Microtorus: a High Finesse Microcavity with Whispering-Gallery Modes

We have demonstrated a 165 micron oblate spheroidal microcavity with free spectral range 383.7 GHz (3.06nm), resonance bandwidth 25 MHz (Q ~ 10^7) at 1550nm, and finesse F > 10^4. The highly oblate spheroidal dielectric microcavity combines very high Q-factor, typical of microspheres, with vastly reduced number of excited whispering-gallery (WG) modes (by two orders of magnitude). The very large free spectral range in the novel microcavity - few hundred instead of few GigaHertz in typical microspheres - is desirable for applications in spectral analysis, narrow-linewidth optical and RF oscillators, and cavity QED.Comment: 11 pages, 3 figure

Sub-Terahertz Low Power UWB Communication Link for WPAN

proposed is  ultra-wideband (UWB) wireless communication system for transmitting digital information in the terahertz frequency range on the basis of analog  noise carrier with a low level of radiation. The digital information at the transmitter is inserted using code spectrum modulation of noise signal. The bit error rate (BER) performance is analyzed for different signal to noise ratios at the receiver at different bit rates. The proposed UWB wireless communication system is characterized by high noise immunity and the ability to secure transmission of information "in the noise" for the received information signal below the noise level. The designed UWB sub-terahertz communication link at 70 microwatt transmit power is suitable for wireless personal area networks. Keywords: ultra-wide band UWB, WPAN, code spectrum modulation

Optical Sensors Based on Whispering Gallery Modes in Fluorescent Microbeads: Response to Specific Interactions

Whispering gallery modes (WGMs) in surface-fixated fluorescent polystyrene microbeads are studied in view of their capability of sensing the formation of biochemical adsorption layers on their outer surface with the well-established biotin-streptavidin specific binding as the model system. Three different methods for analysis of the observed shifts in the WGM wavelength positions are applied and used to quantify the adsorbed mass densities, which are then compared with the results of a comparative surface plasmon resonance (SPR) study

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurement of the direct CP violating charge asymmetry in B-+/- -> mu(+/-)nu D-mu(0) decays

We present the first measurement of the CP violating charge asymmetry in B-+/- -> mu(+/-)nu D-mu(0) decays using the full Run II integrated luminosity of 10.4 fb(-1) in proton-antiproton collisions collected with the D0 detector at the Fermilab Tevatron Collider. We measure a difference in the yield of B- and B+ mesons in these decays by fitting the reconstructed invariant mass distributions. This results in an asymmetry of A(mu D0) = [-0.14 +/- 0.20] %, which is consistent with standard model predictions.Department of Energy (United States of America); National Science Foundation (United States of America); Alternative Energies and Atomic Energy Commission (France); National Center for Scientific Research/National Institute of Nuclear and Particle Physics (France); Ministry of Education and Science of the Russian Federation (Russia); National Research Center "Kurchatov Institute" of the Russian Federation (Russia); Russian Foundation for Basic Research (Russia); National Council for the Development of Science and Technology (Brazil); Carlos Chagas Filho Foundation for the Support of Research in the State of Rio de Janeiro (Brazil); Department of Science and Technology (India); Department of Atomic Energy (India); Administrative Department of Science, Technology and Innovation (Colombia); National Council of Science and Technology (Mexico); National Research Foundation of Korea (Korea); Foundation for Fundamental Research on Matter (The Netherlands); Science and Technology Facilities Council (United Kingdom); Royal Society (United Kingdom); Ministry of Education, Youth and Sports (Czech Republic); Bundesministerium fur Bildung und Forschung (Federal Ministry of Education and Research) (Germany); Deutsche Forschungsgemeinschaft (German Research Foundation) (Germany); Science Foundation Ireland (Ireland); Swedish Research Council (Sweden); China Academy of Sciences (China); National Natural Science Foundation of China (China); Ministry of Education and Science of Ukraine (Ukraine)This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]