8,205 research outputs found
A coherent state approach to effective potential in noncommutative D=(2+1) models
In this work we study the effective potential in noncommutative
three-dimensional models where the noncommutativity is introduced through the
coherent state approach. We discuss some important characteristics that seem to
be typical to this approach, specially the behavior of the quantum corrections
in the small noncommutativity limit.Comment: revtex4, 8 pages, 2 figures
On the duality in four-dimensional Lorentz-breaking field theories
We consider new issues of duality in four-dimensional Lorentz-breaking field
theories. In particular, we demonstrate that the arising of the aether-like
Lorentz-breaking term is necessary in order for the 4D models to display the
duality analog between the MCS and self-dual models in 3D. We further study the
dispersion relations in both theories and discuss the physical contents of the
models involved in this new dualilty.Comment: 16 page
Power-law statistics and stellar rotational velocities in the Pleiades
In this paper we will show that, the non-gaussian statistics framework based
on the Kaniadakis statistics is more appropriate to fit the observed
distributions of projected rotational velocity measurements of stars in the
Pleiades open cluster. To this end, we compare the results from the
and -distributions with the Maxwellian.Comment: 13 pages, 3 figure
Five-Dimensional QED, Muon Pair Production and Correction to the Coulomb Potential
We consider QED in five dimensions in a configuration where matter is
localized on a 3-brane while foton propagates in the bulk. The idea is to
investigate the effects of the Kaluza-Klein modes of the photon in the
relativistic regime, but in low energy, and in the nonrelativistic regime. In
the relativistic regime, we calculate the cross section for the reaction . We compare our theoretical result with a precise
measurement of this cross section at GeV. As result, we
extract a lower bound on the size of the extra dimension. In the
nonrelativistic regime, we derive the contribution for the Coulomb potential
due to the whole tower of the Kaluza-Klein excited modes of the photon. We use
the modified potential to calculate the Rutherford scattering differential
cross section.Comment: minor changes, three new refs. added, to appear in IJMP
Experimental and theoretical evidences for the ice regime in planar artificial spin ices
In this work, we explore a kind of geometrical effect in the thermodynamics
of artificial spin ices (ASI). In general, such artificial materials are
athermal. Here, We demonstrate that geometrically driven dynamics in ASI can
open up the panorama of exploring distinct ground states and thermally magnetic
monopole excitations. It is shown that a particular ASI lattice will provide a
richer thermodynamics with nanomagnet spins experiencing less restriction to
flip precisely in a kind of rhombic lattice. This can be observed by analysis
of only three types of rectangular artificial spin ices (RASI). Denoting the
horizontal and vertical lattice spacings by a and b, respectively, then, a RASI
material can be described by its aspect ratio =a/b. The rhombic lattice
emerges when =. So, by comparing the impact of thermal
effects on the spin flips in these three appropriate different RASI arrays, it
is possible to find a system very close to the ice regime
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