A Critical Examination to the Unitarized ππ\pi\pi Scattering Chiral Amplitudes

We discuss the Pad\'e approximation to the $\pi\pi$ scattering amplitudes in 1--loop chiral perturbation theory. The approximation restores unitarity and can reproduce the correct resonance poles, but the approximation violates crossing symmetry and produce spurious poles on the complex $s$ plane and therefore plagues its predictions on physical quantities at quantitative level. However we find that one virtual state in the IJ=20 channel may have physical relevance.Comment: 13 pages + 4 eps figures submit to Commun. Theor. Phy

Entropy-based implied volatility and its information content

This paper investigates the maximum entropy approach on estimating implied volatility. The entropy approach also allows to measure option implied skewness and kurtosis nonparametrically, and to construct confidence intervals. Simulations show that the en- tropy approach outperforms the Black-Scholes model and model-free method in backing out implied volatility, when the risk neutral distribution of the underlying asset deviates from log-normal distribution, and when the number of available options is limited. Using S&P500 index options, we apply the entropy method to obtain implied volatilities and their confidence intervals. We find that the entropy-based implied volatility subsumes all information in the Black-Scholes implied volatility and historical volatility. In addition, it has more predictive power than the model-free i

Micro-relief analysis with skin capacitive imaging

© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Background: In this study, the performance of capacitive imagining in skin micro-relief analysis was investigated. This measurement principle has been used for skin hydration measurements over the last decade and it is commercially available by various manufacturers. Strengthening its potential for new applications could offer an affordable and portable multi-purpose device for in vivo skin research. Previous studies in the literature have used a wide range of optical devices to determine how the skin surface topographic features are affected by chronological age, environmental influences and living habits. Material and methods: A capacitive system was used in order to capture hydration images from the middle volar forearm of twelve volunteers. The visual output of the system was studied and image processing algorithms were adapted to automatically extract skin micro-relief features. The change in the skin network of lines during arm extension, the lines’ anisotropy index and the number of closed polygons per skin surface area were plotted against the subjects’ chronological age. The results were compared with optical measurements from the literature to validate our algorithms and evaluate the capacitive imaging in skin micro-relief analysis. Results: The change in the intensity of primary and secondary lines during arm extension and the number of closed polygons per surface area were in agreement with the literature. The anisotropy index output gave inconclusive results. Conclusions: The experimental results show that the capacitive systems could only extract two-dimensional skin topographic features. This is the peer reviewed version of the following article:Bontozoglou, C., Zhang, X., and Xiao, P. (2019). Micro-relief analysis with skin capacitive imaging. Skin Research and Technology, 25(2), 165-170. which has been published in final form at https://www.doi.org/10.1111/srt.12628 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions

A new class of (2+1)(2+1)-d topological superconductor with Z8\mathbb{Z}_8 topological classification

The classification of topological states of matter depends on spatial dimension and symmetry class. For non-interacting topological insulators and superconductors the topological classification is obtained systematically and nontrivial topological insulators are classified by either integer or $Z_2$. The classification of interacting topological states of matter is much more complicated and only special cases are understood. In this paper we study a new class of topological superconductors in $(2+1)$ dimensions which has time-reversal symmetry and a $\mathbb{Z}_2$ spin conservation symmetry. We demonstrate that the superconductors in this class is classified by $\mathbb{Z}_8$ when electron interaction is considered, while the classification is $\mathbb{Z}$ without interaction.Comment: 5 pages main text and 3 pages appendix. 1 figur

Excitation of nonlinear ion acoustic waves in CH plasmas

Excitation of nonlinear ion acoustic wave (IAW) by an external electric field is demonstrated by Vlasov simulation. The frequency calculated by the dispersion relation with no damping is verified much closer to the resonance frequency of the small-amplitude nonlinear IAW than that calculated by the linear dispersion relation. When the wave number $k\lambda_{De}$ increases, the linear Landau damping of the fast mode (its phase velocity is greater than any ion's thermal velocity) increases obviously in the region of $T_i/T_e < 0.2$ in which the fast mode is weakly damped mode. As a result, the deviation between the frequency calculated by the linear dispersion relation and that by the dispersion relation with no damping becomes larger with $k\lambda_{De}$ increasing. When $k\lambda_{De}$ is not large, such as $k\lambda_{De}=0.1, 0.3, 0.5$, the nonlinear IAW can be excited by the driver with the linear frequency of the modes. However, when $k\lambda_{De}$ is large, such as $k\lambda_{De}=0.7$, the linear frequency can not be applied to exciting the nonlinear IAW, while the frequency calculated by the dispersion relation with no damping can be applied to exciting the nonlinear IAW.Comment: 10 pages, 9 figures, Accepted by POP, Publication in August 1

Rotating system for four-dimensional transverse rms-emittance measurements

Knowledge of the transverse four-dimensional beam rms-parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Of special interest is the removal of inter-plane correlations to reduce the projected emittances. A dedicated ROtating System for Emittance measurements (ROSE) has been proposed, developed, and successfully commissioned to fully determine the four-dimensional beam matrix. This device has been used at the High Charge injector (HLI) at GSI using a beam line which is composed of a skew quadrupole triplet, a normal quadrupole doublet, and ROSE. Mathematical algorithms, measurements, and results for ion beams of 83Kr13+ at 1.4 MeV/u are reported in this paper.Comment: 11 pages, 10 figure