200 research outputs found
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
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
Branon radiative corrections to collider physics and precision observables
In the context of brane-world scenarios, we study the effects produced by the
exchange of virtual massive branons. A one-loop calculation is performed which
generates higher-dimensional operators involving SM fields suppressed by powers
of the brane tension scale. We discuss constraints on this scenario from
colliders such as HERA, LEP and Tevatron and prospects for future detections at
LHC or ILC. The most interesting phenomenology comes from new four-particles
vertices induced by branon radiative corrections, mainly from four fermion
interactions. The presence of flexible branes modifies also the muon anomalous
magnetic moment and the electroweak precision observables.Comment: 23 pages, 4 figures, LaTe
Dark photon searches with atomic transitions
Dark matter could be made up of dark photons, massive but very light
particles whose interactions with matter resemble those of usual photons but
suppressed by a small mixing parameter. We analyze the main approaches to dark
photon interactions and how they can be applied to direct detection experiments
which test different ranges of masses and mixings. A new experiment based on
counting dark photons from induced atomic transitions in a target material is
proposed. This approach appears to be particularly appropriate for dark photon
detection in the meV mass range, extending the constraints in the mixing
parameter by up to eight orders of magnitude with respect to previous
experiments.Comment: 16 pages, 3 figure
Some model-independent phenomenological consequences of flexible brane worlds
In this work we will review the main properties of brane-world models with
low tension. Starting from very general principles, it is possible to obtain an
effective action for the relevant degrees of freedom at low energies (branons).
Using the cross sections for high-energy processes involving branons, we set
bounds on the different parameters appearing in these models. We also show that
branons provide a WIMP candidate for dark matter in a natural way. We consider
cosmological constraints on its thermal and non-thermal relic abundances. We
derive direct detection limits and compare those limits with the preferred
parameter region in the case in which the EGRET excess in the diffuse galactic
gamma rays is due to dark matter annihilation. Finally we will discuss the
constraints coming from the precision tests of the Standard Model and the muon
anomalous magnetic moment.Comment: 10 pages, 6 figures. Contribution to the Proceedings of the Second
International Conference on Quantum Theories and Renormalization Group in
Gravity and Cosmology, IRGAC 2006, Barcelona, 11-15 July, 200
The Newtonian limit at intermediate energies
We study the metric solutions for the gravitational equations in Modified
Gravity Models (MGMs). In models with negative powers of the scalar curvature,
we show that the Newtonian Limit (NL) is well defined as a limit at
intermediate energies, in contrast with the usual low energy interpretation.
Indeed, we show that the gravitational interaction is modified at low densities
or low curvatures.Comment: 4 pages, REVTeX 4; minor typos corrected, one reference adde
Branon search in hadronic colliders
In the context of the brane-world scenarios with compactified extra
dimensions, we study the production of brane fluctuations (branons) in hadron
colliders (, and ) in terms of the brane tension
parameter , the branon mass and the number of branons . From the
absence of monojets events at HERA and Tevatron (run I), we set bounds on these
parameters and we also study how such bounds could be improved at Tevatron (run
II) and the future LHC. The single photon channel is also analyzed for the two
last colliders.Comment: 17 pages, 10 figures, LaTeX. New comments and figures included. Final
version to appear in Phys. Rev.
Phenomenological implications of brane world scenarios with low tension
The recent proposal of theories with compactified large extra dimensions is
reviewed. We pay especial attention to brane world models with low tension
where the only relevant degrees of freedom at low energies are the Standard
Model (SM) particles and the branons, which are transversal brane oscillations.
By using an effective Lagrangian, we study some phenomenological consequences
of these scenarios in a model independent way.Comment: 8 pages, LaTeX uses aipproc, 2 figures. Talk given by A. Dobado in
the X Mexican School of Particles and Fields, Playa del Carmen, Mexico, 200
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