6,643 research outputs found
Energy average formula of photon gas rederived by using the generalized Hermann-Feynman theorem
By virtue of the generalized Hermann-Feynmam theorem and the method of
characteristics we rederive energy average formula of photon gas, this is
another useful application of the theorem.Comment: 2 page
Inhibition of Return in the visual field
Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. To test this possibility, we examined this eccentricity effect in two conditions: the same-size condition in which identical stimuli were used at different eccentricities, and the size-scaling condition in which stimuli were scaled according to the cortical magnification factor (M-scaling), thus stimuli being larger at the more peripheral locations. The results showed that the magnitude of IOR was significantly stronger in the peripheral relative to the perifoveal visual field, and this eccentricity effect was independent of the manipulation of stimulus size (same-size or size-scaling). These results suggest a robust eccentricity effect of IOR which cannot be eliminated by M-scaling. Underlying neural mechanisms of the eccentricity effect of IOR are discussed with respect to both cortical and subcortical structures mediating attentional control in the perifoveal and peripheral visual field
Monte Carlo Simulation of HERD Calorimeter
The High Energy cosmic-Radiation Detection (HERD) facility onboard China's
Space Station is planned for operation starting around 2020 for about 10 years.
It is designed as a next generation space facility focused on indirect dark
matter search, precise cosmic ray spectrum and composition measurements up to
the knee energy, and high energy gamma-ray monitoring and survey. The
calorimeter plays an essential role in the main scientific objectives of HERD.
A 3-D cubic calorimeter filled with high granularity crystals as active
material is a very promising choice for the calorimeter. HERD is mainly
composed of a 3-D calorimeter (CALO) surrounded by silicon trackers (TK) from
all five sides except the bottom. CALO is made of 9261 cubes of LYSO crystals,
corresponding to about 55 radiation lengths and 3 nuclear interaction lengths,
respectively. Here the simulation results of the performance of CALO with
GEANT4 and FLUKA are presented: 1) the total absorption CALO and its absorption
depth for precise energy measurements (energy resolution: 1\% for electrons and
gamma-rays beyond 100 GeV, 20\% for protons from 100 GeV to 1 PeV); 2) its
granularity for particle identification (electron/proton separation power
better than ); 3) the homogenous geometry for detecting particles
arriving from every unblocked direction for large effective geometrical factor
(3 for electron and diffuse gamma-rays, 2 for cosmic ray nuclei); 4) expected observational results such
as gamma-ray line spectrum from dark matter annihilation and spectrum
measurement of various cosmic ray chemical components
The Classical Limit of Quantum Mechanics and the Fejer Sum of the Fourier Series Expansion of a Classical Quantity
In quantum mechanics, the expectation value of a quantity on a quantum state,
provided that the state itself gives in the classical limit a motion of a
particle in a definite path, in classical limit goes over to Fourier series
form of the classical quantity. In contrast to this widely accepted point of
view, a rigorous calculation shows that the expectation value on such a state
in classical limit exactly gives the Fej\'{e}r's arithmetic mean of the partial
sums of the Fourier series
Quenched Charmed Meson Spectra using Tadpole Improved Quark Action on Anisotropic Lattices
Charmed meson charmonium spectra are studied with improved quark actions on
anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion
relations for 4 lowest lattice momentum modes with quark mass values ranging
from the strange quark to charm quark with 3 different values of gauge coupling
and 4 different values of bare speed of light . With the bare
speed of light parameter tuned in a mass-dependent way, we study the mass
spectra of , , ,
, and mesons.
The results extrapolated to the continuum limit are compared with the
experiment and qualitative agreement is found.Comment: 8 pages, 2 figures, latex fil
The Euler Number of Bloch States Manifold and the Quantum Phases in Gapped Fermionic Systems
We propose a topological Euler number to characterize nontrivial topological
phases of gapped fermionic systems, which originates from the Gauss-Bonnet
theorem on the Riemannian structure of Bloch states established by the real
part of the quantum geometric tensor in momentum space. Meanwhile, the
imaginary part of the geometric tensor corresponds to the Berry curvature which
leads to the Chern number characterization. We discuss the topological numbers
induced by the geometric tensor analytically in a general two-band model. As an
example, we show that the zero-temperature phase diagram of a transverse field
XY spin chain can be distinguished by the Euler characteristic number of the
Bloch states manifold in a (1+1)-dimensional Bloch momentum space
Ultrahigh sensitivity of slow-light gyroscope
Slow light generated by Electromagnetically Induced Transparency is extremely
susceptible with respect to Doppler detuning. Consequently, slow-light
gyroscopes should have ultrahigh sensitivity
Finite-Temperature Scaling of Magnetic Susceptibility and Geometric Phase in the XY Spin Chain
We study the magnetic susceptibility of 1D quantum XY model, and show that
when the temperature approaches zero, the magnetic susceptibility exhibits the
finite-temperature scaling behavior. This scaling behavior of the magnetic
susceptibility in 1D quantum XY model, due to the quantum-classical mapping,
can be easily experimentally tested. Furthermore, the universality in the
critical properties of the magnetic susceptibility in quantum XY model is
verified. Our study also reveals the close relation between the magnetic
susceptibility and the geometric phase in some spin systems, where the quantum
phase transitions are driven by an external magnetic field.Comment: 6 pages, 4 figures, get accepted for publication by J. Phys. A: Math.
Theo
Magnetic properties of an SU(4) spin-orbital chain
In this paper, we study the magnetic properties of the one-dimensional SU(4)
spin-orbital model by solving its Bethe ansatz solution numerically. It is
found that the magnetic properties of the system for the case of
differs from that for the case of . The magnetization curve and
susceptibility are obtained for a system of 200 sites. For , the
phase diagram depending on the magnetic field and the ratio of Land\'e factors,
, is obtained. Four phases with distinct magnetic properties are
found.Comment: 4 pages, 2 figure
- …