Rare decays Bs→l+l−B_s\to l^+l^- and B→Kl+l−B\to Kl^+l^- in \the topcolor-assisted technicolor model

We examine the rare decays $B_s\to l^+l^-$ and $B\to Kl^+l^-$ in the framework of the topcolor-assisted technicolor ($TC2$) model. The contributions of the new particles predicted by this model to these rare decay processes are evaluated. We find that the values of their branching ratios are larger than the standard model predictions by one order of magnitude in wide range of the parameter space. The longitudinal polarization asymmetry of leptons in $B_s \to l^+l^-$ can approach \ord(10^{-2}). The forward-backward asymmetry of leptons in $B \to Kl^+l^-$ is not large enough to be measured in future experiments. We also give some discussions about the branching ratios and the asymmetry observables related to these rare decay processes in the littlest Higgs model with T-parity.Comment: 29 pages, 9 figure, corrected typos, the version to appear in PR

Refinement and growth enhancement of Al2Cu phase during magnetic field assisting directional solidification of hypereutectic Al-Cu alloy.

International audienceUnderstanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites. In this study, a hypereutectic Al-40 wt.% Cu alloy has been directionally solidified under various axial magnetic fields and the morphology of Al2Cu phase was quantified in 3D by means of high resolution synchrotron X-ray tomography. With rising magnetic fields, both increase of Al2Cu phase's total volume and decrease of each column's transverse section area were found. These results respectively indicate the growth enhancement and refinement of the primary Al2Cu phase in the magnetic field assisting directional solidification. The thermoelectric magnetic forces (TEMF) causing torque and dislocation multiplication in the faceted primary phases were thought dedicate to respectively the refinement and growth enhancement. To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope

Research Program towards Observation of Neutrino-Nucleus Coherent Scattering

The article describes the research program pursued by the TEXONO Collaboration towards an experiment to observe coherent scattering between neutrinos and the nucleus at the power reactor. The motivations of studying this process are surveyed. In particular, a threshold of 100-200 eV has been achieved with an ultra-low-energy germanium detector prototype. This detection capability at low energy can also be adapted to conduct searches of Cold Dark Matter in the low-mass region as well as to enhance the sensitivities in the study of neutrino magnetic moments.Comment: 5 pages, 8 figures ; Proceedings of TAUP-2005 Workshop, Spain, 2005. Updated on 2006/9/15 for Proceedings of Neutrino-2006 Conference, Santa Fe, 200

Design and performance analysis of network code division multiplexing for wireless sensor networks

© 2015 IEEE. In this paper, we investigate the performance of a wireless sensor network, in which multiple groups of source nodes communicate with their respective destination nodes with the help of a common relay network. A network code division multiplexing (NCDM) scheme is proposed to remove the inter-session interference among multiple transmission sessions at each destination. We focus on analyzing the soft processing algorithm of the NCDM scheme. Based on the analysis results, a new code design criteria for the construction of the generator matrix is proposed. Simulation results show that by following the proposed code design criteria, the bit error ratio (BER) performance gap between the scheme we studied and the serial session scheme can be managed effectively. In serial session scheme, source nodes in a number of groups communicate with their respective destinations in a time division manner

Stabilization of systems with probabilistic interval input delays and its applications to networked control systems

Motivated by the study of a class of networked control systems, this correspondence paper is concerned with the design problem of stabilization controllers for linear systems with stochastic input delays. Different from the common assumptions on time delays, it is assumed here that the probability distribution of the delay taking values in some intervals is known a priori. By making full use of the information concerning the probability distribution of the delays, criteria for the stochastic stability and stabilization controller design are derived. Traditionally, in the case that the variation range of the time delay is available, the maximum allowable bound of time delays can be calculated to ensure the stability of the time-delay system. It is shown, via numerical examples, that such a maximum allowable bound could be made larger in the case that the probability distribution of the time delay is known. © 2009 IEEE.published_or_final_versio

Charmless decays B->pipi, piK and KK in broken SU(3)symmetry

Charmless B decay modes $B \to \pi \pi, \pi K$ and $KK$ aresystematically investigated with and without flavor SU(3) symmetry. Independent analyses on $\pi \pi$ and $\pi K$ modes both favor a large ratio between color-suppressed tree ($C$) and tree ($T)$ diagram, which suggests that they are more likely to originate from long distance effects. The sizes of QCD penguin diagrams extracted individually from $\pi\pi$, $\pi K$ and $KK$ modes are found to follow a pattern of SU(3) breaking in agreement with the naive factorization estimates. Global fits to these modes are done under various scenarios of SU(3)relations. The results show good determinations of weak phase $\gamma$ in consistency with the Standard Model (SM), but a large electro-weak penguin (P_{\tmop{EW}}) relative to $T + C$ with a large relative strong phase are favored, which requires an big enhancement of color suppressed electro-weak penguin (P_{\tmop{EW}}^C) compatible in size but destructively interfering with P_{\tmop{EW}} within the SM, or implies new physics. Possibility of sizable contributions from nonfactorizable diagrams such as $W$-exchange ($E$), annihilation($A$) and penguin-annihilation diagrams($P_A$) are investigated. The implications to the branching ratios and CP violations in $K K$modes are discussed.Comment: 27 pages, 9 figures, reference added, to appear in Phy.Rev.

New Results on Transceiver Design for Two-Hop Amplify-and-Forward MIMO Relay Systems With Direct Link

© 2016 IEEE. Conventional amplify-and-forward (AF) protocol for half-duplex two-hop multiple-input-multiple-output (MIMO) relay systems assumes that the source node transmits the signal only at the first time slot. While making the source node silent at the second time slot simplifies the system design, it is strictly suboptimal. To improve the system performance, in this paper, we consider that the source node transmits signals during both time slots. We develop two novel iterative algorithms to optimize the source, relay, and receiver matrices in this new AF MIMO relay system. Both algorithms are based on the minimum mean-square error (MMSE) criterion. In particular, the first algorithm is applicable for general MIMO relay systems with multiple concurrent data streams, where the source, relay, and receiver matrices are optimized in an alternating fashion until convergence. The second algorithm is developed for MIMO relay systems with a single data stream, where the source precoding vectors and the relay precoding matrix are optimized iteratively and the receiver matrix is obtained after the convergence of the source vectors and the relay matrix. Simulation results show that compared with conventional AF MIMO relay systems, the proposed system provides better bit-error-rate performance for both multiple-data-stream and single-data-stream cases