Communications in Physics

In this paper, we present the results of the preparation of Surface Enhanced Raman Spectroscopy (SERS) substrates by depositing silver nanoparticles (Ag NPs) onto a porous silicon wafer that is produced by the chemical etching process. The influences of the preparation parameters such as resistivity of the silicon wafer, the anodizing current density, etching time to the size of pores were systematically investigated. The SERS substrates prepared were characterised by using appropriate techniques: the morphology and pores size by scanning electron microscope (SEM), the SERS activity by Raman scattering measure of organic molecules malachite green (MG) embedded into the substrate at room temperature. Our experimental results show that a home-made Raman microscope system could be efficiently used to detect the MG molecules at the concentration lower than 10-7 M with the prepared SERS substrates which have Ag NPs in the obtained pores of 10 – 40 nm.

The advent of electromagnetically induced transparency (EIT) offered a new coherent material with exotic and controllable optical properties. Although, studies on single-EIT are described in detail for single-EIT, however, extension from single- to multi- EIT is currently of current interest due to it gains advantages in multi-channel optical communication, waveguides for optical signal processing and multi-channel quantum information processing. In this work, we review recent research works concerning multi-EIT and some related applications, as controlling group velocity of light, giant Kerr nonlinearity, optical bistability. A special attention of the review also gives for analytical interpretations of EIT spectrum, its dispersion and related applications such as EIT enhanced Kerr nonlinearity and optical bistability to give physics insight. From experimental point of view, a latest development for measuring multi-EIT spectrum and its dispersion in hot medium is presented and compared to theoretical analytical representations.

We present a study of the polarization observables of the $W$ and $Z$ bosons in the process \(p p \to W^\pm Z\to e^\pm \nu_e \mu^+\mu^-\) at the 13 TeV Large Hadron Collider. The calculation is performed at next-to-leading order, including the full QCD corrections as well as the electroweak corrections, the latter being calculated in the double-pole approximation. The results are presented in the helicity coordinate system adopted by ATLAS and for different inclusive cuts on the di-muon invariant mass. We define left-right charge asymmetries related to the polarization fractions between the \(W^+ Z\) and \(W^- Z\) channels and we find that these asymmetries are large and sensitive to higher-order effects. Similar findings are also presented for charge asymmetries related to a P-even angular coefficient.

Monoclinic tungsten oxide (WO3) nanoplates were synthesized via a two-step simple process: acid precipitation at room temperature to prepare WO3.H2O nanoplates and annealing at high temperature (400 and 500 oC) in ambient air to obtain WO3 nanoplates. The effect of annealing temperature on physical properties (morphology, oxygen deficiency, crystallinity, optical properties, and photocatalytic activity) of WO3 nanoplates was studied. At both two studied annealing temperatures, all samples have the stable monoclinic structure and visible light-range optical bandgap, but the morphology and photocatalytic activity of the samples vary significantly with annealing temperature. At higher annealing temperature (500 oC), the sample has both nanoplate and nanograin morphologies with round edges, higher crystallinity, larger optical bandgap (2.71 eV), and lower photocatalytic activity. The sample annealed at 400 oC has nanoplate morphology with sharp edges, lower optical bandgap (2.63 eV), and higher photocatalytic which shows a high potential for photocatalytic application under visible light irradiation. The effect of the annealing temperature on the properties of  WO3 nanoplates is assigned to the dehydration, the coalescence, and/or the melting processes at high temperatures. Dehydration causes the formation of oxygen vacancy – oxygen deficiency. The coalescence and/or the melting result in the changing of morphology and the decrease of the oxygen vacancies. These results imply a simple, cost-effective method to prepare highly oxygen-deficient WO3 nanoplates.

The obtainable quality factor for a nano beam resonator is limited due to internal damping such as thermoelastic damping. Therefore, understanding how internal damping varies with the respective resonant modes is very important to design a high performance nanoresonator. In this research, we investigate thermoelastic damping depending on vibration modes of nano beam resonators using finite element method. The study results show that the quality factor of a nanoresonator is lower than at high order modes. The silicon nano beam resonator with the quality factor larger than one million can be achieved by optimizing the dimensions of the resonant beam.

This work is devoted for gauge boson sector of the recentlyproposed model based on \(\mathrm{SU}(3)_C\otimes \mathrm{SU}(3)_L\otimes \mathrm{U}(1)_X\) group with minimal content of leptons andHiggses. The limits on the masses of the bilepton gauge bosons andon the mixing angle among the neutral ones are deduced. Using theFritzsch anzats on quark mixing, we show that the third family ofquarks should  be different from the first two. We obtain a lowerbound on mass of the new heavy neutral gauge boson as 4.032 TeV.Using data on branching decay rates of the \(Z\) boson, we  can fix the limit to the \(Z\) and $Z^\prime$ mixing angle\(\phi\) as \(-0.001\le\phi\le 0.0003\).

It is explicitly shown that either the approximate solution of the integral equation for the inverse of the pion form facto,r or the result of the Pad\(\text{\'e}\) approximant method of resumming the one loop Chiral Perturbation Theory (CPTH) are equivalent to the standard vector meson dominance (VMD) models, using the vector meson coupling to two pseudoscalars given by the KSRF relation. Inconsistencies between the one loop CPTH and its unitarised version (or the VMD model) are pointed out. The situation is better for the CPTH calculation of the scalar form factor and the related S-wave $\pi \pi$ scattering. The branching ratios of \(\tau \to \pi^+ \pi^0 \nu \), \(\tau \to K \pi \nu \), \(\tau \to K^+ \eta \nu\) and $\tau \to K^+ \bar{K^0} \nu\) using only two inputs as the \(\rho\) and \(K^*\) masses, or the two corresponding rms radii, agree with the experimental data. Using the same number of parameters, the corresponding one loop CPTH calculation cannot explain the $\tau$ data.

We argue that dark matter can automatically arise from a gauge theory that possesses a non-minimal left-right gauge symmetry, SU(3)_C \otimes SU(M)_L \otimes SU(N)_R \otimes U(1)_X, for (M,N)=(2,3), (3,2), (3,3), \cdots, and (5,5).

The standard model has postulated the existence of a scalar boson, named the Higgs boson (or the Brout-Englert-Higgs boson, for more complete). This boson plays a central role in a symmetry breaking scheme called the Higgs mechanism making the standard model realistic. However, until recently at least, the 50-year-long-sought Higgs boson had remained the only particle in the standard model not yet discovered experimentally. It is the last but very important missing ingredient of the standard model. Therefore, searching for the Higgs boson is a crucial task and an important mission of particle physics. For this purpose, many theoretical works have been done and dierent experiments have been organized. It may be said in particular that to search for the Higgs boson has been one of the ultimatums of building and running the LHC, the world's largest and most powerful particle accelerator, at CERN, which is a great combination of science and technology. Recently, in the summer of 2012, ATLAS and CMS, the two biggest and general- purpose LHC collaborations, announced the discovery of a new boson with a mass around 125 GeV. Since then, for over two years, ATLAS, CMS and other collaborations have carried out intensive investigations on the newly discovered boson to conrm that this new boson is really the Higgs boson (of the standard model). It is a triumph of science and technology and international cooperation. Here, we will review the main results of these investigations after presenting a brief introduction to the Higgs boson between the theoretical framework of the standard model and Higgs mechanism as well as a theoretical and experimental background of searching for it. This paper may attract interest of not only particle physicists but also a broader audience.

The gold nanoparticles (GNPs) in 15-20 nm size range have attracted attention for fabrication of smart sensing devices in biomedical sciences as diagnostic tools. Citrate capped GNPs are negatively charged, which can be exploited for electrostatic interactions with some positively charged biomolecules like antibody. In this study, we are developing a low-cost technique by using a common microwave system with medium power for synthesizing gold nanoparticles with using sodium citrate (Na\(_{3}\)Ct) reduction in chloroauric acid (HAuCl\(_{4}|).3H\(_{2}\)O). It was found that the comparing with normal thermal method, the reaction by the microwave irradiation was much faster. Besides, effects of the sodium citrate concentration and optical properties of gold nanoparticle swere studied. The optical properties of gold nanoparticles suspension were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-VIS absorption spectroscopy (UV-Vis). Maximum absorbance wavelengths \((\lambda _{max})\) for gold nanoparticles are \(\sim  518-524\) nm with the size of 12-25 nm. The size of gold nanoparticles decreases with increasing concentration of sodium citrate. Besides, the morphology of gold nanoparticles has spherical shape with face-centered-cubic (fcc) crystalline structure.