298 research outputs found
General Focus Point in the MSSM
The minimal supersymmetric extension of the Standard Model (SM) is a well
motivated scenario for physics beyond the SM, which allows a perturbative
description of the theory up to scales of the order of the Grand Unification
scale, where gauge couplings unify. The Higgs mass parameter is insensitive to
the ultraviolet physics and is only sensitive to the scale of soft
supersymmetry breaking parameters. Present collider bounds suggest that the
characteristic values of these parameters may be significantly larger than the
weak scale. Large values of the soft breaking parameters, however, induce large
radiative corrections to the Higgs mass parameter and therefore the proper
electroweak scale may only be obtained by a fine tuned cancellation between the
square of the holomorphic \mu-parameter and the Higgs supersymmetry breaking
square mass parameter. This can only be avoided if there is a correlation
between the scalar and gaugino mass parameters, such that the Higgs
supersymmetry breaking parameter remains of the order of the weak scale. The
scale at which this happens is dubbed as focus point. In this article, we
define the general conditions required for this to happen, for different values
of the messenger scale at which supersymmetry breaking is transmitted to the
observable sector, and for arbitrary boundary conditions of the sfermion,
gaugino, and Higgs mass parameters. Specific supersymmetry breaking scenarios
in which these correlations may occur are also discussed.Comment: 19 pages, 9 figures, new refs. adde
Leptogenesis in Complex Hybrid Inflation
We study the transference of an initial leptonic charge contained in a
complex scalar field (waterfall field) at the end of the inflation to the
leptons of the standard model and then convert this leptonic charge in baryonic
charge by sphaleron process. The proposal is that this is done trough the decay
of the complex scalar field particles into the right-handed neutrino which in
turn decays into the left-handed lepton doublet and the Higgs field of the
standard model. It must be analyzed in what environment the transference is
done. We propose that the inflaton (the dominant energy density of the
universe) decay into ultrarelativistic fermions before the waterfall field
particles decay in the right-handed neutrino, leaving a thermalized bath where
the transference of the leptonic asymmetry can be achieved.Comment: 8 pages, 1 figure. Prepared for the AIP Conference Proceedings of the
III International Meeting on Gravitation and Cosmology, Morelia, Mexico, May
26-30, 200
in custodial warped space
Flavor physics experiments allow to probe the accuracy of the Standard Model
(SM) description at low energies, and are sensitive to new heavy gauge bosons
that couple to quarks and leptons in a relevant way. The apparent anomaly in
the ratios of the decay of -mesons into -mesons and different lepton
flavors, is particularly intriguing, since these decay
processes occur at tree-level in the SM. Recently, it has been suggested that
this anomaly may be explained by new gauge bosons coupled to right-handed
currents of quarks and leptons, involving light right-handed neutrinos. In this
work we present a well-motivated ultraviolet complete realization of this idea,
embedding the SM in a warped space with an bulk gauge symmetry. Besides providing a solution to the hierarchy
problem, we show that this model, which has an explicit custodial symmetry, can
explain the anomaly and at the same time allow for a solution
to the anomalies, related to the decay of -mesons into
-mesons and leptons, . In addition, a model prediction is an anomalous
value of the forward-backward asymmetry , driven by the coupling, in agreement with LEP data.Comment: 43 pages, 12 figures, 1 table; v2 added references; v3 typos removed
and added references. It matches the version published in Journal of High
Energy Physic
The Effective Theory of the Light Stop Scenario
Electroweak baryogenesis in the minimal supersymmetric extension of the
Standard Model may be realized within the light stop scenario, where the
right-handed stop mass remains close to the top-quark mass to allow for a
sufficiently strong first order electroweak phase transition. All other
supersymmetric scalars are much heavier to comply with the present bounds on
the Higgs mass and the electron and neutron electric dipole moments. Heavy
third generation scalars render it necessary to resum large logarithm
contributions to perform a trustable Higgs mass calculation. We have studied
the one--loop RGE improved effective theory below the heavy scalar mass scale
and obtained reliable values of the Higgs mass. Moreover, assuming a common
mass for all heavy scalar particles, and values of all gaugino
masses and the Higgsino mass parameter about the weak scale, and imposing gauge
coupling unification, a two-loop calculation yields values of the mass in the interval between three TeV and six hundred TeV. Furthermore for a
stop mass around the top quark mass, this translates into an upper bound on the
Higgs mass of about 150 GeV. The Higgs mass bound becomes even stronger, of
about 129 GeV, for the range of stop and gaugino masses consistent with
electroweak baryogenesis. The collider phenomenology implications of this
scenario are discussed in some detail.Comment: 28 pages, 13 figures, uses axodraw.sty; v2: To appear in JHE
Esophageal Stenting in the Setting of Malignancy
Esophageal cancer is often diagnosed at an advanced stage, with many patients
found to have locoregional or metastatic disease at time of diagnosis. Because
of this, cure may be unlikely, leading treatment efforts to focus more on
symptom palliation and improving patient quality of life. The majority of
patients with advanced disease suffer from some degree of dysphagia. Palliative
efforts are therefore directed at relieving dysphagia, allowing patients to
manage their oropharyngeal secretions, reduce aspiration risk, and maintain
caloric intake orally. A variety of endoscopic treatment modalities have been
utilized with these objectives in mind, with options determined by the location
and size of the tumor, as well as the patient's expected prognosis. In this
article, we review the use of endoscopically-placed stents for palliation in
patients with advanced esophageal cancer. We discuss the history of stent use in
such cases, as well as more recent developments in stent technology. We give an
overview of some of the more commonly used stents in practice, discuss the
technique of insertion, and survey the short- and long-term outcomes of stent
placement
Light Dark Matter and the Electroweak Phase Transition in the NMSSM
We analyze the stability of the vacuum and the electroweak phase transition
in the NMSSM close to the Peccei-Quinn symmetry limit. This limit contains
light Dark Matter (DM) particles with a mass significantly smaller than the
weak scale and also light CP-even and CP-odd Higgs bosons. Such light particles
lead to a consistent relic density and facilitate a large spin-independent
direct DM detection cross section, that may accommodate the recently reported
signatures at the DAMA and CoGeNT experiments. Studying the one-loop effective
potential at finite temperature, we show that when the lightest CP-even Higgs
mass is of the order of a few GeV, the electroweak phase transition tends to
become first order and strong. The inverse relationship between the
direct-detection cross-section and the lightest CP-even Higgs mass implies that
a cross-section of the order of 10 cm is correlated with a strong
first order phase transition.Comment: 28 Pages, 15 figure
Presentación
[ES] CEA es una prestigiosa asociación en Automática. Su organización, la calidad de sus actividades, el elenco de miembros
distinguidos y el enfoque internacional hacen que tenga unos pilares muy sólidos. La nueva Junta Directiva apoyará, sin duda, las
actividades de los numerosos Grupos Temáticos (GT). Para enriquecer estas actividades queremos potenciar las acciones inter
GTs buscando una mayor sinergia y cohesión.Balaguer Bernaldo De Quiros, C. (2018). Presentación. Revista Iberoamericana de Automática e Informática industrial. 15(4). http://hdl.handle.net/10251/142828OJSi15
3D reconstruction of magnetization from dichroic soft X-ray transmission tomography
The development of magnetic nanostructures for applications in spintronics requires methods capable of visualizing their magnetization. Soft X‐ray magnetic imaging combined with circular magnetic dichroism allows nanostructures up to 100–300 nm in thickness to be probed with resolutions of 20–40 nm. Here a new iterative tomographic reconstruction method to extract the three‐dimensional magnetization configuration from tomographic projections is presented. The vector field is reconstructed by using a modified algebraic reconstruction approach based on solving a set of linear equations in an iterative manner. The application of this method is illustrated with two examples (magnetic nano‐disc and micro‐square heterostructure) along with comparison of error in reconstructions, and convergence of the algorithm
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