Validity of approximations applied in calculations of single-wall metallic carbon nanotube current-voltage characteristics

The calculation results of dependencies of electric current in the infinitely long single-wall metallic carbon nanotubes of armchair type with different diameter values on the strength of constant and uniform longitudinal electric field applied to them are presented in this study. On the one hand the results have been obtained by an accurate numerical self-consistent tight-binding full-band solution of the Boltzmann transport equations for electrons and phonons in the electric quantum limit. On the other hand the results have been obtained by solution of these equations after application of a number of commonly used simplifications and approximations. It is ascertained that the approximately calculated dependencies considerably diverge from the rigorously calculated ones. In addition the relaxation time of non-equilibrium phonons in the single-wall metallic carbon nanotubes has been estimated by means of comparison of the calculation results with the well-known experimental data. Its value is equal to 2.2+/-0.1 ps.Comment: 10 pages, 4 figure

Fermionic decays of SM Higgs

In this document I present an overview of the recent results published by ATLAS and CMS collaborations on the searches for SM Higgs boson decay to fermions. The document summarizes the status of the analyses up to September of 2014 and contains the results of pp collision Data at $\sqrt{s} =$7 and 8 TeV. Searches for $H\to\tau\tau$, $H\to bb$, $H\to\mu\mu$ and $ttH$ processes are presented.Comment: XXXIV Physics in Collision Symposiu

Non-thermal photon production via bulk comptonization at supernova shock breakout

We investigate roles of the bulk comptonization process in the propagation of thermal photons emitted at the shock breakout of a supernova explosion. We use a hydrodynamical model based on a self-similar solution for the shock breakout. The propagation of photons is treated by a Monte-Carlo technique. Results of the simulations successfully reproduce the power-law spectrum observed by X-ray observations for XRF 080109/SN 2008D, if a mildly relativistic shock velocity is assumed. Effects of some radiative processes, photoionization, radiative recombination, and free-free absorption on the propagation of emitted photons are also investigated. It is found that none of them hardly changes the spectrum regarding the progenitor stars of type Ib or Ic supernovae. Light curves calculated under the assumption of a spherical explosion indicate that the progenitor radius is required to be $/sim 10^{13}$ cm.Comment: 10pages, 6 figures, to appear in Ap

Asymptotics of a Clustering Criterion for Smooth Distributions

We develop a clustering framework for observations from a population with a smooth probability distribution function and derive its asymptotic properties. A clustering criterion based on a linear combination of order statistics is proposed. The asymptotic behavior of the point at which the observations are split into two clusters is examined. The results obtained can then be utilized to construct an interval estimate of the point which splits the data and develop tests for bimodality and presence of clusters