10,076 research outputs found
Effects of unparticle on top spin correlation at the Large Hadron Collider
We study effects of the scale invariant hidden sector, unparticle, proposed
by Georgi, on top spin correlation at the Large Hadron Collider. Assuming no
flavor changing interaction between the unparticles and the Standard Model
particles, there arises the top-antitop quark pair production process through
virtual unparticle exchanges in the s-channel in addition to the Standard Model
processes. In particular, we consider contributions of scalar and vector
unparticles and find that these make sizable deviations of the top spin
correlation from the Standard Model one.Comment: 29 pages, 1 table, 12 figures, 2 figures added, typos in captions
corrected, version accepted for publication in PR
Spin superconductor in ferromagnetic graphene
We show a spin superconductor (SSC) in ferromagnetic graphene as the
counterpart to the charge superconductor, in which a spin-polarized
electron-hole pair plays the role of the spin `Cooper pair' with
a neutral charge. We present a BCS-type theory for the SSC. With the
`London-type equations' of the super-spin-current density, we show the
existence of an electric `Meissner effect' against a spatial varying electric
field. We further study a SSC/normal conductor/SSC junction and predict a
spin-current Josephson effect.Comment: 6 pages, 4 figure
Abelian and non-abelian anyons in integer quantum anomalous Hall effect and topological phase transitions via superconducting proximity effect
We study the quantum anomalous Hall effect described by a class of
two-component Haldane models on square lattices. We show that the latter can be
transformed into a pseudospin triplet p+ip-wave paired superfluid. In the long
wave length limit, the ground state wave function is described by Halperin's
(1,1,-1) state of neutral fermions analogous to the double layer quantum Hall
effect. The vortex excitations are charge e/2 abelian anyons which carry a
neutral Dirac fermion zero mode. The superconducting proximity effect induces
`tunneling' between `layers' which leads to topological phase transitions
whereby the Dirac fermion zero mode fractionalizes and Majorana fermions emerge
in the edge states. The charge e/2 vortex excitation carrying a Majorana zero
mode is a non-abelian anyon. The proximity effect can also drive a conventional
insulator into a quantum anomalous Hall effect state with a Majorana edge mode
and the non-abelian vortex excitations.Comment: 6 pages, 4 figures, accepted by Phys. Rev.
Delay-dependent robust stability of stochastic delay systems with Markovian switching
In recent years, stability of hybrid stochastic delay systems, one of the important issues in the study of stochastic systems, has received considerable attention. However, the existing results do not deal with the structure of the diffusion but estimate its upper bound, which induces conservatism. This paper studies delay-dependent robust stability of hybrid stochastic delay systems. A delay-dependent criterion for robust exponential stability of hybrid stochastic delay systems is presented in terms of linear matrix inequalities (LMIs), which exploits the structure of the diffusion. Numerical examples are given to verify the effectiveness and less conservativeness of the proposed method
Identification of the white dwarf companion to millisecond pulsar J2317+1439
We report identification of the optical counterpart to the companion of the
millisecond pulsar J2317+1439. At the timing position of the pulsar, we find an
object with , and . The
magnitudes and colors of the object are consistent with it being a white dwarf.
By comparing with white dwarf cooling models, we estimate that it has a mass of
M, an effective temperature of
K and a cooling age of Gyr. Combining our
results with published constraints on the orbital parameters obtained through
pulsar timing, we estimate the pulsar mass to be
M. Although the constraint on the pulsar mass is still weak, there is
a significant possibility that the pulsar could be more massive than two solar
mass.Comment: 7 pages, 6 figures, accepted for publication in Ap
A new metric for rotating charged Gauss-Bonnet black holes in AdS spaces
This paper presents a new metric for slowly rotating charged Gauss-Bonnet
black holes in higher dimensional anti-de Sitter spaces. Taking the angular
momentum parameter up to second order, the slowly rotating charged black
hole solutions are obtained by working directly in the action.Comment: 11 pages and accepted by Chin. Phys.
Modelling and control of the flame temperature distribution using probability density function shaping
This paper presents three control algorithms for the output probability density function (PDF) control of the 2D and 3D flame distribution systems. For the 2D flame distribution systems, control methods for both static and dynamic flame systems are presented, where at first the temperature distribution of the gas jet flames along the cross-section is approximated. Then the flame energy distribution (FED) is obtained as the output to be controlled by using a B-spline expansion technique. The general static output PDF control algorithm is used in the 2D static flame system, where the dynamic system consists of a static temperature model of gas jet flames and a second-order actuator. This leads to a second-order closed-loop system, where a singular state space model is used to describe the dynamics with the weights of the B-spline functions as the state variables. Finally, a predictive control algorithm is designed for such an output PDF system. For the 3D flame distribution systems, all the temperature values of the flames are firstly mapped into one temperature plane, and the shape of the temperature distribution on this plane can then be controlled by the 3D flame control method proposed in this paper. Three cases are studied for the proposed control methods and desired simulation results have been obtained
The scalars from the topcolor scenario and the spin correlations of the top pair production at the LHC
The topcolor scenario predicts the existences of some new scalars. In this
paper, we consider the contributions of these new particles to the observables,
which are related to the top quark pair () production at the LHC. It
is found that these new particles can generate significant corrections to the
production cross section and the spin correlations.Comment: 23 pages, 4 figures; discussions and references added; agrees with
published versio
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