13,175 research outputs found
Ultra-low-frequency electromagnetic waves as signals and special counterparts of gravitational waves (from binary mergers) having tensorial and possible nontensorial polarizations
Gravitational waves (GWs, from binary merger) interacting with super-strong
magnetic fields of the neutron star (in the same binary system), would lead to
perturbed electromagnetic waves [EMWs, in the same frequencies of these GWs,
partially in the ultra-low-frequency (ULF) band for the EMWs]. Such perturbed
ULF-EMWs are not only the signals, but also a new type of special EM
counterparts of the GWs. Here, generation of the perturbed ULF-EMWs is
investigated for the first time, and the strengths of their magnetic components
are estimated to be around 10^{-12}Tesla to 10^{-17}Tesla (in fISCO) at the
Earth for various cases [not including the influence of interstellar medium
(ISM)].The components with higher frequencies of the ULF-EMWs (e.g., especially
produced by the GWs of the post-merger stage) above 1.8kHz (typical plasma
frequency around solar system in the Milky way), could propagate through the
ISM from the source until the Earth, and the perturbed ULF-EMWs will be
reprocessed before they arrived at the Earth due to the ISM. Also, the
waveforms of the perturbed ULF-EMWs will be modified into shapes different but
related to the waveforms of the GWs, by the amplification process during the
binary mergers which could amplify the magnetic fields into 10^{12}Tesla or
even higher. Specific connection relationships between the polarizations of the
perturbed ULF-EMWs and the polarizations (tensorial and possible nontensorial)
of the GWs of binary mergers, are also addressed here. Characteristic
properties of the perturbed ULF-EMWs (which would bring us some different new
information of fundamental properties of the gravity and Universe) will be very
helpful for extracting the signals from background noise for possible
observations in the future.Comment: 16 pages, 6 figure
Counting Multiplicities in a Hypersurface over a Number Field
We fix a counting function of multiplicities of algebraic points in a
projective hypersurface over a number field, and take the sum over all
algebraic points of bounded height and fixed degree. An upper bound for the sum
with respect to this counting function will be given in terms of the degree of
the hypersurface, the dimension of the singular locus, the upper bounds of
height, and the degree of the field of definition.Comment: 23 page
A twisted -Neumann problem and Toeplitz -tuples from singularity theory
A twisted -Neumann problem associated to a singularity
is established. By constructing the connection to the
Koszul complex for toeplitz -tuples on Bergman spaces
, we can solve this -Neumann problem. Moreover, we
can compute the cohomology of the holomorphic Koszul complex
explicitlyComment: 20 page
Stability of Steady Solutions to Reaction-Hyperbolic Systems for Axonal Transport
This paper is concerned with the stability of steady solutions to
initial-boundary-value problems of reaction-hyperbolic systems for axonal
transport. Under proper structural assumptions, we clarify the relaxation
structure of the reaction-hyperbolic systems and show the time-asymptotic
stability of steady solutions or relaxation boundary-layers
Improving spin-based noise sensing by adaptive measurements
Localized spins in the solid state are attracting widespread attention as
highly sensitive quantum sensors with nanoscale spatial resolution and
fascinating applications. Recently, adaptive measurements were used to improve
the dynamic range for spin-based sensing of deterministic Hamiltonian
parameters. Here we explore a very different direction -- spin-based adaptive
sensing of random noises. First, we identify distinguishing features for the
sensing of magnetic noises compared with the estimation of deterministic
magnetic fields, such as the different dependences on the spin decoherence, the
different optimal measurement schemes, the absence of the modulo-2\pi phase
ambiguity, and the crucial role of adaptive measurement. Second, we perform
numerical simulations that demonstrate significant speed up of the
characterization of the spin decoherence time via adaptive measurements. This
paves the way towards adaptive noise sensing and coherence protection.Comment: 13 pages, 7 figure
Simulating the Chiral Magnetic Wave in a Box System
The chiral magnetic wave from the interplay between the chiral magnetic
effect and the chiral separation effect is simulated in a box system with the
periodic boundary condition based on the chiral kinetic equations of motion.
Simulation results are compared with available limits from theoretical
derivations, and effects of the temperature, the magnetic field, and the
specific shear viscosity on the key properties of the chiral magnetic wave are
discussed. Our study serves as a baseline for further simulations of chiral
anomalies in relativistic heavy-ion collisions.Comment: 7 pages, 5 figure
Strange Quark Stars as Probe of Dark Matter
We demonstrate that the observation of old strange quark stars (SQSs) can set
important limits on the scattering cross sections between the light
quarks and the non-interacting scalar dark matter (DM). By analyzing a set of
1403 of solitary pulsarlike compact stars in the Milky Way, we find the old
solitary pulsar PSR J1801-0857D can set the most stringent upper limits on
or the DM-proton scattering cross sections . By converting
into based on effective operator analyses, we show the
resulting limit by assuming PSR J1801-0857D to be a SQS could be
comparable with that of the current direct detection experiments but much
weaker (by several orders of magnitude) than that obtained by assuming PSR
J1801-0857D to be a neutron star (NS), which requires an extremely small
far beyond the limits of direct detection experiments. Our findings
imply that the old pulsars are favored to be SQSs rather than NSs if the scalar
DM were observed by future terrestrial experiments.Comment: 6 pages, 4 figures. Some results updated and discussions added.
Accepted version to appear in Ap
Simulating chiral anomalies with spin dynamics
Considering that the chiral kinetic equations of motion (CEOM) can be derived
from the spin kinetic equations of motion (SEOM) for massless particles with
approximations, we simulate the chiral anomalies by using the latter in a box
system with the periodic boundary condition under a uniform external magnetic
field. We found that the chiral magnetic effect is weaker while the damping of
the chiral magnetic wave is stronger from the SEOM compared with that from the
CEOM. In addition, effects induced by chiral anomalies from the SEOM are less
sensitive to the decay of the magnetic field than from the CEOM due to the spin
relaxation process.Comment: 6 pages, 6 figure
Giant Magnons and Spiky Strings on S^3 with B-field
We study solutions for a rotating string on S^3 with a background NS-NS
B-field and show the existence of spiky string and giant magnon as two limiting
solutions. We make a connection to the sine-Gordon model via the Polyakov
worldsheet action and study the effect of B-field. In particular, we find the
magnon solution can be mapped to the excitation of a fractional spin chain. We
conjecture a B-deformed SYM to be the gauge theory dual to this background.Comment: 22 pages, 3 figures, more references adde
Training Generative Adversarial Networks with Binary Neurons by End-to-end Backpropagation
We propose the BinaryGAN, a novel generative adversarial network (GAN) that
uses binary neurons at the output layer of the generator. We employ the
sigmoid-adjusted straight-through estimators to estimate the gradients for the
binary neurons and train the whole network by end-to-end backpropogation. The
proposed model is able to directly generate binary-valued predictions at test
time. We implement such a model to generate binarized MNIST digits and
experimentally compare the performance for different types of binary neurons,
GAN objectives and network architectures. Although the results are still
preliminary, we show that it is possible to train a GAN that has binary neurons
and that the use of gradient estimators can be a promising direction for
modeling discrete distributions with GANs. For reproducibility, the source code
is available at https://github.com/salu133445/binarygan
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