89,632 research outputs found
Neutron Electric Dipole Moment at Fixed Topology
We describe the finite volume effects of CP-odd quantities, such as the
neutron electric dipole moment and the anapole moment in the -vacuum,
under different topological sectors. We evaluate the three-point Green's
functions for the electromagnetic current in a fixed non-trivial topological
sector in order to extract these CP-odd observables. We discuss the role of
zero modes in the CP-odd Green's function and show that, in the quenched
approximation, there is a power divergence in the quark mass for CP-odd
quantities at finite volume.Comment: 12 pages, revised manuscript to be publishe
Examining the crossover from hadronic to partonic phase in QCD
It is argued that, due to the existence of two vacua -- perturbative and
physical -- in QCD, the mechanism for the crossover from hadronic to partonic
phase is hard to construct. The challenge is: how to realize the transition
between the two vacua during the gradual crossover of the two phases. A
possible solution of this problem is proposed and a mechanism for crossover,
consistent with the principle of QCD, is constructed. The essence of this
mechanism is the appearance and growing up of a kind of grape-shape
perturbative vacuum inside the physical one. A dynamical percolation model
based on a simple dynamics for the delocalization of partons is constructed to
exhibit this mechanism. The crossover from hadronic matter to sQGP as well as
the transition from sQGP to wQGP in the increasing of temperature is
successfully described by using this model with a temperature dependent
parameter.Comment: 4 pages, 4 figure
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Polaronic effect in the x-ray absorption spectra of La1-x Ca x MnO3 manganites.
X-ray absorption spectroscopy (XAS) is performed to study changes in the electronic structures of colossal magnetoresistance (CMR) and charged ordered (CO) La1-x Ca x MnO3 manganites with respect to temperature. The pre-edge features in O and Mn K-edge XAS spectra, which are highly sensitive to the local distortion of MnO6 octahedral, exhibit contrasting temperature dependence between CMR and CO samples. The seemingly counter-intuitive XAS temperature dependence can be reconciled in the context of polarons. These results help identify the most relevant orbital states associated with polarons and highlight the crucial role played by polarons in understanding the electronic structures of manganites
Consistent Anisotropic Repulsions for Simple Molecules
We extract atom-atom potentials from the effective spherical potentials that
suc cessfully model Hugoniot experiments on molecular fluids, e.g., and
. In the case of the resulting potentials compare very well with the
atom-atom potentials used in studies of solid-state propertie s, while for
they are considerably softer at short distances. Ground state (T=0K) and
room temperatu re calculations performed with the new potential resolve
the previous discrepancy between experimental and theoretical results.Comment: RevTeX, 5 figure
Analyzing Robustness of the Deep Reinforcement Learning Algorithm in Ramp Metering Applications Considering False Data Injection Attack and Defense
Ramp metering is the act of controlling on-going vehicles to the highway
mainlines. Decades of practices of ramp metering have proved that ramp metering
can decrease total travel time, mitigate shockwaves, decrease rear-end
collisions by smoothing the traffic interweaving process, etc. Besides
traditional control algorithm like ALINEA, Deep Reinforcement Learning (DRL)
algorithms have been introduced to build a finer control. However, two
remaining challenges still hinder DRL from being implemented in the real world:
(1) some assumptions of algorithms are hard to be matched in the real world;
(2) the rich input states may make the model vulnerable to attacks and data
noises. To investigate these issues, we propose a Deep Q-Learning algorithm
using only loop detectors information as inputs in this study. Then, a set of
False Data Injection attacks and random noise attack are designed to
investigate the robustness of the model. The major benefit of the model is that
it can be applied to almost any ramp metering sites regardless of the road
geometries and layouts. Besides outcompeting the ALINEA method, the Deep
Q-Learning method also shows a good robustness through training among very
different demands and geometries. For example, during the testing case in I-24
near Murfreesboro, TN, the model shows its robustness as it still outperforms
ALINEA algorithm under Fast Gradient Sign Method attacks. Unlike many previous
studies, the model is trained and tested in completely different environments
to show the capabilities of the model.Comment: 11 pages, 5 figure
Character expansion of Kac–Moody correction factors
A correction factor naturally arises in the theory of p-adic Kac–Moody groups. We expand the correction factor into a sum of irreducible characters of the underlying Kac–Moody algebra. We derive a formula for the coefficients which lie in the ring of power series with integral coefficients. In the case that the Weyl group is a universal Coxeter group, we show that the coefficients are actually polynomials
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