EVM and Achievable Data Rate Analysis of Clipped OFDM Signals in Visible Light Communication

Orthogonal frequency division multiplexing (OFDM) has been considered for visible light communication (VLC) thanks to its ability to boost data rates as well as its robustness against frequency-selective fading channels. A major disadvantage of OFDM is the large dynamic range of its time-domain waveforms, making OFDM vulnerable to nonlinearity of light emitting diodes (LEDs). DC biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM) are two popular OFDM techniques developed for the VLC. In this paper, we will analyze the performance of the DCO-OFDM and ACO-OFDM signals in terms of error vector magnitude (EVM), signal-to-distortion ratio (SDR), and achievable data rates under both average optical power and dynamic optical power constraints. EVM is a commonly used metric to characterize distortions. We will describe an approach to numerically calculate the EVM for DCO-OFDM and ACO-OFDM. We will derive the optimum biasing ratio in the sense of minimizing EVM for DCO-OFDM. Additionally, we will formulate the EVM minimization problem as a convex linear optimization problem and obtain an EVM lower bound against which to compare the DCO-OFDM and ACO-OFDM techniques. We will prove that the ACO-OFDM can achieve the lower bound. Average optical power and dynamic optical power are two main constraints in VLC. We will derive the achievable data rates under these two constraints for both additive white Gaussian noise (AWGN) channel and frequency-selective channel. We will compare the performance of DCO-OFDM and ACO-OFDM under different power constraint scenarios

Muon Anomalous g−2g -2 and Gauged Lμ−LτL_\mu - L_\tau Models

In this paper we study $Z'$ contribution to $g -2$ of the muon anomalous magnetic dipole moment in gauged $U(1)_{L_\mu - L_\tau}$ models. Here $L_i$ are the lepton numbers. We find that there are three classes of models which can produce a large value of $g-2$ to account for possible discrepancy between the experimental data and the Standard Model prediction. The three classes are: a) Models with an exact $U(1)_{L_\mu - L_\tau}$. In these models, $Z'$ is massless. The new gauge interaction coupling $e a/\cos\theta_W$ is constrained to be $0.8\times 10^{-3} < |a| < 2.24\times 10^{-3}$. b) Models with broken $U(1)_{L_\mu - L_\tau}$ and the breaking scale is not related to electroweak symmetry breaking scale. The $Z'$ gauge boson is massive. The allowed range of the coupling and the $Z'$ mass are constrained, but $Z'$ mass can be large; And c) The $U(1)_{L_\mu-L_\tau}$ is broken and the breaking scale is related to the electroweak scale. In this case the $Z'$ mass is constrained to be $\sim 1.2$ GeV. We find that there are interesting experimental signatures in $\mu^+\mu^-\to \mu^+\mu^-, \tau^+\tau^-$ in these models.Comment: 13 pages, 9 figure

Nearly Bi-Maximal Neutrino Mixing, Muon g-2 Anomaly and Lepton-Flavor-Violating Processes

We interpret the newly observed muon g-2 anomaly in the framework of a leptonic Higgs doublet model with nearly degenerate neutrino masses and nearly bi-maximal neutrino mixing. Useful constraints are obtained on the rates of lepton-flavor-violating rare decays $\tau \to \mu \gamma$, $\mu \to e \gamma$ and $\tau \to e \gamma$ as well as the $\mu$-$e$ conversion ratio $R_{\mu e}$. We find that $\Gamma (\mu \to e \gamma)$, $\Gamma (\tau \to e \gamma)$ and $R_{\mu e}$ depend crucially on possible non-zero but samll values of the neutrino mixing matrix element $V_{e3}$, and they are also sensitive to the Dirac-type CP-violating phase. In particular, we show that $\Gamma (\tau \to \mu \gamma)/m^5_\tau$, $\Gamma (\mu \to e \gamma)/m^5_\mu$ and $\Gamma (\tau \to e \gamma)/m^5_\tau$ are approximately in the ratio $1: 2|V_{e3}|^2: 2|V_{e3}|^2$ if $|V_{e3}|$ is much larger than ${\cal O}(10^{-2})$, and in the ratio $2 (\Delta m^2_{\rm atm})^2: (\Delta m^2_{\rm sun})^2:(\Delta m^2_{\rm sun})^2$ if $|V_{e3}|$ is much lower than ${\cal O}(10^{-3})$, where $\Delta m^2_{\rm atm}$ and $\Delta m^2_{\rm sun}$ are the corresponding mass-squared differences of atmospheric and solar neutrino oscillations.Comment: LaTex 6 pages (2 PS figures). Phys. Rev. D (in printing

Bottom-Tau Unification in SUSY SU(5) GUT and Constraints from b to s gamma and Muon g-2

An analysis is made on bottom-tau Yukawa unification in supersymmetric (SUSY) SU(5) grand unified theory (GUT) in the framework of minimal supergravity, in which the parameter space is restricted by some experimental constraints including Br(b to s gamma) and muon g-2. The bottom-tau unification can be accommodated to the measured branching ratio Br(b to s gamma) if superparticle masses are relatively heavy and higgsino mass parameter \mu is negative. On the other hand, if we take the latest muon g-2 data to require positive SUSY contributions, then wrong-sign threshold corrections at SUSY scale upset the Yukawa unification with more than 20 percent discrepancy. It has to be compensated by superheavy threshold corrections around the GUT scale, which constrains models of flavor in SUSY GUT. A pattern of the superparticle masses preferred by the three requirements is also commented.Comment: 21pages, 6figure

The anomalous magnetic moment of the muon and radiative lepton decays

The leptons are viewed as composite objects, exhibiting anomalous magnetic moments and anomalous flavor-changing transition moments. The decay $\mu \to e \gamma$ is expected to occur with a branching ratio of the same order as the present experimental limit.Comment: 5 page

Deconstructing Gaugino Mediation

We present a model of supersymmetry breaking which produces gaugino masses and negligible scalar masses at a high scale. The model is inspired by ``deconstructing'' or ``latticizing'' models in extra dimensions where supersymmetry breaking and visible matter are spatially separated. We find a simple four-dimensional model which only requires two lattice sites (or gauge groups) to reproduce the phenomenology.Comment: LaTeX, 9 pages, acknowledgements adde

Muon anomalous magnetic moment in string inspired extended family models

We propose a standard model minimal extension with two lepton weak SU(2) doublets and a scalar singlet to explain the deviation of the measured anomalous magnetic moment of the muon from the standard model expectation. This scheme can be naturally motivated in string inspired models such as E_6 and AdS/CFT.Comment: 9 pages, RevTeX, 2 figures, version to be published in Phys. Rev.

The Reach of the Fermilab Tevatron and CERN LHC for Gaugino Mediated SUSY Breaking Models

In supersymmetric models with gaugino mediated SUSY breaking (inoMSB), it is assumed that SUSY breaking on a hidden brane is communicated to the visible brane via gauge superfields which propagate in the bulk. This leads to GUT models where the common gaugino mass $m_{1/2}$ is the only soft SUSY breaking term to receive contributions at tree level. To obtain a viable phenomenology, it is assumed that the gaugino mass is induced at some scale $M_c$ beyond the GUT scale, and that additional renormalization group running takes place between $M_c$ and $M_{GUT}$ as in a SUSY GUT. We assume an SU(5) SUSY GUT above the GUT scale, and compute the SUSY particle spectrum expected in models with inoMSB. We use the Monte Carlo program ISAJET to simulate signals within the inoMSB model, and compute the SUSY reach including cuts and triggers approriate to Fermilab Tevatron and CERN LHC experiments. We find no reach for SUSY by the Tevatron collider in the trilepton channel. %either with or without %identified tau leptons. At the CERN LHC, values of $m_{1/2}=1000$ (1160) GeV can be probed with 10 (100) fb$^{-1}$ of integrated luminosity, corresponding to a reach in terms of $m_{\tg}$ of 2150 (2500) GeV. The inoMSB model and mSUGRA can likely only be differentiated at a linear $e^+e^-$ collider with sufficient energy to produce sleptons and charginos.Comment: 17 page revtex file with 9 PS figure

Bi-large Neutrino Mixing and Mass of the Lightest Neutrino from Third Generation Dominance in a Democratic Approach

We show that both small mixing in the quark sector and large mixing in the lepton sector can be obtained from a simple assumption of universality of Yukawa couplings and the right-handed neutrino Majorana mass matrix in leading order. We discuss conditions under which bi-large mixing in the lepton sector is achieved with a minimal amount of fine-tuning requirements for possible models. From knowledge of the solar and atmospheric mixing angles we determine the allowed values of sin \theta_{13}. If embedded into grand unified theories, the third generation Yukawa coupling unification is a generic feature while masses of the first two generations of charged fermions depend on small perturbations. In the neutrino sector, the heavier two neutrinos are model dependent, while the mass of the lightest neutrino in this approach does not depend on perturbations in the leading order. The right-handed neutrino mass scale can be identified with the GUT scale in which case the mass of the lightest neutrino is given as (m_{top}^2/M_{GUT}) sin^2 \theta_{23} sin^2 \theta_{12} in the limit sin \theta_{13} = 0. Discussing symmetries we make a connection with hierarchical models and show that the basis independent characteristic of this scenario is a strong dominance of the third generation right-handed neutrino, M_1, M_2 < 10^{-4} M_3, M_3 = M_{GUT}.Comment: typos correcte