9,629 research outputs found
Symmetries in nonlinear Bethe-Heitler process
Nonlinear Bethe-Heitler process in a bichromatic laser field is investigated
using strong-field QED formalism. Symmetry properties of angular distributions
of created pairs are analyzed. These properties are showed to be
governed by a behavior of the vector potential characterizing the laser field,
rather than by the respective electric field component.Comment: 4 pages, 4 figure
Scaling Behavior of Heavy Fermion Metals
Strongly correlated Fermi systems are fundamental systems in physics that are
best studied experimentally, which until very recently have lacked theoretical
explanations. This review discusses the construction of a theory and the
analysis of phenomena occurring in strongly correlated Fermi systems such as
heavy-fermion (HF) metals and two-dimensional (2D) Fermi systems. It is shown
that the basic properties and the scaling behavior of HF metals can be
described within the framework of a fermion condensation quantum phase
transition (FCQPT) and extended quasiparticle paradigm that allow us to explain
the non-Fermi liquid behavior observed in strongly correlated Fermi systems. In
contrast to the Landau paradigm stating that the quasiparticle effective mass
is a constant, the effective mass of new quasiparticles strongly depends on
temperature, magnetic field, pressure, and other parameters. Having analyzed
collected facts on strongly correlated Fermi systems with quite different
microscopic nature, we find these to exhibit the same non-Fermi liquid behavior
at FCQPT. We show both analytically and using arguments based entirely on the
experimental grounds that the data collected on very different strongly
correlated Fermi systems have a universal scaling behavior, and materials with
strongly correlated fermions can unexpectedly be uniform in their diversity.
Our analysis of strongly correlated systems such as HF metals and 2D Fermi
systems is in the context of salient experimental results. Our calculations of
the non-Fermi liquid behavior, the scales and thermodynamic, relaxation and
transport properties are in good agreement with experimental facts.Comment: 100 pages, 66 figures, to appear in Physics Report
Tame group actions on central simple algebras
We study actions of linear algebraic groups on finite-dimensional central
simple algebras. We describe the fixed algebra for a broad class of such
actions.Comment: 19 pages, LaTeX; slightly revised; final version will appear in
Journal of Algebr
Scaling in Dynamic Susceptibility of Herbertsmithite and Heavy-Fermion Metals
We present a theory of the dynamic magnetic susceptibility of quantum spin
liquid. The obtained results are in good agreement with experimental facts
collected on herbertsmithite ZnCu3(OH)6Cl2 and on heavy-fermion metals, and
allow us to predict a new scaling in magnetic fields in the dynamic
susceptibility. Under the application of strong magnetic fields quantum spin
liquid becomes completely polarized. We show that this polarization can be
viewed as a manifestation of gapped excitations when investigating the
spin-lattice relaxation rate.Comment: 6 pages, 3 figures, minor improvements, published versio
Thermodynamic Properties of Kagome Lattice in ZnCu_3(OH)_6Cl_2 Herbertsmithite
Strongly correlated Fermi systems are among the most intriguing and
fundamental systems in physics, whose realization in some compounds is still to
be discovered. We show that herbertsmithite ZnCu_3(OH)_6Cl_2 can be viewed as a
strongly correlated Fermi system whose low temperature thermodynamic in
magnetic fields is defined by a quantum critical spin liquid. Our calculations
of its thermodynamic properties are in good agreement with recent experimental
facts and allow us to reveal their scaling behavior which strongly resembles
that observed in HF metals and 2D 3He.Comment: 4 pages, 6 figure
Low Threshold Parametric Decay Back Scattering Instability in Tokamak ECRH Experiments
The experimental conditions leading to substantial reduction of
backscattering decay instability threshold in ECRH experiments in toroidal
devices are analyzed. It is shown that drastic decrease of threshold is
provided by non monotonic behavior of plasma density in the vicinity of
magnetic island and poloidal magnetic field inhomogeneity making possible
localization of ion Bernstein decay waves. The corresponding ion Bernstein wave
gain and the parametric decay instability pump power threshold is calculated.Comment: 7 pages, 4 figure
General properties of phase diagrams of heavy-fermion metals
We study the temperature-magnetic field T-B phase diagrams of heavy fermion
(HF) metals, and show that at sufficiently high temperatures outside the
ordered phase the crossover temperature T*(B), regarded as the energy scale,
follows a linear B-dependence, crossing the origin of the T-B phase diagram.
This behavior of T*(B) constitutes the general property, and is formed by the
presence of fermion condensation quantum phase transition hidden within the
ordered phase. Our result is in good agreement with the experimental T-B phase
diagram of the HF metals YbRh2Si2, Yb(Rh{0.93}Co{0.07})2Si2, and
Yb(Rh{0.94}Ir{0.06})2Si2. To support our observations, we analyze the
isothermal magnetization M, and demonstrate that dM/dT exhibits a universal
temperature behavior over magnetic field scaling. The obtained results are in
good agreement with the corresponding data collected on YbRh2Si2 as a function
of magnetic field at different temperatures under hydrostatic pressure.Comment: 6 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1311.062
- …