The eta problem is one of the most significant obstacles to building a
successful inflationary model in string theory. Planck mass suppressed
corrections to the inflaton potential generally lead to inflaton masses of
order the Hubble scale and generate contributions of order unity to the eta
slow roll parameter rendering prolonged slow roll inflation impossible. We
demonstrate the severity of this problem in the context of brane anti-brane
inflation in a warped throat of a Calabi-Yau flux compactification with all
phenomenologically dangerous moduli stabilized. Using exact numerical solutions
we show that the eta problem can be avoided in scenarios where the inflaton is
non-minimally coupled to gravity and has Dirac-Born-Infeld (DBI) kinetic term.
We show that the resulting cosmic microwave background (CMB) observables such
as measures of non-gaussianites can, in principle, serve as a probe of
scalar-gravity couplings.Comment: 8 pages, 3 figures; title changed and reference added to match
published version in PR
Tau energy losses at ultra-high energy: continuous versus stochastic treatment
We study the energy losses of the tau lepton in matter through
electromagnetic processes at ultra-high energy (UHE). We use both a stochastic
and a continuous framework to treat these interactions and compare the flux of
tau leptons propagated after some amount of matter. We discuss the accuracy of
the approximation of continuous energy losses by studying the propagation in
standard rock of taus with both mono-energetic and power law injection spectra.Comment: 7 pages, 8 figure
Stochastic Resonance in Ion Channels Characterized by Information Theory
We identify a unifying measure for stochastic resonance (SR) in voltage
dependent ion channels which comprises periodic (conventional), aperiodic and
nonstationary SR. Within a simplest setting, the gating dynamics is governed by
two-state conductance fluctuations, which switch at random time points between
two values. The corresponding continuous time point process is analyzed by
virtue of information theory. In pursuing this goal we evaluate for our
dynamics the tau-information, the mutual information and the rate of
information gain. As a main result we find an analytical formula for the rate
of information gain that solely involves the probability of the two channel
states and their noise averaged rates. For small voltage signals it simplifies
to a handy expression. Our findings are applied to study SR in a potassium
channel. We find that SR occurs only when the closed state is predominantly
dwelled. Upon increasing the probability for the open channel state the
application of an extra dose of noise monotonically deteriorates the rate of
information gain, i.e., no SR behavior occurs.Comment: 10 pages, 2 figures, to appear in Phys. Rev.
Relativistic Magnetic Monopole Flux Constraints from RICE
We report an upper limit on the flux of relativistic monopoles based on the
non-observation of in-ice showers by the Radio Ice Cherenkov Experiment (RICE)
at the South Pole. We obtain a 95% C.L. limit of order 10^{-18}/(cm^2-s-sr) for
intermediate mass monopoles of 10^7<gamma<10^{12} at the anticipated energy
E=10^{16} GeV. This bound is over an order of magnitude stronger than all
previously published experimental limits for this range of boost parameters
gamma, and exceeds two orders of magnitude improvement over most of the range.
We review the physics of radio detection, describe a Monte Carlo simulation
including continuous and stochastic energy losses, and compare to previous
experimental limits.Comment: 16 pages, 6 figures. Accepted for publication in Phys. Rev. D. Minor
revisions, including expanded discussion of monopole energy uncertaint
Muon-Induced Background Study for Underground Laboratories
We provide a comprehensive study of the cosmic-ray muon flux and induced
activity as a function of overburden along with a convenient parameterization
of the salient fluxes and differential distributions for a suite of underground
laboratories ranging in depth from 1 to 8 km.w.e.. Particular attention
is given to the muon-induced fast neutron activity for the underground sites
and we develop a Depth-Sensitivity-Relation to characterize the effect of such
background in experiments searching for WIMP dark matter and neutrinoless
double beta decay.Comment: 18 pages, 28 figure
Computation using Noise-based Logic: Efficient String Verification over a Slow Communication Channel
Utilizing the hyperspace of noise-based logic, we show two string
verification methods with low communication complexity. One of them is based on
continuum noise-based logic. The other one utilizes noise-based logic with
random telegraph signals where a mathematical analysis of the error probability
is also given. The last operation can also be interpreted as computing
universal hash functions with noise-based logic and using them for string
comparison. To find out with 10^-25 error probability that two strings with
arbitrary length are different (this value is similar to the error probability
of an idealistic gate in today's computer) Alice and Bob need to compare only
83 bits of the noise-based hyperspace.Comment: Accepted for publication in European Journal of Physics B (November
10, 2010
ЕФЕКТИВНІСТЬ ІНГАЛЯЦІЙНИХ ГЛЮКОКОРТИКОСТЕРО ДІВ ПРИ РІЗНИХ ЗАПАЛЬНИХ ФЕНОТИПАХ БРОНХІАЛЬНО АСТМИУДІТЕЙ ШКІЛЬНОГО ВІКУ
In terms of clinical- epidemiologic evaluation of effectiveness of monotherapy of childhood bronchial asthma by inhalation corticosteroids, their greater effect has been determined under eosinophilic type of bronchial inflammation, but insufficiency of asthma control in presents of neutrophilic inflammatory process of airways.На основании проведенной клинико-эпидемиологической оценки эффективности монотерапии бронхиальной астмы у детей ингаляционными глюкокортикостероидами отмечено более выраженное их действие при эозинофильном типе воспаления дыхательных путей, но недостаточный уровень контролированности заболевания при нейтрофильном воспалительном ответе бронхов.На підставі проведено клініко-епідеміологічно оцінки результатів монотерапі бронхіально астми у дітей інгаляційними глюкокортикостеро дами відмічено х виразнішу клінічну ефективність при еозинофільному типі запалення дихальних шляхів, проте недостатній рівень контрольованості захворювання при нейтрофільній запальній відповіді бронхів
Use of singular classical solutions for calculation of multiparticle cross sections in field theory
A method of reducing the problem of the calculation of tree multiparticle
cross sections in theory to the solution of a singular classical
Euclidean boundary value problem is introduced. The solutions are obtained
numerically in terms of the decomposition in spherical harmonics, and the
corresponding estimates of the tree cross sections at arbitrary energies are
found. Numerical analysis agrees with analytical results obtained earlier in
the limiting cases of large and small energies.Comment: LaTeX, 18 pages, 3 postscript figure
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