55,211 research outputs found
Searching for a dark matter coupling to the Standard Model with a Stueckelberg extension
We investigate a double extension to the Standard Model (SM). A first
extension introduces, via minimal coupling, a massive boson. This enlarged
SM is coupled to a dark matter sector through the Stueckelberg mechanism by a
boson. However, the boson does not interact directly with the SM
fermions. In our study, we found that the is a massless photon-like
particle in dark sector. Constraints on the mass for and corrections to
mass are obtained.Comment: Presented at IWARA 2011. "Fifth International Workshop on Astronomy
and Relativistic Astrophysics" Jo\~ao Pessoa, Brazil, October 9 to 12, 201
Kinklike structures in scalar field theories: from one-field to two-field models
In this paper we study the possibility of constructing two-field models from
one-field models. The idea is to start with a given one-field model and use the
deformation procedure to generate another one-field model, and then couple the
two one-field models nontrivially, to get to a two-field model, together with
some explicit topological solutions. We show with several distinct examples
that the procedure works nicely and can be used generically.Comment: 8 pages; version to appear in Phys. Lett.
Massive "spin-2" theories in arbitrary dimensions
Here we show that in arbitrary dimensions there are two families of
second order Lagrangians describing massive "spin-2" particles via a
nonsymmetric rank-2 tensor. They differ from the usual Fierz-Pauli theory in
general. At zero mass one of the families is Weyl invariant. Such massless
theory has no particle content in and gives rise, via master action, to a
dual higher order (in derivatives) description of massive spin-2 particles in
where both the second and the fourth order terms are Weyl invariant,
contrary to the linearized New Massive Gravity. However, only the fourth order
term is invariant under arbitrary antisymmetric shifts. Consequently, the
antisymmetric part of the tensor propagates at large momentum as
instead of . So, the same kind of obstacle for the
renormalizability of the New Massive Gravity reappears in this nonsymmetric
higher order description of massive spin-2 particles.Comment: 11 pages, 0 figure
Massive spin-2 particles via embedment of the Fierz-Pauli equations of motion
Here we obtain alternative descriptions of massive spin-2 particles by an
embedding procedure of the Fierz-Pauli equations of motion. All models are free
of ghosts at quadratic level although most of them are of higher order in
derivatives. The models that we obtain can be nonlinearly completed in terms of
a dynamic and a fixed metric. They include some massive gravities
recently considered in the literature. In some cases there is an infrared (no
derivative) modification of the Fierz-Pauli mass term altogether with higher
order terms in derivatives. The analytic structure of the propagator of the
corresponding free theories is not affected by the extra terms in the action as
compared to the usual second order Fierz-Pauli theory.Comment: 13 page
Density-Dependent Synthetic Gauge Fields Using Periodically Modulated Interactions
We show that density-dependent synthetic gauge fields may be engineered by
combining periodically modu- lated interactions and Raman-assisted hopping in
spin-dependent optical lattices. These fields lead to a density- dependent
shift of the momentum distribution, may induce superfluid-to-Mott insulator
transitions, and strongly modify correlations in the superfluid regime. We show
that the interplay between the created gauge field and the broken sublattice
symmetry results, as well, in an intriguing behavior at vanishing interactions,
characterized by the appearance of a fractional Mott insulator.Comment: 5 pages, 5 figure
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