2,719 research outputs found
Constraining New Physics with D meson decays
Latest Lattice results on form factors evaluation from first principles
show that the standard model (SM) branching ratios prediction for the leptonic
decays and the semileptonic SM branching ratios of the
and meson decays are in good agreement with the world average
experimental measurements. It is possible to disprove New Physics hypothesis or
find bounds over several models beyond the SM. Using the observed leptonic and
semileptonic branching ratios for the D meson decays, we performed a combined
analysis to constrain non standard interactions which mediate the transition. This is done either by a model independent way through
the corresponding Wilson coefficients or in a model dependent way by finding
the respective bounds over the relevant parameters for some models beyond the
standard model. In particular, we obtain bounds for the Two Higgs Doublet Model
Type-II and Type III, the Left-Right model, the Minimal Supersymmetric Standard
Model with explicit R-Parity violation and Leptoquarks. Finally, we estimate
the transverse polarization of the lepton in the decay and we found it
can be as high as .Comment: 28 pages, 8 figures, 3 tables. Improved and extended analysis with
updated form factors from Lattice QC
The origin of non-classical effects in a one-dimensional superposition of coherent states
We investigate the nature of the quantum fluctuations in a light field created by the superposition of coherent fields. We give a physical explanation (in terms of Wigner functions and phase-space interference) why the 1-D superposition of coherent states in the direction of the x-quadrature leads to the squeezing of fluctuations in the y-direction, and show that such a superposition can generate the squeezed vacuum and squeezed coherent states
Effective cross-Kerr nonlinearity and robust phase gates with trapped ions
We derive an effective Hamiltonian that describes a cross-Kerr type
interaction in a system involving a two-level trapped ion coupled to the
quantized field inside a cavity. We assume a large detuning between the ion and
field (dispersive limit) and this results in an interaction Hamiltonian
involving the product of the (bosonic) ionic vibrational motion and field
number operators. We also demonstrate the feasibility of operation of a phase
gate based on our hamiltonian. The gate is insensitive to spontaneous emission,
an important feature for the practical implementation of quantum computing.Comment: Included discussion of faster gates (Lamb-Dicke regime), Corrected
typos, and Added reference
Scattering processes could distinguish Majorana from Dirac neutrinos
It is well known that Majorana neutrinos have a pure axial neutral current
interaction while Dirac neutrinos have the standard vector-axial interaction.
In spite of this crucial difference, usually Dirac neutrino processes differ
from Majorana processes by a term proportional to the neutrino mass, resulting
in almost unmeasurable observations of this difference. In the present work we
show that once the neutrino polarization evolution is considered, there are
clear differences between Dirac and Majorana scattering on electrons. The
change of polarization can be achieved in astrophysical environments with
strong magnetic fields. Furthermore, we show that in the case of unpolarized
neutrino scattering onto polarized electrons, this difference can be relevant
even for large values of the neutrino energy.Comment: 12 pages, 5 figure
Coherent states superpositions in cavity quantum electrodynamics with trapped ions
We investigate how superpositions of motional coherent states naturally arise
in the dynamics of a two-level trapped ion coupled to the quantized field
inside a cavity. We extend our considerations including a more realistic set up
where the cavity is not ideal and photons may leak through its mirrors. We
found that a detection of a photon outside the cavity would leave the ion in a
pure state. The statistics of the ionic state still keeps some interference
effects that might be observed in the weak coupling regime.Comment: Figure and typos correcte
Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 (Coleoptera, Carabidae, Trechini) a hypogean species from the south of the Iberian peninsula. Morphology, new taxonomic placement, systematics and biology
Se ha descubierto Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 en dos nuevas localidades del término municipal de Siles (Jaén, España): la Sima Curva del Espino y la Sima de los 30 Años, a poco más de 10 y 17 km de la localidad tÃpo, respectivamente. El estudio de numerosos ejemplares ha posibilitado realizar numerosas disecciones, preparaciones microscópicas y un estudio de microscopÃa electrónica, lo que ha ampliado el conocimiento anatómico de esta especie. La aplicación de técnicas de evaginación del endofalo, ha permitido estudiar con más detalle las piezas esclerotizadas, y proponer la reubicación de esta especie dentro del género Trechus Clairville 1806: Trechus (Trechus) lencinai (Mateu & Ortuño, 2006) n. comb. Aunque esta especie presenta caracteres de los grupos T. fulvus y T. pyrenaeus, el saco interno se asemeja más al de ciertas especies de los grupos T. quadristriatus y T. tingitanus. En este sentido, la especie no ha podido ser asignada a ningún grupo de especies de los propuestos por Jeannel. Se aportan algunos datos sobre su biologÃa (distribución temporal y espacial) y la entomofauna acompañante.Se ha descubierto Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 en dos nuevas localidades del término municipal de Siles (Jaén, España): la Sima Curva del Espino y la Sima de los 30 Años, a poco más de 10 y 17 km de la localidad tÃpo, respectivamente. El estudio de numerosos ejemplares ha posibilitado realizar numerosas disecciones, preparaciones microscópicas y un estudio de microscopÃa electrónica, lo que ha ampliado el conocimiento anatómico de esta especie. La aplicación de técnicas de evaginación del endofalo, ha permitido estudiar con más detalle las piezas esclerotizadas, y proponer la reubicación de esta especie dentro del género Trechus Clairville 1806: Trechus (Trechus) lencinai (Mateu & Ortuño, 2006) n. comb. Aunque esta especie presenta caracteres de los grupos T. fulvus y T. pyrenaeus, el saco interno se asemeja más al de ciertas especies de los grupos T. quadristriatus y T. tingitanus. En este sentido, la especie no ha podido ser asignada a ningún grupo de especies de los propuestos por Jeannel. Se aportan algunos datos sobre su biologÃa (distribución temporal y espacial) y la entomofauna acompañante.Duvalius (Duvalius) lencinai Mateu & Ortuño, 2006 was discovered in two new localities in the municipal district of Siles (Jaen, Spain): Sima Curva del Espino and Sima de los 30 Años, approximately 10 and 17 km, respectively, away from the type locality. The study of several individuals through dissection and use of optic and electronic microscopic preparations has increased the knowledge of the anatomy of this species. Evagination of the internal sac allowed further study of the sclerotized structures and led to the proposal of a new placement for this species within the genus Trechus Clairville 1806: Trechus (Trechus) lencinai (Mateu & Ortuño, 2006) n. comb. Although it comprises characters of the T. fulvus group and the T. pyrenaeus group, the endophallus is more similar to several species of the T. quadristriatus group and the T. tingitanus group. It could not therefore be placed in any of the species groups proposed by Jeannel. Some data about its biology (temporal and spatial distribution) and accompanying arthropod fauna are given
Analytical operator solution of master equations describing phase-sensitive processes
We present a method of solving master equations which may describe, in their
most general form, phase sensitive processes such as decay and amplification.
We make use of the superoperator technique.Comment: 10 pages, LaTex, 3 figures, accepted for publication in International
Journal of Modern Physics
A USB3.0 FPGA Event-based Filtering and Tracking Framework for Dynamic Vision Sensors
Dynamic vision sensors (DVS) are frame-free sensors
with an asynchronous variable-rate output that is ideal for hard
real-time dynamic vision applications under power and latency
constraints. Post-processing of the digital sensor output can
reduce sensor noise, extract low level features, and track objects
using simple algorithms that have previously been implemented
in software. In this paper we present an FPGA-based framework
for event-based processing that allows uncorrelated-event noise
removal and real-time tracking of multiple objects, with dynamic
capabilities to adapt itself to fast or slow and large or small
objects. This framework uses a new hardware platform based on
a Lattice FPGA which filters the sensor output and which then
transmits the results through a super-speed Cypress FX3 USB
microcontroller interface to a host computer. The packets of
events and timestamps are transmitted to the host computer at
rates of 10 Mega events per second. Experimental results are
presented that demonstrate a low latency of 10us for tracking
and computing the center of mass of a detected object.Ministerio de EconomÃa y Competitividad TEC2012-37868-C04-0
Triethylphosphite as a network forming agent enhances in-vitro biocompatibility and corrosion protection of hybrid organic-inorganic sol-gel coatings for Ti6Al4V alloys
The biocompatibility and life of metallic implants can be enhanced through improving the biocompatibility and corrosion protection characteristics of the coatings used with these materials. In this study, triethylphosphite (TEP) was used to introduce phosphorus into organic-inorganic hybrid silica based sol gel coatings prepared using γ-methacryloxypropyltrimethoxysilane and tetramethylorthosilicate. Addition of TEP dramatically increased the rate of intermolecular condensation and resulted in materials showing greater cross linking. Protein (fibrinogen) uptake, osteoblast in vitro biocompatibility and corrosion resistance was enhanced in coatings containing TEP. Although higher concentrations of phosphorus supported the greatest improvement in biocompatibility, a compromise in the phosphorus concentration used would be required if corrosion resistance was most desirable parameter for optimisation. Films prepared by dip coating on Ti6Al4V alloys from these sols offer a promising alternative to wholly metallic prostheses
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