46,150 research outputs found
Low-Voltage High-Linearity Wideband Current Differencing Transconductance Amplifier and Its Application on Current-Mode Active Filter
A low-voltage high-linearity wideband current differencing transconductance amplifier (CDTA) is presented in this paper. The CDTA consists of a current differencing circuit and a cross-coupling transconductance circuit. The PSPICE simulations of the proposed CDTA show a good performance: -3dB frequency bandwith is about 900 MHz, low power consumption is 2.48 mW, input current linear range is ±100 µA and low current-input resistance is less than 20 Ω, high current-output resistance is more than 3 MΩ. PSpice simulations for a current-mode universal filter and a proposed high-order filter are also conducted, and the results verify the validity of the proposed CDTA
The LHC di-photon Higgs signal predicted by little Higgs models
Little Higgs theory naturally predicts a light Higgs boson whose most
important discovery channel at the LHC is the di-photon signal . In this work we perform a comparative study for this signal in
some typical little Higgs models, namely the littlest Higgs model (LH), two
littlest Higgs models with T-parity (named LHT-I and LHT-II) and the simplest
little Higgs modes (SLH). We find that compared with the Standard Model
prediction, the di-photon signal rate is always suppressed and the suppression
extent can be quite different for different models. The suppression is mild
(\lsim 10%) in the LH model but can be quite severe () in other
three models. This means that discovering the light Higgs boson predicted by
the little Higgs theory through the di-photon channel at the LHC will be more
difficult than discovering the SM Higgs boson.Comment: 17 pages, 4 figures, 1 tabl
BCS-BEC crossover in a relativistic boson-fermion model beyond mean field approximation
We investigate the fluctuation effect of the di-fermion field in the
crossover from Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein
condensate (BEC) in a relativistic superfluid. We work within the boson-fermion
model obeying a global U(1) symmetry. To go beyond the mean field approximation
we use Cornwall-Jackiw-Tomboulis (CJT) formalism to include higher order
contributions. The quantum fluctuations of the pairing condensate is provided
by bosons in non-zero modes, whose interaction with fermions gives the
two-particle-irreducible (2PI) effective potential. It changes the crossover
property in the BEC regime. With the fluctuations the superfluid phase
transition becomes the first order in grand canonical ensemble. We calculate
the condensate, the critical temperature and particle abundances as
functions of crossover parameter the boson mass.Comment: The model Lagrangian is re-formulated by decomposing the complex
scalar field into its real and imaginary parts. The anomalous propagators of
the complex scalar are then included at tree level. All numerical results are
updated. ReVTex 4, 13 pages, 10 figures, PRD accepted versio
PHENIX Measurement of High- Hadron-hadron and Photon-hadron Azimuthal Correlations
High- hadron-hadron correlations have been measured with the PHENIX
experiment in \Cu and \pp collisions at GeV. A
comparison of the jet widths and yields between the two colliding systems
allows us to study the medium effect on jets. We also present a first
measurement of direct photon-hadron correlations in \Au and \pp collisions.
We find that the near-side yields are consistent with zero in both systems. By
comparing the jet yields on the away side, we observe a suggestion of the
expected suppression of hadrons associated with photons in \Au collisions.Comment: 5 pages, proceeding for parallel talk on Quark Matter 200
Topological Weyl and Node-Line Semimetals in Ferromagnetic Vanadium-Phosphorous-Oxide -VOPO Compound
We propose that the topological semimetal features can co-exist with
ferromagnetic ground state in vanadium-phosphorous-oxide -VOPO
compound from first-principles calculations. In this magnetic system with
inversion symmetry, the direction of magnetization is able to manipulate the
symmetric protected band structures from a node-line type to a Weyl one in the
presence of spin-orbital-coupling. The node-line semimetal phase is protected
by the mirror symmetry with the reflection-invariant plane perpendicular to
magnetic order. Within mirror symmetry breaking due to the magnetization along
other directions, the gapless node-line loop will degenerate to only one pair
of Weyl points protected by the rotational symmetry along the magnetic axis,
which are largely separated in momentum space. Such Weyl semimetal phase
provides a nice candidate with the minimum number of Weyl points in a condensed
matter system. The results of surface band calculations confirm the non-trivial
topology of this proposed compound. This findings provide a realistic candidate
for the investigation of topological semimetals with time-reversal symmetry
breaking, particularly towards the realization of quantum anomalous Hall effect
in Weyl semimetals.Comment: 5 pages, 4 figure
SUSY Dark Matter In Light Of CDMS/XENON Limits
In this talk we briefly review the current CDMS/XENON constraints on the
neutralino dark matter in three popular supersymmetric models: the minimal
(MSSM), the next-to-minimal (NMSSM) and the nearly minimal (nMSSM). The
constraints from the dark matter relic density and various collider experiments
are also taken into account. The conclusion is that for each model the current
CDMS/XENON limits can readily exclude a large part of the parameter space
allowed by other constraints and the future SuperCDMS or XENON100 can cover
most of the allowed parameter space. The implication for the Higgs search at
the LHC is also discussed. It is found that in the currently allowed parameter
space the MSSM charged Higgs boson is quite unlikely to be discovered at the
LHC while the neutral Higgs bosons and may be accessible at the LHC in
the parameter space with a large parameter.Comment: talk given at 2nd International Workshop on Dark Matter, Dark Energy
and Matter-Antimatter Asymmetry, Nov 5-6, 2010, Hsinchu, Taiwan (to appear in
Int. J. Mod. Phys. D
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