Experimental tests on the lifetime Asymmetry

The experimental test problem of the left-right polarization-dependent lifetime asymmetry is discussed. It shows that the existing experiments cannot demonstrate the lifetime asymmetry to be right or wrong after analyzing the measurements on the neutron, the muon and the tau lifetime, as well as the $g-2$ experiment. However, It is pointed out emphatically that the SLD and the E158 experiments, the measurements of the left-right integrated cross section asymmetry in $Z$ boson production by $e^+e^-$ collisions and by electron-electron M{\o}ller scattering, can indirectly demonstrate the lifetime asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose some possible experiments on the decays of polarized muons. The precise measurement of the lifetime asymmetry could have important significance for building a muon collider, also in cosmology and astrophysics. It would provide a sensitive test of the standard model in particle physics and allow for exploration of the possible $V+A$ interactions.Comment: 11 pages, 1 figur

Reversible Embedding to Covers Full of Boundaries

In reversible data embedding, to avoid overflow and underflow problem, before data embedding, boundary pixels are recorded as side information, which may be losslessly compressed. The existing algorithms often assume that a natural image has little boundary pixels so that the size of side information is small. Accordingly, a relatively high pure payload could be achieved. However, there actually may exist a lot of boundary pixels in a natural image, implying that, the size of side information could be very large. Therefore, when to directly use the existing algorithms, the pure embedding capacity may be not sufficient. In order to address this problem, in this paper, we present a new and efficient framework to reversible data embedding in images that have lots of boundary pixels. The core idea is to losslessly preprocess boundary pixels so that it can significantly reduce the side information. Experimental results have shown the superiority and applicability of our work

Intense beam of metastable Muonium

Precision spectroscopy of the Muonium Lamb shift and fine structure requires a robust source of 2S Muonium. To date, the beam-foil technique is the only demonstrated method for creating such a beam in vacuum. Previous experiments using this technique were statistics limited, and new measurements would benefit tremendously from the efficient 2S production at a low energy muon ($<20$ keV) facility. Such a source of abundant low energy $\mathrm{\mu^+}$ has only become available in recent years, e.g. at the Low-Energy Muon beamline at the Paul Scherrer Institute. Using this source, we report on the successful creation of an intense, directed beam of metastable Muonium. We find that even though the theoretical Muonium fraction is maximal in the low energy range of $2-5$ keV, scattering by the foil and transport characteristics of the beamline favor slightly higher $\mathrm{\mu^+}$ energies of $7-10$ keV. We estimate that an event detection rate of a few events per second for a future Lamb shift measurement is feasible, enabling an increase in precision by two orders of magnitude over previous determinations

Temperature dependence of electron-spin relaxation in a single InAs quantum dot at zero applied magnetic field

The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot (QD) was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show that the electron-spin relaxation is clearly divided into two different temperature regimes: (i) T < 50 K, spin relaxation depends on the dynamical nuclear spin polarization (DNSP) and is approximately temperature-independent, as predicted by Merkulov et al. (ii) T > about 50 K, spin relaxation speeds up with increasing temperature. A model of two LO phonon scattering process coupled with hyperfine interaction is proposed to account for the accelerated electron spin relaxation at higher temperatures.Comment: 10 pages, 4 figure

Massive MIMO for Full-Duplex Cellular Two-Way Relay Network: A Spectral Efficiency Study

© 2017 IEEE. This paper presents the new analysis of the applications of massive multiple-input-multiple-output (MIMO) in full-duplex (FD) cellular two-way relay networks, and sheds valuable insights on the interactions between massive MIMO, and relay and duplex modes. Practical scenarios are considered, where massive MIMO is deployed at the base station and the relay station. Based on generic relay modes, namely, antenna-selection-based decode-and-forward (DF) relay and signal-space alignment based amplify-and-forward (AF) relay, closed-form expressions for the asymptotic signal-to-interference-plus-noise ratios (SINRs) are derived. The difference between AF and DF in the FD mode is quantified, and so is that between FD and half-duplex (HD) under the two relay modes. With massive MIMO, the superiority of DF in the FD mode is confirmed in terms of spectral efficiency. The sufficient conditions for the FD mode to outperform the HD mode are identified. The effectiveness of massive MIMO in terms of self-loop interference cancellation and inter-user interference suppression is proved. All these insightful findings are corroborated by simulations

On resonant scatterers as a factor limiting carrier mobility in graphene

We show that graphene deposited on a substrate has a non-negligible density of atomic scale defects. This is evidenced by a previously unnoticed D peak in the Raman spectra with intensity of about 1% with respect to the G peak. We evaluated the effect of such impurities on electron transport by mimicking them with hydrogen adsorbates and measuring the induced changes in both mobility and Raman intensity. If the intervalley scatterers responsible for the D peak are monovalent, their concentration is sufficient to account for the limited mobilities achievable in graphene on a substrate.Comment: version 2: several comments are taken into account and refs adde

Acceleration disturbances and requirements for ASTROD I

ASTRODynamical Space Test of Relativity using Optical Devices I (ASTROD I) mainly aims at testing relativistic gravity and measuring the solar-system parameters with high precision, by carrying out laser ranging between a spacecraft in a solar orbit and ground stations. In order to achieve these goals, the magnitude of the total acceleration disturbance of the proof mass has to be less than 10&#8722;13 m s&#8722;2 Hz&#8722;1/2 at 0.1 m Hz. In this paper, we give a preliminary overview of the sources and magnitude of acceleration disturbances that could arise in the ASTROD I proof mass. Based on the estimates of the acceleration disturbances and by assuming a simple controlloop model, we infer requirements for ASTROD I. Our estimates show that most of the requirements for ASTROD I can be relaxed in comparison with Laser Interferometer Space Antenna (LISA).Comment: 19 pages, two figures, accepted for publication by Class. Quantum Grav. (at press