Smooth and fast versus instantaneous quenches in quantum field theory

We examine in detail the relationship between smooth fast quantum quenches, characterized by a time scale $\delta t$, and {\em instantaneous quenches}, within the framework of exactly solvable mass quenches in free scalar field theory. Our earlier studies \cite{dgm1,dgm2} highlighted that the two protocols remain distinct in the limit $\delta t \rightarrow 0$ because of the relation of the quench rate to the UV cut-off, i.e., $1/\delta t\ll\Lambda$ always holds in the fast smooth quenches while $1/\delta t\sim\Lambda$ for instantaneous quenches. Here we study UV finite quantities like correlators at finite spatial distances and the excess energy produced above the final ground state energy. We show that at late times and large distances (compared to the quench time scale) the smooth quench correlator approaches that for the instantaneous quench. At early times, we find that for small spatial separation and small $\delta t$, the correlator scales universally with $\delta t$, exactly as in the scaling of renormalized one point functions found in earlier work. At larger separation, the dependence on $\delta t$ drops out. The excess energy density is finite (for finite $m\delta t$) and scales in a universal fashion for all $d$. However, the scaling behaviour produces a divergent result in the limit $m\delta t \rightarrow 0$ for $d\ge4$, just as in an instantaneous quench, where it is UV divergent for $d \geq 4$. We argue that similar results hold for arbitrary interacting theories: the excess energy density produced is expected to diverge for scaling dimensions $\Delta > d/2$.Comment: 52 pages; v2: minor modifications to match published versio

On the steady streaming flow due to high-frequency vibration in nearly inviscid liquid bridges

The steady streaming flow due to vibration in capillary bridges is considered in the limiting case when both the capillary Reynolds number and the non-dimensional vibration frequency (based on the capillary time) are large. An asymptotic model is obtained that provides the streaming flow in the bulk, outside the thin oscillatory boundary layers near the disks and the interface. Numerical integration of this model shows that several symmetric and non-symmetric streaming flow patterns are obtained for varying values of the vibration parameters. As a by-product, the quantitative response of the liquid bridge to high-frequency axial vibrations of the disks is also obtained

Multiscale permutation entropy analysis of laser beam wandering in isotropic turbulence

We have experimentally quantified the temporal structural diversity from the coordinate fluctuations of a laser beam propagating through isotropic optical turbulence. The main focus here is on the characterization of the long-range correlations in the wandering of a thin Gaussian laser beam over a screen after propagating through a turbulent medium. To fulfill this goal, a laboratory-controlled experiment was conducted in which coordinate fluctuations of the laser beam were recorded at a sufficiently high sampling rate for a wide range of turbulent conditions. Horizontal and vertical displacements of the laser beam centroid were subsequently analyzed by implementing the symbolic technique based on ordinal patterns to estimate the well-known permutation entropy. We show that the permutation entropy estimations at multiple time scales evidence an interplay between different dynamical behaviors. More specifically, a crossover between two different scaling regimes is observed. We confirm a transition from an integrated stochastic process contaminated with electronic noise to a fractional Brownian motion with a Hurst exponent H = 5/6 as the sampling time increases. Besides, we are able to quantify, from the estimated entropy, the amount of electronic noise as a function of the turbulence strength. We have also demonstrated that these experimental observations are in very good agreement with numerical simulations of noisy fractional Brownian motions with a well-defined crossover between two different scaling regimes.Comment: 8 pages, 6 figure

An exactly solvable quench protocol for integrable spin models

Quantum quenches in continuum field theory across critical points are known to display different scaling behaviours in different regimes of the quench rate. We extend these results to integrable lattice models such as the transverse field Ising model on a one-dimensional chain and the Kitaev model on a two-dimensional honeycomb lattice using a nonlinear quench protocol which allows for exact analytical solutions of the dynamics. Our quench protocol starts with a finite mass gap at early times and crosses a critical point or a critical region, and we study the behaviour of one point functions of the quenched operator at the critical point or in the critical region as a function of the quench rate. For quench rates slow compared to the initial mass gap, we find the expected Kibble-Zurek scaling. In contrast, for rates fast compared to the mass gap, but slow compared to the inverse lattice spacing, we find scaling behaviour similar to smooth fast continuum quenches. For quench rates of the same order of the lattice scale, the one point function saturates as a function of the rate, approaching the results of an abrupt quench. The presence of an extended critical surface in the Kitaev model leads to a variety of scaling exponents depending on the starting point and on the time where the operator is measured. We discuss the role of the amplitude of the quench in determining the extent of the slow (Kibble-Zurek) and fast quench regimes, and the onset of the saturation.Comment: 54 pages, 13 figures; v2: added analytic argument for Kitaev mode

Informatic applications to generate and fix navigation files and seismic records (SEGY)

Se presentan cinco programas simples escritos en lenguaje JAVA con dos fines. El primer grupo de programas permite generar archivos de navegación de forma efectiva y rápida para utilizar en los casos en que los archivos Segy no tengan incorporados estos datos. Estos programas crean archivos de navegación, compatibles con el Kingdom Suite y el Generic Mapping Tools (GMT) a partir de los datos de localización de las líneas sísmicas y de los respectivos números de puntos de energización. También calculan datos estadísticos (longitud total de la línea, equidistancia entre puntos de explosión) a partir de los archivos de navegación generados. Esta información estadística permite determinar la calidad de las fuentes de datos de navegación consultadas (y compararlas si hay más de una). El segundo conjunto de programas permite arreglar dos tipos de errores identificados en los archivos Segy. El primero se caracteriza por un desfasaje en un sector del perfil sísmico que se atribuyó a la falta de datos en la traza ubicada justo antes del desfasaje. En el segundo tipo de error los archivos son totalmente ilegibles y se asumió que el inicio del perfil sísmico se localizaba en un posición intermedia del archivo.We present five programs written in the JAVA language with two purposes in mind. The first allows one to elaborate navigation files in an effective and rapid way to be used when the Segy files lack navigation data. These programs create navigation files compatible with the Kingdom Suite and the Generic Mapping Tools (GMT) from a database of the seismic line locations and their respective shot point numbers. It also calculates statistical data (total length, shot point equidistance) for each file generated, which helps determine the quality of the navigation data sources and compare among them for multiple files. The second set of programs allows one to fix two types of errors identified in the Segy files. The first is characterized by an offset within the seismic section that was attributed to lack of data in the trace just previous the offset. For second error the files were totally illegible and it is assumed that the beginning of the seismic section was somewhere in the middle of the file.Fil: Esteban, Federico Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Esteban, A. H.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin

Enlarging regions of the MSSM parameter space for large tan β via SUSY decays of the heavy Higgs bosons

In the Minimal Supersymmetric Standard Model (MSSM) searches for the heaviest CP-even and CP-odd Higgs H, A to tau-lepton pairs severely constrain the parameter region for large values of tan β and light Higgs bosons H, A. We demonstrate how the experimental constraint can be avoided by new decays to light third-generation sfermions, whose left-right couplings to H can be maximised in regions of large trilinear couplings Ab, Aτ for sbottoms and staus, or large supersymmetric (SUSY) Higgs mass μ for stops. Due to the tan β-enhancement in the production cross-sections via gluon-fusion and in association with bottom-quark pairs for H and A, we find that down-type sfermions, in particular, sbottoms perform a better job in allowing more parameter space than up-type sfermions such as stops, which require much larger values of μ to compensate for tan β. Vacuum stability as well as flavour observables constraints and direct searches for SUSY particles are imposed. We also associate the lightest CP-even Higgs with the observed 125 GeV SM-like Higgs and impose the experimental constraints from the LHC.Facultad de Ciencias ExactasInstituto de Física La Plat

Multilayer silica-methacrylate hybrid coatings prepared by sol–gel on stainless steel 316L: Electrochemical evaluation

AISI 316L stainless steel is a biocompatible alloy used in prosthetic devices for many years. However this alloy tends to suffer localized corrosion and needs external fixation to hard tissues. This work describes the development of a coating system of two layers with complementary properties. The inner layer is prepared using TEOS and MTES that has already shown good anticorrosion properties. The top layer is a new hybrid organic–inorganic coating prepared with TEOS, 3-methacryloxypropyl trimethoxysilane (MPS), and 2-hydroxyethyl methacrylate (HEMA). The properties of this sol let to produce a thick and porous coating formed by two interpenetrating (organic and inorganic) networks. This coating could be an excellent container for the later aggregate of bioactive particles as the following step in a future work based on its high thickness, plasticity and open structure to allow the electrolyte access to induce the formation of hydroxyapatite. The coating is electrochemically characterised in simulated body fluid at 37 °C after 1, 10 and 30 days of immersion by means of assays as electrochemical impedance spectroscopy (EIS) and polarization curves. The dual coating seems to join the best properties of the individual ones in time: their thickness restrict the passage of potentially toxic ions to the body fluid, the breakdown potential (Eb) remains high and far from the corrosion potential (Ecorr) and the film presents the open structure of the outer layer that allows the entrance of the electrolyte to react with the particles when added to the sol meanwhile the inner layer maintain its corrosion protective features.Peer reviewe

Asymptotic structure of spacetime and the Newman-Penrose formalism: A brief review

A brief review about the Newman-Penrose formalism and the asymptotic structure of the spacetime is given. The goal of this review is to describe the latest developments in these topics and make a summary of the most important articles published by Newman and collaborators. Additionally, we discuss some aspects of this approach, and we compute the spin coefficients and the Weyl scalars for a general stationary axisymmetric spacetimes in a tetrad basis different from that defined by the principal null geodesic directions.Fil: Gómez López, L. A.. Universidad Industrial Santander; ColombiaFil: Quiroga, Gonzalo Damián. Universidad Industrial Santander; Colombia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin