2,989 research outputs found
Large-scale magnetic fields from inflation in teleparallel gravity
Generation of large-scale magnetic fields in inflationary cosmology is
studied in teleparallelism, where instead of the scalar curvature in general
relativity, the torsion scalar describes the gravity theory. In particular, we
investigate a coupling of the electromagnetic field to the torsion scalar
during inflation, which leads to the breaking of conformal invariance of the
electromagnetic field. We demonstrate that for a power-law type coupling, the
current magnetic field strength of G on 1 Mpc scale can be
generated, if the backreaction effects and strong coupling problem are not
taken into consideration.Comment: 4 pages, no figure, to be published in the Proceedings of the "12th
Asia Pacific Physics Conference.
Inverse-Chirp Imprint of Gravitational Wave Signals in Scalar Tensor Theory
The scalar tensor theory contains a coupling function connecting the
quantities in the Jordan and Einstein frames, which is constrained to guarantee
a transformation rule between frames. We simulate the supernovae core collapse
with different choices of coupling functions defined over the viable region of
the parameter space and find that a generic inverse-chirp feature of the
gravitational waves in the scalar tensor scenario.Comment: 13 pages, 4 figures, revised version accepted by EPJ
Fano resonance in a normal metal/ferromagnet-quantum dot-superconductor device
We investigate theoretically the Andreev transport through a quantum dot
strongly coupled with a normal metal/ferromagnet and a superconductor
(N/F-QD-S), in which the interplay between the Kondo resonance and the Andreev
bound states (ABSs) has not been clearly clarified yet. Here we show that the
interference between the Kondo resonance and the ABSs modifies seriously the
lineshape of the Kondo resonance, which manifests as a Fano resonance. The
ferromagnetic lead with spin-polarization induces an effective field, which
leads to splitting both of the Kondo resonance and the ABSs. The
spin-polarization together with the magnetic field applied provides an
alternative way to tune the lineshape of the Kondo resonances, which is
dependent of the relative positions of the Kondo resonance and of the ABSs.
These results indicate that the interplay between the Kondo resonance and the
ABSs can significantly affect the Andreev transport, which could be tested by
experiments.Comment: 8pages, 7figure
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