64,013 research outputs found
Meson decay in a corrected model
Extensively applied to both light and heavy meson decay and standing as one
of the most successful strong decay models is the model, in which
pair production is the dominant mechanism. The pair production can
be obtained from the non-relativistic limit of a microscopic interaction
Hamiltonian involving Dirac quark fields. The evaluation of the decay amplitude
can be performed by a diagrammatic technique for drawing quark lines. In this
paper we use an alternative approach which consists in a mapping technique, the
Fock-Tani formalism, in order to obtain an effective Hamiltonian starting from
same microscopic interaction. An additional effect is manifest in this
formalism associated to the extended nature of mesons: bound-state corrections.
A corrected is obtained and applied, as an example, to
and decays.Comment: 3 figures. To appear in Physical Review
The fully kinetic Biermann battery and associated generation of pressure anisotropy
The dynamical evolution of a fully kinetic, collisionless system with imposed
background density and temperature gradients is investigated analytically. The
temperature gradient leads to the generation of temperature anisotropy, with
the temperature along the gradient becoming larger than that in the direction
perpendicular to it. This causes the system to become unstable to pressure
anisotropy driven instabilities, dominantly to electron Weibel. When both
density and temperature gradients are present and non-parallel to each other,
we obtain a Biermann-like linear in time magnetic field growth. Accompanying
particle in cell numerical simulations are shown to confirm our analytical
results.Comment: 5 pages, 2 figures, + Supplementary materials (4 pages, 2 figures
Temperature dependence of antiferromagnetic susceptibility in ferritin
We show that antiferromagnetic susceptibility in ferritin increases with
temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when
taken as the derivative of the magnetization at high fields (
Oe). This behavior contrasts with the decrease in temperature previously found,
where the susceptibility was determined at lower fields ( Oe). At
high fields (up to Oe) the temperature dependence of the
antiferromagnetic susceptibility in ferritin nanoparticles approaches the
normal behavior of bulk antiferromagnets and nanoparticles considering
superantiferromagnetism, this latter leading to a better agreement at high
field and low temperature. The contrast with the previous results is due to the
insufficient field range used ( Oe), not enough to saturate the
ferritin uncompensated moment.Comment: 7 pages, 7 figures, accepted in Phys. Rev.
Combining Physical galaxy models with radio observations to constrain the SFRs of high-z dusty star forming galaxies
We complement our previous analysis of a sample of z~1-2 luminous and
ultra-luminous infrared galaxies ((U)LIRGs), by adding deep VLA radio
observations at 1.4 GHz to a large data-set from the far-UV to the sub-mm,
including Spitzer and Herschel data. Given the relatively small number of
(U)LIRGs in our sample with high S/N radio data, and to extend our study to a
different family of galaxies, we also include 6 well sampled near IR-selected
BzK galaxies at z~1.5. From our analysis based on the radiative transfer
spectral synthesis code GRASIL, we find that, while the IR luminosity may be a
biased tracer of the star formation rate (SFR) depending on the age of stars
dominating the dust heating, the inclusion of the radio flux offers
significantly tighter constraints on SFR. Our predicted SFRs are in good
agreement with the estimates based on rest-frame radio luminosity and the Bell
(2003) calibration. The extensive spectro-photometric coverage of our sample
allows us to set important constraints on the SF history of individual objects.
For essentially all galaxies we find evidence for a rather continuous SFR and a
peak epoch of SF preceding that of the observation by a few Gyrs. This seems to
correspond to a formation redshift of z~5-6. We finally show that our physical
analysis may affect the interpretation of the SFR-M* diagram, by possibly
shifting, with respect to previous works, the position of the most dust
obscured objects to higher M* and lower SFRs.Comment: 26 pages, 15 figures, 3 tables, accepted for publication in MNRAS on
Dec. 4th, 201
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