62 research outputs found
QCD contributions to the thermal history of the early Universe
We discuss the deviations from the ideal relativistic thermal bath. These
deviations are dominated from quantum chromodynamic (QCD) corrections in the
most part of the parameter space of the Standard Model (SM) and the Minimal
Supersymmetric Standard Model (MSSM). These effects are relevant for
astrophysical precision measurements and dynamics of scalar tensor theories
(SST).Comment: To appear in the AIP proceedings of "Quark Confinement and Hadron
Spectrum IX" (QCHSIX), Madrid 30th August-3rd September 2010. 3 page
Whitepaper on Super-weakly Interacting Massive Particles for Snowmass 2013
Super-weakly interacting massive particles produced in the late decays of
weakly interacting massive particles (WIMPs) are generic in large regions of
supersymmetric parameter space and other frameworks for physics beyond the
standard model. If their masses are similar to that of the decaying WIMP, then
they could naturally account for all of the cosmological dark matter abundance.
Their astrophysical consequences and collider signatures are distinct and
different from WIMP candidates. In particular, they could modify Big Bang
Nucleosynthesis, distort the Cosmic Microwave Background, reduce galactic
substructure and lower central densities of low-mass galaxies.Comment: 4 pages, 2 figures, white paper for Snowmass 201
R^2 Dark Matter
There is a non-trivial four-derivative extension of the gravitational
spectrum that is free of ghosts and phenomenologically viable. It is the so
called -gravity since it is defined by the only addition of a term
proportional to the square of the scalar curvature. Just the presence of this
term does not improve the ultraviolet behaviour of Einstein gravity but
introduces one additional scalar degree of freedom that can account for the
dark matter of our Universe.Comment: 6 pages, 1 figure, to appear in the Proceedings of the sixth
International Workshop on the Dark Side of the Universe (DSU2010) Leon,
Guanajuato, Mexico 1-6 June 201
New torsion black hole solutions in Poincar\'e gauge theory
We derive a new exact static and spherically symmetric vacuum solution in the
framework of the Poincar\'e gauge field theory with dynamical massless torsion.
This theory is built in such a form that allows to recover General Relativity
when the first Bianchi identity of the model is fulfilled by the total
curvature. The solution shows a Reissner-Nordstr\"om type geometry with a
Coulomb-like curvature provided by the torsion field. It is also shown the
existence of a generalized Reissner-Nordstr\"om-de Sitter solution when
additional electromagnetic fields and/or a cosmological constant are coupled to
gravity.Comment: 14 pages, 0 figures, minor changes, references adde
QCD Effects in Cosmology
The cosmological evolution in the radiation dominated regimen is usually
computed by assuming an ideal relativistic thermal bath. In this note, we
discuss the deviation from the non-interaction assumption. In either the
standard model (SM) and the minimal supersymmetric standard model (MSSM), the
main contribution comes from the strong interaction. An understanding of these
effects are important for precision measurements and for the evolution of
scalar modes, where the commented corrections constitute the main source of the
dynamics.Comment: 4 pages, 2 figures. Contributed to CIPANP 2009: Tenth Conference on
the Intersections of Particle and Nuclear Physics, May 26-31, 2009, San
Diego, Californi
Extended Reissner-Nordstr\"om solutions sourced by dynamical torsion
We find a new exact vacuum solution in the framework of the Poincar\'e Gauge
field theory with massive torsion. In this model, torsion operates as an
independent field and introduces corrections to the vacuum structure present in
General Relativity. The new static and spherically symmetric configuration
shows a Reissner-Nordstr\"om-like geometry characterized by a spin charge. It
extends the known massless torsion solution to the massive case. The
corresponding Reissner-Nordstr\"om-de Sitter solution is also compatible with a
cosmological constant and additional U(1) gauge fields.Comment: 12 pages, 0 figures, minor changes, references adde
Einstein-Yang-Mills-Lorentz black holes
Different black hole solutions of the coupled Einstein-Yang-Mills equations
have been well known for a long time. They have attracted much attention from
mathematicians and physicists since their discovery. In this work, we analyze
black holes associated with the gauge Lorentz group. In particular, we study
solutions which identify the gauge connection with the spin connection. This
ansatz allows one to find exact solutions to the complete system of equations.
By using this procedure, we show the equivalence between the Yang-Mills-Lorentz
model in curved space-time and a particular set of extended gravitational
theories.Comment: 10 pages, 0 figures, minor changes, references added. It matches the
version published in Eur. Phys. J.
Correspondence between Einstein-Yang-Mills-Lorentz systems and dynamical torsion models
In the framework of Einstein-Yang-Mills theories, we study the gauge Lorentz
group and establish a particular correspondence between this case and a certain
class of theories with torsion within Riemann-Cartan space-times. This relation
is specially useful in order to simplify the problem of finding exact solutions
to the Einstein-Yang-Mills equations. The applicability of the method is
divided into two approaches: one associated with the Lorentz group SO(1,n-1) of
the space-time rotations and another one with its subgroup SO(n-2). Solutions
for both cases are presented by the explicit use of this correspondence and,
interestingly, for the last one by imposing on our ansatz the same kind of
rotation and reflection symmetry properties as for a nonvanishing space-time
torsion. Although these solutions were found in previous literature by a
different approach, our method provides an alternative way to obtain them and
it may be used in future research to find other exact solutions within this
theory.Comment: 10 pages, 0 figures, minor changes, references added. It matches the
version published in Phys. Rev.
Dark Matter and Higgs Sector
The inert doublet model is an extension of the Standard Model of Elementary
Particles that is defined by the only addition of a second Higgs doublet
without couplings to quarks or leptons. This minimal framework has been studied
for many reasons. In particular, it has been suggested that the new degrees of
freedom contained in this doublet can account for the Dark Matter of the
Universe.Comment: 6 pages, 3 figures,To appear in the Proceedings of the sixth
International Workshop on the Dark Side of the Universe (DSU2010) Leon,
Guanajuato, Mexico 1-6 June 201
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