Leptonic CP Violation and Wolfenstein Parametrization for Lepton Mixing

We investigate a general structure of lepton mixing matrix resulting from the SU$_F$(3) gauge family model with an appropriate vacuum structure of SU$_F$(3) symmetry breaking. It is shown that the lepton mixing matrix can be parametrized by using the Wolfenstein parametrization method to characterize its deviation from the tri-bimaximal mixing. A general analysis for the allowed leptonic CP-violating phase $\delta_e$ and the leptonic Wolfenstein parameters $\lambda_e$, $A_e$, $\rho_e$ is carried out based on the observed lepton mixing angles. We demonstrate how the leptonic CP violation correlates to the leptonic Wolfenstein parameters. It is found that the phase $\delta_e$ is strongly constrained and only a large or nearly maximal leptonic CP-violating phase $|\delta_e| \simeq 3\pi/4 \sim \pi/2$ is favorable when $\lambda_e > 0.15$. In particular, when taking $\lambda_e$ to be the Cabbibo angle \gl_e\simeq \lambda \simeq 0.225, a sensible result for leptonic Wolfenstein parameters and CP violation is obtained with $A_e=1.40$, $\rho_e=0.20$, \delta_{e}\sim 101.76\;^o, which is compatible with the one in quark sector. An interesting correlation between leptons and quarks is observed, which indicates a possible common origin of masses and mixing for the charged-leptons and quarks.Comment: 18 pages, 5 figures, sources of CP-violating phases are clarified, references adde

Utopian fantasy

I design furniture and objects to express my utopian fantasy to people. I hope users can imagine the fantasy through the interaction with my furniture and objects. While people are interacting with my works, they become part of the fantasy. My works are the NPCs (nonplayer characters) of a game created by myself, called Utopian Fantasy. My works are creature-istic, anthropomorphic, and always interactive. They are inspired by nature and everyday life. This series of works I created during my time at RISD express my appreciation for the underwater world and the Internet. My designs beg for interaction and play. Wander around one of my pieces for a couple of seconds, test it, play with it and through interaction my furniture will be happy to share with you everything they know. My furniture’s functional purpose emerges from play, while visually engaging people nearby. I love adding surprises into my pieces, giving them a sense of humor, a point of interaction and exchange. I want people to say, “Oh, how joyful!”, when they interact with my work

SU(3)FSU(3)_{F} Gauge Family Model and New Symmetry Breaking Scale From FCNC Processes

Based on the $SU(3)_{F}$ gauge family symmetry model which was proposed to explain the observed mass and mixing pattern of neutrinos, we investigate the symmetry breaking, the mixing pattern in quark and lepton sectors, and the contribution of the new gauge bosons to some flavour changing neutral currents (FCNC) processes at low energy. With the current data of the mass differences in the neutral pseudo-scalar $P^{0}-\bar{P}^{0}$ systems, we find that the $SU(3)_{F}$ symmetry breaking scale can be as low as 300TeV and the mass of the lightest gauge boson be about $100$TeV. Other FCNC processes, such as the lepton flavour number violation process $\mu^{-}\rightarrow e^{-}e^{+}e^{-}$ and the semi-leptonic rare decay $K\rightarrow \pi \bar{\nu} \nu$, contain contributions via the new gauge bosons exchanging. With the constrains got from $P^0-\bar{P}^0$ system, we estimate that the contribution of the new physics is around $10^{-16}$, far below the current experimental bounds.Comment: 3figure

Holographic Dark Energy Characterized by the Total Comoving Horizon and Insights to Cosmological Constant and Coincidence Problem

The observed acceleration of the present universe is shown to be well explained by the holographic dark energy characterized by the total comoving horizon of the universe ($\eta$HDE). It is of interest to notice that the very large primordial part of the comoving horizon generated by the inflation of early universe makes the $\eta$HDE behave like a cosmological constant. As a consequence, both the fine-tuning problem and the coincidence problem can reasonably be understood with the inflationary universe and holographical principle. We present a systematic analysis and obtain a consistent cosmological constraint on the $\eta$HDE model based on the recent cosmological observations. It is found that the $\eta$HDE model gives the best-fit result $\Omega_{m0}=0.270$ ($\Omega_{de0}=0.730$) and the minimal $\chi^2_{min}=542.915$ which is compatible with $\chi^2_{\Lambda {\rm CDM}}=542.919$ for the $\Lambda$CDM model.Comment: 17 pages, 4 figures, two eqs. (26)(27) added for the consistent approximate solution of dark energy in early universe, references added, published version in PR

Development of Terahertz Quantum Well Photodetector at 3 THz

This thesis reports a new terahertz (=3.22 THz) quantum well photodetector (THz QWP) as well as comprehensive numerical models simulating device active region and different grating couplers including traditional diffraction metal grating and novel patch antenna structure. Among all the terahertz detectors, terahertz quantum well photodetector (THz QWP), has proved its fast optical response speed and remarkable sensitivity and shown great potential for applications in security, bio-medical technology and space communication. However, due to high requirements in experiment condition and growth quality, THz QWPs absorbed at 3 THz or lower have not been much developed yet. Furthermore, THz QWP working around 3 THz can be combined with one of the strongest terahertz emitters, terahertz quantum cascade laser (THz QCL), for ultrafast spectroscopy and imaging applications. Recently, THz QWPs integrated with different grating couplers have been explored and are now intensively investigated to improve device temperature performance. In that regard, we aim to improve the simulation model and develop a new THz QWP absorbing at 3 THz. Moreover, numerical COMSOL models are built to analyze optical properties of traditional diffraction metal grating coupler and novel patch antenna coupler in this work. According to measured current density-voltage (j-V) profiles and absorption spectrum, the proposed THz QWP with a new active region design has its background-limited infrared performance (BLIP) temperature at 10 K and manages to achieve terahertz range absorption at lower frequency around 3 THz. Results show a peak responsivity of 1.9 A/W, a peak detectivity of 4.63×1010 cmHz1/2/W and an absorption range from 94.5 cm-1 (2.83 THz) to 142.7 cm-1 (4.25 THz). To our knowledge, this THz QWP has the lowest peak absorption frequency (3.22 THz) and it is the second one that works near 3 THz. Measured j-V profiles show a size-dependent shifting, indicating the existence of sidewall leakage currents, and the comparison between simulation and measurement results of j-V profiles reveals the consistency, especially at higher temperature. In addition, simulation results on 1D metal grating coupler and patch antenna coupler are demonstrated and they strongly agree with the experiment data from literatures as well as general rules of thumb

Timing and Congestion Driven Algorithms for FPGA Placement

Placement is one of the most important steps in physical design for VLSI circuits. For field programmable gate arrays (FPGAs), the placement step determines the location of each logic block. I present novel timing and congestion driven placement algorithms for FPGAs with minimal runtime overhead. By predicting the post-routing timing-critical edges and estimating congestion accurately, this algorithm is able to simultaneously reduce the critical path delay and the minimum number of routing tracks. The core of the algorithm consists of a criticality-history record of connection edges and a congestion map. This approach is applied to the 20 largest Microelectronics Center of North Carolina (MCNC) benchmark circuits. Experimental results show that compared with the state-of-the-art FPGA place and route package, the Versatile Place and Route (VPR) suite, this algorithm yields an average of 8.1% reduction (maximum 30.5%) in the critical path delay and 5% reduction in channel width. Meanwhile, the average runtime of the algorithm is only 2.3X as of VPR

Bioimaging with photonic crystal enhanced microscopy

The work presented in this dissertation addresses the optimization and application of a newly developed imaging modality, named photonic crystal enhanced microscopy (PCEM) for label-free detection of the surface attached biological samples. Photonic crystal, supporting guided-mode resonances and providing local optical modes, can enhance the light-matter interaction on its surface and thus used for label-free detection and biosensing. One dimensional photonic crystal surfaces are designed and utilized as a biosensor, and further integrated with an ordinary bright-field microscope. To demonstrate the validity of the photonic crystal biosensor, a three-dimensional modeling is developed and evaluated with finite-difference time-domain (FDTD) algorithm to predict and visualize the electromagnetic field redistribution upon the device surface. Applications of the photonic crystal enhanced microscopy are carried out for live cell imaging, nanoparticle detection and protein-protein binding detection. First, labelfree detection for live cell with PCEM imaging system is performed. Three different cellular phenomena are involved in this study, including cell adhesion, cell migration and stem cell differentiation. A novel imaging analysis software is developed to dynamically track the cell plasma membrane evolution. This traction software reveals mass redistribution with high resolution during cell migration which is previously difficult to evaluate quantitatively. Furthermore, both dielectric and metallic nanoparticles are examined and proved to be detectable as label-free detection using PCEM imaging system. Another novel imaging analysis software is developed to automatically count the number of nanoparticles attached on the sensor surface within the imaging field of view. Finally, a newly developed detection modality for protein-protein binding is demonstrated through PCEM imaging system using nanoparticle as tags. This new detection modality can avoid the photobleach problem and may also hold the potential to detect ultra-low concentrations of protein in the future. In summary, photonic crystal biosensor and its associated imaging system with microscopy developed in this work show great promise to the label-free biosensing and bioimaging. Future work will extend the application of PCEM to broader research and application fields served as the next generation sensing modalities