Vol. 65 No. 5 Sept-Oct (2019): Revista Mexicana de Física

We present a review of Higgs physics in the SM and beyond, including the tests of the Higgs boson properties that have been performed at LHC and have permitted to delineate its profile. After presenting the essential features of the BEH mechanism, and its implementation in the SM, we
discuss how the Higgs mass limits developed over the years. These constraints in turn helped to classify the Higgs phenomenology (decays and production mechanisms), which provided the right direction to search for the Higgs particle, an enterprise that culminated with its discovery at
LHC. So far, the constraints on the couplings of the Higgs particle, point towards a SM interpretation. However, the SM has open ends that suggest the need to look for extensions of the model. We discuss in general the connection of the Higgs sector with some new physics (e.g. supersymmetry, flavor and Dark matter), with special focus on a more flavored Higgs sector. Thus is realized in the most general 2HDM, and its textured version, which we study in general, and for its various limits, which contain distinctive flavor-violating signals that could be searched at current and future colliders.

En este trabajo, se realizó un análisis cuantitativo de los metales pesados Cr y Cu en sedimentos fluviales mediante espectroscopia de ruptura inducida por láser (LIBS) para evaluar el antropogénico. Para realizar el análisis, se recolectaron diferentes muestras de sedimento en las posiciones seleccionadas. Se construyeron curvas de calibración de adición estándar para Cr y Cu midiendo la línea Cr I a 357.87 nm y la línea Cu I a 324.75 nm. Los contenidos de humedad y materia orgánica de los sedimentos fueron tomados en cuenta para superar el efecto matriz. Los modelos cuantitativos se evaluaron estadísticamente para evaluar la robustez y la capacidad de predicción del método. Los valores bajos de la raíz - medias - errores cuadrados para la calibración ( RMSEC ), la predicción ( RMSEP ) y la validación cruzada (RMSECV ) se calcularon. Se obtuvieron valores altos de los coeficientes de correlación de calibración ( R ² _c = 0.984 para Cr; R ² _c = 0.986 para Cu) y validación cruzada ( R ² _cv = 0.985 para Cr; R ² _cv = 0.981 para Cu). Los límites de detección calculados ( LoD ) fueron 2.9 ppm para Cr y 3.3 ppm para Cu, y los límites de cuantificación ( LoQ) fueron 9.5 ppm para Cr y 11 ppm para Cu. Las concentraciones de Cr y Cu superiores a los valores de referencia se obtuvieron en los sedimentos aguas abajo (Cr: 49 ppm, Cu: 81 ppm) que son indicativos de la contaminación de la cuenca por metales pesados debido al derrame de efluentes no tratados derivados de actividades antropogénicas. . El análisis LIBS se optimizó para el monitoreo confiable de metales pesados en sedimentos fluviales.

Many studies, focused in TiO₂ nanotubes obtained by anodization, uses frequently a NH₄F salt concentration from 0.3 – 0.5 wt% and the information about how voltage and time affects to nanotubes morphology, are valid for these concentration, moreover, this range induces a long time of anodized. TiO₂ nanotubes were prepared by anodization process of a set of titanium foils in order to study the influence of time and voltage on the morphology of them. The anodization process consists of an organic media of ethylene glycol and 1.2 wt% of NH₄F salts, voltage from 5 to 30 V for a time period from 1 to 6 hours, constant potential of 30 V for a time lapse from 10 to 360 minutes and 5 to 480 seconds. All anodized samples are rinsed and annealed to 400 °C by 3 hours to obtain an anatase crystalline structure. The morphological characterization was carried out by Field Emission Scanning Electron Microscopy (FESEM) to verify the presence of the nanostructures: nanopores, nanotubes and nanograss, these nanostructures were identified to appear for a time period from 5 to 480 seconds, 10 to 60 minutes and 1 to 6 hours, respectively. The surface morphology, inner diameter and length of the nanotubes varied with the electrochemical anodization parameters. Raman spectroscopy was used for optical characterization in order to identify the changes in signal intensity and Eg mode Shift and it was observed that intensity suffers an increment and E_g mode suffers a blue shift as a thickness function.

The electrospinning technique has been used to synthesize TiO₂ nanofibres, which by annealing at high temperatures in a wide range achieves the crystal phase transformation of anatase to rutile passing through the anatase+rutile mixed. The investigated temperature range was 0-1000°C. The TiO₂ nanofibres chemical stoichiometry and surface morphology were obtained by Scanning Electron Microscopy and Energy Dispersive Spectrometry. The nanofibres diameter was ranged from 137.0 to 115.3 nm in the annealing temperature interval of 0-1000°C. The influence of the annealing temperature on the structure and crystal phase quality of the TiO₂crystal has been investigated by X-ray diffraction and Raman scattering. Clear evidence of nanofibres structural transformation from pure anatase to pure rutile structures, including the quasi-amorphous and anatase+rutile mixed phases has been confirmed by Raman scattering. By X-ray diffraction was found that the nanofibres crystalline phases present as preferential growth direction (101) for anatase and (110) for rutile. The Raman spectroscopy exhibits the anomalous behaviour for band broadening and shifting of Raman bands with increasing crystallite size that form the nanofibres. The room-temperature photoluminescence presents radiative bands whose main band redshifts, from 2.56 to 1.32 eV, as the crystalline phase transforms in the investigated annealing temperature range.

Structural, elastic, electronic and magnetic properties of the quaternary Heusler alloys  are calculated using the full-potential linearized augmented plane wave (FP-LAPW) method in the framework of the density functional theory (DFT) and implemented in WIEN2k code. The exchange-correlation potential is evaluated using the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE) parameterization. Our theoretically results provide predictions for the mixed  in which no experimental and theoretical data are currently available. The lattice parameter and bulk modulus as well the elastic constants and their related elastic moduli for  have been calculated. Also, the electronic properties including density of states and band structures indicate the metallic character for . Morever, this quaternary Heusler alloy is found to be ferromagnetic, ductile and anisotropic in nature.

The new ordered vacancy compound Ag₃In₅Te₉ was synthesized by the melt and annealing technique and its structure was refined from X-ray powder diffraction pattern using the Rietveld method. The title compound crystallizes in the tetragonal space group P 2c (Nº 112), with a = 6.3453(2) Å, c = 12.5754(7) Å, V = 506.32(4) ų. The refinement of 23 instrumental and structural parameters led to R_p = 5.4%, R_wp = 5.8%, R_exp = 5.1 %, S = 1.1. This ternary compound is isostructural with Cu₃In₅Te₉ and have a defect adamantane structure.

This pagination specifies the characteristics of Carreau nano-fluid model embedded with hydro-magnetic (MHD) effects and the energy equation is extracted through Cattaneo-Christov approach. The process of heat generation and chemical reaction are also carried out whereas the fluid flow having infinite shear rate viscosity is induced by the stretching sheet. The mathematical form is developed in order to get the coupled partial differential equations and admissible similarity transforms are used to construct the set of ordinary differential equations and then sorted out numerically by applying Runge-Kutta Fehlberg method supported with shooting scheme. The graphs are plotted that portrays the impact of fluid velocity and temperature towards various engineering parameters which reveals that the fluid temperature increases when enlarging heat generation parameter. The validations for the numerical values of skin friction coefficient are delineated with the existing literature [33]. Also, the numerical findings for the local Nusselt number are offered.

Abstract. Two identical homemade prototypes are used to monitoring the tide levels on two strategic points of the Serinhaém estuary. This monitoring was realized along a period close to the new moon phase. From the analysis of the experimental results, the average height of the tide is determined between each period of high-tide and low-tide. These estimations show discrepancies minors than half order of magnitude, compared to the theoretical predictions of the static and dynamic oceanic tide models. Also the amplification effects of the tide in the estuary head can be quantified exhibiting a maximum gain 1.33, which is observed in the new moon phase.

Mathematically, the sphere unit S² is described to be a 2-sphere in an ordinary space with a positive curvature. In this study, we aim to present the manipulation of a spherical charged particle in a continuous motion with a magnetic field on the sphere S² while it is exposed to a frictional force. In other words, we effot to derive the exact geometric characterization for the spherical charged particle under the influence of a frictional force field on the unit 2-sphere. This approach also helps to discover some physical and kinematical characterizations belonging to the particle such as the magnetic motion, the torque, the potential energy functional, and the Poynting vector.

In this paper, the generalized exponential rational function method (GERFM) and the extended sinh-Gordon equation expansion method (ShGEEM) are used to construct exact solutions of the perturbed β-conformable-time Radhakrishnan-Kundu-Lakshmanan (RKL) equation. This model governs soliton propagation dynamics through a polarization-preserving fiber. 
Fractional derivatives are described in the β-conformable sense. As a result, we get new form of solitary traveling wave solutions for this model including novel soliton, traveling waves and kink-type solutions with complex structures. Physical interpretations of some extracted solutions are also included through taking suitable values of parameters and derivative order in them. It is proved that these methods are powerful, efficient, and can be fruitfully implemented to establish new solutions of nonlinear conformable-time partial differential equations applied in mathematical physics.

Using the semi-classical approximation to the Wheeler-DeWitt equation obtained via Arnowitt-Deser-Misner (ADM) formalism in the Friedmann-Lemaitre-Robertson-Walker (FLRW) model coupled to a scalar eld and positive cosmological constant, and in the Kantowski-Sachs (KS) Universe, we introduced a deformation on the commutation relation for the minisuperspace variables and find an explicit semiclassical expression equivalent, in an adequate limit, to the solution with the aid of asymptotically equal functions and the theory of Ultralters, oering a suggestive alternative to sketch the behavior of the dynamical system involved without the need to solve it numerically.

In this paper, the time fractional Kolmogorov-Petrovskii-Piskunov (FKP) equation is analyzed by means of Lie symmetry approach. The FKP is reduced to ordinary differential equation of fractional order via the attained point symmetries. Moreover, the simplest equation method is used in construct the exact solutions of underlying equation with recently introduced conformable fractional derivative.

We make a number of remarks on linearized gravity with cosmological constant in any dimension, which we argue, can be useful in a quantum gravity framework. For this purpose we assume that the background space-time metric corresponds to the de Sitter or anti-de Sitter space. Moreover, we make some interesting observations, putting special attention on the possible scenario of  a graviton-tachyon connection, via the graviton mass and the cosmological constant correspondence. We compare our proposed formalism with the Novello and Neves approach.

The mini-SciCR is a cosmic ray detector, it is made of scintillator bars with a total volume of 20 x 20 x 20.8 $cm^{3}$. The array of scintillator bars act both as a target and as a tracker of the incident radiation. In this paper we describe the method developed with the help of a Monte Carlo simulation to distiguish the neutron signals from gamma ray signals, it is based on the different maximum energy deposited at a scintillator bar by neutrons and gamma rays. To distiguish the neutral emission signals (neutrons and gamma rays) from charged particles signals, we implemented via software a system of anti-coincidence between edge bars and internal bars of the detector. We also report the flux of neutrons and gamma rays measured by the mini-SciCR at the top of the Sierra Negra volcano at 4,600 m.a.s.l., in Eastern Mexico. The mini-SciCR was operating from October 2010 to July 2012. We also present the Forbush decrease registered by the mini-SciCR on march, 2012. The mini-SciCR is a prototype of a new cosmic ray detector called SciBar Cosmic Ray Telescope installed in the same place, which is in the process of operation parameter tuning and calibration. The SciCRT will work mainly as a Solar Neutron and Muon Telescope.

The deposition of a high resistivity transparent (HRT) oxide between a transparent conductive oxide (TCO) and the window CdS has demonstrated the improvement of performance of CdS/CdTe solar cells, fabricated in the superstrate-configuration.  In this work the influence of the pneumatic spray pyrolysis (PSP) and magnetron sputtering techniques on the properties TCO/SnO₂/CdS structure through the deposition of the intermediate SnO₂ between the commercial conducting glass and CdS window is presented by means of X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and contact resistance, calculated using transmission line method (TLM), in order to reduce the front contact resistance in devices with superstrate-configuration. The results of this work are applicable to other solar cells in the same configuration as the recent solar cells based on the compound Sb₂Se₃, where the use of this type of HRT has not been studied.

Magnetic probes (also known as B-dot coil) are electromagnetic devices used to measure magnetic
eld variations in many frequency ranges. The measured magnetic eld frequency directly relates to
the elected method to make the B-dot coil calibration. This work presents a B-dot coil calibration in
a frequency range from 6.16 kHz to 36.63 kHz. An inductor L (Helmholtz coil) connects in parallel
with a variable capacitor bank Cvar to form a coupled LCvar resonant circuit. The LCvar circuit is
fed with a half bridge oscillator. The capacitance Cvar is varied until the circuit is in resonant state
at dierent frequencies. The resonant circuit produces sinusoidal oscillations in the aforemention
frequency band. The sensitivity is calculated by using voltage Vout of the B-dot coil and voltage
VH measured from Helmholtz terminals.

Radiation therapy is a promising treatment for cancer patients. The highest dose of radiation must deliver to tumor and the lowest to the healthy tissues. Since charged particles such as protons have high stopping-power at track-end, these particles can be used to treat tumors close to sensitive tissues. Formulas that commonly used for proton stopping-power in a soft tissue-equivalent material (T.E.) and each of its elements have respectively 48, and 12 constants. Due to the complexity of formulas, high number of constants, high occupancy of computer memory, and rounding error of computer, existing formulas reduces information processing speed. Because of the importance of proton therapy and its applications in dosimetry, microdosimetry, detectors, and computer simulations of these systems, it is necessary to use fast and accurate formulas for the stopping-power and range in the T.E., and its elements. We wrote a computer code in FORTRAN programming language, and used the fitting method and obtained simple and fairly accurate formulas for the proton range in these materials. Our range formula in T.E. have 6 constants, and in elements of T.E. include carbon, nitrogen, and oxygen have 4 and hydrogen have 8 constants. So our formulas greatly reduce the above mentioned errors.

The fusion cross section of $^{9}$Li + $^{70}$Zn reaction is studied
in an extensive manner within the framework of different theoretical
approaches. For this purpose, three different methods which consist
of proximity potentials, temperature dependent densities and
temperature dependent nuclear potentials are used in order to
determine the real part of the nuclear potential. The imaginary part
is considered as Woods-Saxon potential. The calculated fusion cross
sections are compared with the experimental data. The theoretical
results describe the experimental data very well. It is seen that
the applied approaches present to be different ways to study the
reactions involving fusion cross sections.

 In this work, a new application of digital speckle pattern shearing interferometry (shearography) for strain measurement is proposed. This optical technique is implemented to measure strain in elastic materials. Three different sealing elastomers were tested in short-term creep tests in order to assess creep compliance, which is an important mechanical property for viscoelastic materials. The creep tests were carried out applying a constant tensile load to a specimen. An in-plane shearography setup was implemented to measure the creep strains in the polymers. Results of creep strains were compared with that obtained with a commercial equipment of digital image correlation (DIC). Although some limitations were found for shearography, it was possible to verify the adaptability of this technique for strain measurement in elastomers.

Rev. Mex. Fis. 65 (5) 2019

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