3,075 research outputs found
Critical field theory of the Kondo lattice model in two dimensions
In the context of the U(1) slave boson theory we derive a critical field
theory near the quantum critical point of the Kondo lattice model in two
spatial dimensions. First we argue that strong gauge fluctuations in the U(1)
slave boson theory give rise to confinement between spinons and holons, thus
causing "neutralized" spinons in association with the slave boson U(1) gauge
field. Second we show that critical fluctuations of Kondo singlets near the
quantum critical point result in a new U(1) gauge field. This emergent gauge
field has nothing to do with the slave boson U(1) gauge field. Third we find
that the slave boson U(1) gauge field can be exactly integrated out in the low
energy limit. As a result we find a critical field theory in terms of
renormalized conduction electrons and neutralized spinons interacting via the
new emergent U(1) gauge field. Based on this critical field theory we obtain
the temperature dependence of specific heat and the imaginary part of the
self-energy of the renormalized electrons. These quantities display non-Fermi
liquid behavior near the quantum critical point
Molecular Dynamics Simulation of Ga Penetration along Grain Boundaries in Al: a Dislocation Climb Mechanism
Many systems where a liquid metal is in contact with a polycrystalline solid
exhibit deep liquid grooves where the grain boundary meets the solid-liquid
interface. For example, liquid Ga quickly penetrates deep into grain boundaries
in Al, leading to intergranular fracture under very small stresses. We report
on a series of molecular dynamics simulations of liquid Ga in contact with an
Al bicrystal. We identify the mechanism for liquid metal embrittlement, develop
a new model for it, and show that is in excellent agreement with both
simulation and experimental data
Modeling and Exact Analysis of a Production Line with Two Unreliable Batch Machines and a Finite Buffer: Part I - Full Batches
A Practical Guide for Successful Revisions and Engagements with Reviewers
Revising a manuscript after receiving a revise-and-resubmit decision from a top-tier journal can be just as arduous as developing a new paper from scratch. In this editorial, based on our experiences revising papers over the years, we provide roadmaps and guidelines for completing successful revisions for top journals. In doing so, we offer practical tips for completing three major tasks—making sense of a review packet, revising a manuscript, and crafting responses to reviewer comments. We conclude by recommending that authors be active reviewers themselves because, by doing so, they can develop their own insights on how peer review works and become more skillful at revising their papers and responding to reviewers
A characterization of linear operators that preserve isolation numbers
We obtain characterizations of Boolean linear operators that preserve some of the isolation numbers of Boolean matrices. In particular, we show that the following are equivalent: (1) preserves the isolation number of all matrices; (2) preserves the set of matrices with isolation number one and the set of those with isolation number for some ; (3) for , preserves matrices
with isolation number , and those with isolation number , (4) maps to and preserves the set of matrices of isolation number 2; (5) is a -operator, that is, for fixed permutation matrices and , matrix ~ or, and where is the transpose of
Competition between Kondo and RKKY correlations in the presence of strong randomness
We propose that competition between Kondo and magnetic correlations results
in a novel universality class for heavy fermion quantum criticality in the
presence of strong randomness. Starting from an Anderson lattice model with
disorder, we derive an effective local field theory in the dynamical mean-field
theory (DMFT) approximation, where randomness is introduced into both
hybridization and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. Performing
the saddle-point analysis in the U(1) slave-boson representation, we reveal its
phase diagram which shows a quantum phase transition from a spin liquid state
to a local Fermi liquid phase. In contrast with the clean limit of the Anderson
lattice model, the effective hybridization given by holon condensation turns
out to vanish, resulting from the zero mean value of the hybridization coupling
constant. However, we show that the holon density becomes finite when variance
of hybridization is sufficiently larger than that of the RKKY coupling, giving
rise to the Kondo effect. On the other hand, when the variance of hybridization
becomes smaller than that of the RKKY coupling, the Kondo effect disappears,
resulting in a fully symmetric paramagnetic state, adiabatically connected with
the spin liquid state of the disordered Heisenberg model. .....
Burst and Biaxial Creep of Thin-Walled Tubing of Low c/a-Ratio HCP Metals
AbstractThin-walled tubing used in various structures are made of low c/a-ratio hcp metals such as Zr and Ti based alloys, and their integrity to internal pressures is of prime importance in the life of these engineering structures. We summarize here ome of the work performed on Zircaloy cladding commonly used in LWRs as thin walled tubing as well as Cp-Ti and Ti3Al2.5V that find applications in aerospace industry. Considered here are three different types of tests: (i) burst tests using closed- end internal pressurization, (ii) uniaxial ring tests for characterization of hoop creep properties and (iii) hoop creep under biaxial internal pressurization. Burst and ring tests yielded identical hoop creep and rupture characteristics indicating the utility of ring tests to replace burst tests. Importance of transitions in creep mechanisms with decreased stress levels in predicting in-service dimensional changes is emphasized
Generation of mechanical squeezing via magnetic dipoles on cantilevers
A scheme to squeeze the center-of-mass motional quadratures of a quantum
mechanical oscillator below its standard quantum limit is proposed and analyzed
theoretically. It relies on the dipole-dipole coupling between a magnetic
dipole mounted on the tip of a cantilever to equally oriented dipoles located
on a mesoscopic tuning fork. We also investigate the influence of several
sources of noise on the achievable squeezing, including classical noise in the
driving fork and the clamping noise in the oscillator. A detection of the state
of the cantilever based on state transfer to a light field is considered. We
investigate possible limitations of that scheme.Comment: 11 pages, 11 figures, submitted to PR
Estimating Net Operating Income Growth for Modeling U.S. Apartment Property Capitalization Rates
The properties of income-to-price ratios in asset markets have potentially far reaching implications for understanding investor behavior. Prevailing levels of commercial real estate (CRE) capitalization rates, similar to price / earnings ratios for stocks and owner equivalent rent-to-price relatives for houses, may foretell future investment returns and income growth rates. In CRE capitalization rate models, rent growth rates often proxy for the net operating income (NOI) growth rates. Empirical studies of capitalization rate predictive powers produce inconsistent results that may be due either to the use of these rent growth proxies, model misspecification, or both. We use a novel approach for generating NOI growth rate estimates that involves combining survey rent and the expense growth rates for U.S. apartments. Our GARCH analysis of the capitalization rate spread process using the estimated NOI growth rate produces theoretically consistent results. Importantly, we demonstrate efficiency gains from using our NOI growth rate estimates relative to traditional rent growth rate
Einstein Manifolds As Yang-Mills Instantons
It is well-known that Einstein gravity can be formulated as a gauge theory of
Lorentz group where spin connections play a role of gauge fields and Riemann
curvature tensors correspond to their field strengths. One can then pose an
interesting question: What is the Einstein equations from the gauge theory
point of view? Or equivalently, what is the gauge theory object corresponding
to Einstein manifolds? We show that the Einstein equations in four dimensions
are precisely self-duality equations in Yang-Mills gauge theory and so Einstein
manifolds correspond to Yang-Mills instantons in SO(4) = SU(2)_L x SU(2)_R
gauge theory. Specifically, we prove that any Einstein manifold with or without
a cosmological constant always arises as the sum of SU(2)_L instantons and
SU(2)_R anti-instantons. This result explains why an Einstein manifold must be
stable because two kinds of instantons belong to different gauge groups,
instantons in SU(2)_L and anti-instantons in SU(2)_R, and so they cannot decay
into a vacuum. We further illuminate the stability of Einstein manifolds by
showing that they carry nontrivial topological invariants.Comment: v4; 17 pages, published version in Mod. Phys. Lett.
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