2,175 research outputs found
Nuclear and Particle Physics applications of the Bohm Picture of Quantum Mechanics
Approximation methods for calculating individual particle/ field motions in
spacetime at the quantum level of accuracy (a key feature of the Bohm Picture
of Quantum Mechanics (BP)), are studied. Modern textbook presentations of
Quantum Theory are used throughout, but only to provide the necessary, already
existing, tested formalisms and calculational techniques. New coherent
insights, reinterpretations of old solutions and results, and new (in principle
testable) quantitative and qualitative predictions, can be obtained on the
basis of the BP that complete the standard type of postdictions and
predictions.Comment: 41 page
Extended bound states and resonances of two fermions on a periodic lattice
The high- cuprates are possible candidates for d-wave superconductivity,
with the Cooper pair wave function belonging to a non-trivial irreducible
representation of the lattice point group. We argue that this d-wave symmetry
is related to a special form of the fermionic kinetic energy and does not
require any novel pairing mechanism. In this context, we present a detailed
study of the bound states and resonances formed by two lattice fermions
interacting via a non-retarded potential that is attractive for nearest
neighbors but repulsive for other relative positions. In the case of strong
binding, a pair formed by fermions on adjacent lattice sites can have a small
effective mass, thereby implying a high condensation temperature. For a weakly
bound state, a pair with non-trivial symmetry tends to be smaller in size than
an s-wave pair. These and other findings are discussed in connection with the
properties of high- cuprate superconductors.Comment: 21 pages, RevTeX, 4 Postscript figures, arithmetic errors corrected.
An abbreviated version (no appendix) appeared in PRB on March 1, 199
The Pfaffian solution of a dimer-monomer problem: Single monomer on the boundary
We consider the dimer-monomer problem for the rectangular lattice. By mapping
the problem into one of close-packed dimers on an extended lattice, we rederive
the Tzeng-Wu solution for a single monomer on the boundary by evaluating a
Pfaffian. We also clarify the mathematical content of the Tzeng-Wu solution by
identifying it as the product of the nonzero eigenvalues of the Kasteleyn
matrix.Comment: 4 Pages to appear in the Physical Review E (2006
Comment on "Boson-fermion model beyond the mean-field approximation"
In a recent paper [A.S.Alexandrov, J.Phys.:Condens.Matter 8, 6923 (1996);
cond-mat/9603111], it has been suggested that there is no Cooper pairing in
boson-fermion models of superconductivity. We show that this conjecture is
based on an inconsistent approximation that violates an exact identity. Quite
generally, the divergence of the fermion t-matrix (the Thouless criterion) is
accompanied by the condensation of a boson mode.Comment: LaTeX, 5 pages, 2style files included, 4 embedded EPS figures,
submitted to J.Phys.:Condens.Matte
Yeast autonomously replicating sequence binding factor is involved in nucleotide excision repair
Nucleotide excision repair (NER) in yeast is effected by the concerted action of a large complex of proteins. Recently, we identified a stable subcomplex containing the yeast Rad7 and Rad16 proteins. Here, we report the identification of autonomously replicating sequence binding factor 1 (ABF1) as a component of the Rad7/Rad16 NER subcomplex. Yeast ABF1 protein is encoded by an essential gene required for DNA replication, transcriptional regulation, and gene silencing. We show that ABF1 plays a direct role in NER in vitro. Additionally, consistent with a role of ABF1 protein in NER in vivo, we show that certain temperature-sensitive abf1 mutant strains that are defective in DNA replication are specifically defective in the removal of photoproducts by NER and are sensitive to killing by ultraviolet (UV) radiation. These studies define a novel and unexpected role for ABF1 protein during NER in yeast
Quantum Kinks: Solitons at Strong Coupling
We examine solitons in theories with heavy fermions. These ``quantum''
solitons differ dramatically from semi-classical (perturbative) solitons
because fermion loop effects are important when the Yukawa coupling is strong.
We focus on kinks in a --dimensional theory coupled to
fermions; a large- expansion is employed to treat the Yukawa coupling
nonperturbatively. A local expression for the fermion vacuum energy is derived
using the WKB approximation for the Dirac eigenvalues. We find that fermion
loop corrections increase the energy of the kink and (for large ) decrease
its size. For large , the energy of the quantum kink is proportional to ,
and its size scales as , unlike the classical kink; we argue that these
features are generic to quantum solitons in theories with strong Yukawa
couplings. We also discuss the possible instability of fermions to solitons.Comment: 21 pp. + 2 figs., phyzzx, JHU-TIPAC-92001
Vacuum energy in a spherically symmetric background field
The vacuum energy of a scalar field in a spherically symmetric background
field is considered. It is expressed through the Jost function of the
corresponding scattering problem. The renormalization is discussed in detail
and performed using the uniform asymptotic expansion of the Jost function. The
method is demonstrated in a simple explicit example.Comment: 14 pages, 1 Postscript figur
Bogomol'nyi Equations of Maxwell-Chern-Simons vortices from a generalized Abelian Higgs Model
We consider a generalization of the abelian Higgs model with a Chern-Simons
term by modifying two terms of the usual Lagrangian. We multiply a dielectric
function with the Maxwell kinetic energy term and incorporate nonminimal
interaction by considering generalized covariant derivative. We show that for a
particular choice of the dielectric function this model admits both topological
as well as nontopological charged vortices satisfying Bogomol'nyi bound for
which the magnetic flux, charge and angular momentum are not quantized. However
the energy for the topolgical vortices is quantized and in each sector these
topological vortex solutions are infinitely degenerate. In the nonrelativistic
limit, this model admits static self-dual soliton solutions with nonzero finite
energy configuration. For the whole class of dielectric function for which the
nontopological vortices exists in the relativistic theory, the charge density
satisfies the same Liouville equation in the nonrelativistic limit.Comment: 30 pages(4 figures not included), RevTeX, IP/BBSR/93-6
Flux tube dynamics in the dual superconductor
We study plasma oscillations in a flux tube of the dual superconductor model
of 't Hooft and Mandelstam. A magnetic condensate is coupled to an
electromagnetic field by its dual vector potential, and fixed electric charges
set up a flux tube. An electrically charged fluid (a quark plasma) flows in the
tube and screens the fixed charges via plasma oscillations. We investigate both
Type I and Type II superconductors, with plasma frequencies both above and
below the threshold for radiation into the Higgs vacuum. We find strong
radiation of electric flux into the superconductor in all regimes, and argue
that this invalidates the use of the simplest dual superconductor model for
dynamical problems.Comment: 25 pages Revtex with 11 EPS figure
zeek-osquery: Host-Network Correlation for Advanced Monitoring and Intrusion Detection
Intrusion Detection Systems (IDSs) can analyze network traffic for signs of
attacks and intrusions. However, encrypted communication limits their
visibility and sophisticated attackers additionally try to evade their
detection. To overcome these limitations, we extend the scope of Network IDSs
(NIDSs) with additional data from the hosts. For that, we propose the
integrated open-source zeek-osquery platform that combines the Zeek IDS with
the osquery host monitor. Our platform can collect, process, and correlate host
and network data at large scale, e.g., to attribute network flows to processes
and users. The platform can be flexibly extended with own detection scripts
using already correlated, but also additional and dynamically retrieved host
data. A distributed deployment enables it to scale with an arbitrary number of
osquery hosts. Our evaluation results indicate that a single Zeek instance can
manage more than 870 osquery hosts and can attribute more than 96% of TCP
connections to host-side applications and users in real-time.Comment: Accepted for publication at ICT Systems Security and Privacy
Protection (IFIP) SEC 202
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