169 research outputs found
Complete and Consistent Chiral Transport from Wigner Function Formalism
Recently there has been significant interest in understanding the macroscopic
quantum transport in a many-body system of chiral fermions. A natural framework
for describing such a system which is generally out of equilibrium, is the
transport equation for its phase space distribution function. In this paper, we
obtain a complete solution of the covariant chiral transport for massless
fermions, by starting from the general Wigner function formalism and carrying
out a complete and consistent semiclassical expansion up to
order. In particular, we clarify certain subtle and
confusing issues surrounding the Lorentz non-invariance and frame dependence
associated with the 3D chiral kinetic theory. We prove that such frame
dependence is uniquely and completely fixed by an unambiguous definition of the
correction to the distribution function in each
reference frame
Dynamical magnetic fields in heavy-ion collisions
The magnetic fields in heavy-ion collisions are important ingredients for
many interesting phenomena, such as the Chiral Magnetic Effect, Chiral Magnetic
Wave, the directed flow of mesons and the splitting of the spin
polarization of the /. Quantitative studies of these
phenomena however suffer from limited understanding on the dynamical evolution
of these fields in the medium created by the collisions, which remains a
critical and challenging problem. The initial magnetic fields from the
colliding nuclei decay very fast in the vacuum but their lifetime could be
extended through medium response due to electrically conducting quarks and
antiquarks. Here we perform a detailed analysis of such medium effect on the
dynamical magnetic fields by numerically solving the Maxwell's equations
concurrently with the expanding medium described by viscous hydrodynamics,
under the assumption of negligible back reaction of the fields on the fluid
evolution. Our results suggest a considerable enhancement of late time magnetic
fields, the magnitude of which depends sensitively on the fireball expansion as
well as the medium electric conductivity both before and during hydrodynamic
stage.Comment: 15 pages, 7 figure
Memristor Neural Network Design
Neural network, a powerful learning model, has archived amazing results. However, the current Von Neumann computing system–based implementations of neural networks are suffering from memory wall and communication bottleneck problems ascribing to the Complementary Metal Oxide Semiconductor (CMOS) technology scaling down and communication gap. Memristor, a two terminal nanosolid state nonvolatile resistive switching, can provide energy‐efficient neuromorphic computing with its synaptic behavior. Crossbar architecture can be used to perform neural computations because of its high density and parallel computation. Thus, neural networks based on memristor crossbar will perform better in real world applications. In this chapter, the design of different neural network architectures based on memristor is introduced, including spiking neural networks, multilayer neural networks, convolution neural networks, and recurrent neural networks. And the brief introduction, the architecture, the computing circuits, and the training algorithm of each kind of neural networks are presented by instances. The potential applications and the prospects of memristor‐based neural network system are discussed
Evolution of topological charge through chiral anomaly transport
Built upon the state-of-the-art model a multiphase transport (AMPT), we
develop a new module of chiral anomaly transport (CAT), which can trace the
evolution of the initial topological charge of gauge field created through
sphaleron transition at finite temperature and external magnetic field in heavy
ion collisions. The eventual experimental signals of chiral magnetic
effect(CME) can be measured. The CAT explicitly shows the generation and
evolution of the charge separation, and the signals of CME through the CAT are
quantitatively in agreement with the experimental measurements in Au+Au
collision at , and the centrality dependence of the CME
fraction follows that of the fireball temperature.Comment: 7 pages, 6 figure
The rotation effect on the thermodynamics of the QCD matter
In this study, we investigate the impact of rotation on the thermodynamic
characteristics of QCD matter using the three-flavor NJL model. We examine the
temperature, quark chemical potential, and angular velocity dependencies of key
thermodynamic quantities, such as the trace anomaly, specific heat, speed of
sound, angular momentum, and moment of inertia. As the main finding of our
analysis, we observe that the speed of sound exhibits a nonmonotonic behavior
as the angular velocity changes.Comment: 18 pages, 19 figure
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