64,476 research outputs found
On the exposure to mobile phone radiation in trains
This report presents theoretical estimates of the Power Density levels which
may be reached inside trains. Two possible sources of high levels of radiation
are discussed. The first one arises since the walls of the wagons are metallic
and therefore bounce back almost all radiation impinging on them. The second is
due to the simultaneous emission of a seemingly large number of nearby
telephones. The theoretical study presented here shows that Power Densities
stay at values below reference levels always.Comment: 9 pages, 1 figur
New solutions of the D-dimensional Klein-Gordon equation via mapping onto the nonrelativistic one-dimensional Morse potential
New exact analytical bound-state solutions of the D-dimensional Klein-Gordon
equation for a large set of couplings and potential functions are obtained via
mapping onto the nonrelativistic bound-state solutions of the one-dimensional
generalized Morse potential. The eigenfunctions are expressed in terms of
generalized Laguerre polynomials, and the eigenenergies are expressed in terms
of solutions of irrational equations at the worst. Several analytical results
found in the literature, including the so-called Klein-Gordon oscillator, are
obtained as particular cases of this unified approac
CP violation with a dynamical Higgs
We determine the complete set of independent gauge and gauge-Higgs CP-odd
effective operators for the generic case of a dynamical Higgs, up to four
derivatives in the chiral expansion. The relation with the linear basis of
dimension six CP-odd operators is clarified. Phenomenological applications
include bounds inferred from electric dipole moment limits, and from present
and future collider data on triple gauge coupling measurements and Higgs
signals.Comment: 41 pages, 3 figures; V2: citations added, typos corrected, version
published on JHE
Physical Properties of OSIRIS-REx Target Asteroid (101955) 1999 RQ36 derived from Herschel, ESO-VISIR and Spitzer observations
In September 2011, the Herschel Space Observatory performed an observation
campaign with the PACS photometer observing the asteroid (101955) 1999 RQ36 in
the far infrared. The Herschel observations were analysed, together with ESO
VLT-VISIR and Spitzer-IRS data, by means of a thermophysical model in order to
derive the physical properties of 1999 RQ36. We find the asteroid has an
effective diameter in the range 480 to 511 m, a slightly elongated shape with a
semi-major axis ratio of a/b=1.04, a geometric albedo of 0.045 +0.015/-0.012,
and a retrograde rotation with a spin vector between -70 and -90 deg ecliptic
latitude. The thermal emission at wavelengths below 12 micron -originating in
the hot sub-solar region- shows that there may be large variations in roughness
on the surface along the equatorial zone of 1999 RQ36, but further measurements
are required for final proof. We determine that the asteroid has a
disk-averaged thermal inertia of Gamma = 650 Jm-2s-0.5K-1 with a 3-sigma
confidence range of 350 to 950 Jm-2s-0.5K-1, equivalent to what is observed for
25143 Itokawa and suggestive that 1999 RQ36 has a similar surface texture and
may also be a rubble-pile in nature. The low albedo indicates that 1999 RQ36
very likely contains primitive volatile-rich material, consistent with its
spectral type, and that it is an ideal target for the OSIRIS-REx sample return
mission.Comment: Accepted for publication in Astronomy & Astrophysics, 9 pages, 7
figure
Higgs ultraviolet softening
We analyze the leading effective operators which induce a quartic momentum
dependence in the Higgs propagator, for a linear and for a non-linear
realization of electroweak symmetry breaking. Their specific study is relevant
for the understanding of the ultraviolet sensitivity to new physics. Two
methods of analysis are applied, trading the Lagrangian coupling by: i) a
"ghost" scalar, after the Lee-Wick procedure; ii) other effective operators via
the equations of motion. The two paths are shown to lead to the same effective
Lagrangian at first order in the operator coefficients. It follows a
modification of the Higgs potential and of the fermionic couplings in the
linear realization, while in the non-linear one anomalous quartic gauge
couplings, Higgs-gauge couplings and gauge-fermion interactions are induced in
addition. Finally, all LHC Higgs and other data presently available are used to
constrain the operator coefficients; the future impact of data via off-shell Higgs exchange and of vector boson fusion data is
considered as well. For completeness, a summary of pure-gauge and gauge-Higgs
signals exclusive to non-linear dynamics at leading-order is included.Comment: 31 pages, 3 figures, 7 table
Magnetization reversal and anomalous coercive field temperature dependence in MnAs epilayers grown on GaAs(100) and GaAs(111)B
The magnetic properties of MnAs epilayers have been investigated for two
different substrate orientations: GaAs(100) and GaAs(111). We have analyzed the
magnetization reversal under magnetic field at low temperatures, determining
the anisotropy of the films. The results, based on the shape of the
magnetization loops, suggest a domain movement mechanism for both types of
samples. The temperature dependence of the coercivity of the films has been
also examined, displaying a generic anomalous reentrant behavior at T200 K.
This feature is independent of the substrate orientation and films thickness
and may be associated to the appearance of new pinning centers due to the
nucleation of the -phase at high temperatures.Comment: 9 pages, 7 figure
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