Recent results from NA48

Recent results from the experiments NA48, NA48/1 and NA48/2 are presented, including: direct CP-violation and Dalitz plot slopes measurements for K+- --> 3 pi decays; pi pi scattering effects in K+- --> pi+- pi0 pi0 and Ke4 decays, as well as Ke4 form factors and branching fraction; measurements on radiative charged kaons and hyperon decays, semileptonic decays of neutral and charged kaons; KL --> pi+ pi- branching ratio and |eta+-| measurement; lepton universality check with Kl2 decays.Comment: Talk given at 21th Rencontres de Physique de La Vallee d'Aoste, La Thuile, Aosta Valley, Italy, 4-10 Mar 200

Search for direct CP-violation in K+- --> 3pi decays by NA48/2

A high precision search for direct CP-violation in K+- --> 3 pi decays was performed by the NA48/2 experiment at CERN SPS. The asymmetry in the Dalitz plot linear slopes A_g = (g^+ - g^-)/(g^+ + g^-) is measured to be A^c_g = (-1.3 +- 2.3)x10^-4 by studying ~3.1x10^9 K+- --> pi+- pi+ pi- decays and A^n_g = (2.1 +- 1.9)x10^-4 by studying ~91x10^6 K+- --> pi+- pi0 pi0 decays. The unique double- beam system, the design of the detectors and the method of analysis provide good control of the instrumental charge asymmetries and allow to keep the precision of the result limited by statistics, reaching accuracy one order of magnitude better than in previous experiments.Comment: Talk given at XXXIII International Conference on High Energy Physics (ICHEP'06), Moscow, Russia, July 26 - August 2, 200

Lepton universality test with Kl2 decays at NA62 experiment

The experiment NA62 at CERN collected a large sample of K+- leptonic decays in order to perform precise test of lepton universality, by measuring the helicity suppressed ratio R_K=Gamma(K+- --> e+- nu)/Gamma(K+- --> mu+- nu). The preliminary result of the analysis based on 51089 K+ --> e+nu candidates is R_K=(2.500+-0.016)x10^{-5}, consistent with the predictions of the Standard Model.Comment: Lake Louise Winter Institute 2010 proceeding

Hot carriers in a bipolar graphene

Hot carriers in a doped graphene under dc electric field is described taking into account the intraband energy relaxation due to acoustic phonon scattering and the interband generation-recombination transitions caused by thermal radiation. The consideration is performed for the case when the intercarrier scattering effectively establishes the quasiequilibrium electron-hole distributions, with effective temperature and concentrations of carriers. The concentration and energy balance equations are solved taking into account an interplay between weak energy relaxation and generation-recombination processes. The nonlinear conductivity is calculated for the momentum relaxation caused by the elastic scattering. The current-voltage characteristics, and the transition between bipolar and monopolar regimes of conductivity are obtained and analyzed, for different temperatures and gate voltages.Comment: Copyright (2010) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article has been accepted by Journal of Applied Physics. After it is published, it will be found at http://jap.aip.org/japiau/10