57 research outputs found
Electron cyclotron mass in undoped CdTe/CdMnTe quantum wells
Optically detected cyclotron resonance of two-dimensional electrons has been
studied in nominally undoped CdTe/(Cd,Mn)Te quantum wells. The enhancement of
carrier quantum confinement results in an increase of the electron cyclotron
mass from 0.099 to 0.112 with well width decreasing from 30 down to
3.6 nm. Model calculations of the electron effective mass have been performed
for this material system and good agreement with experimental data is achieved
for an electron-phonon coupling constant =0.32
Peculiarities of polyneuropathy in the peripheral t-cell lymphoma with cytostatics
This paper presents data on the occurrence and form of polyneuropathy in the peripheral T-cell lymphoma, and its main pathogenesis elements. Here the toxic effects of cytotoxic drugs and their role in the impairment of the nervous system have been describe
Entropy, Contact Interaction with Horizon and Dark Energy
We present some arguments suggesting that the mismatch between Bekenstein-
Hawking entropy and the entropy of entanglement for vector fields is due to the
same gauge configurations which saturate the contact term in topological
susceptibility in QCD. In both cases the extra term with a "wrong sign" is due
to distinct topological sectors in gauge theories. This extra term has
non-dispersive nature, can not be restored from conventional spectral function
through dispersion relations, and can not be associated with any physical
propagating degrees of freedom. We make few comments on some profound
consequences of our findings. In particular, we speculate that the source of
the observed dark energy may also be related to the same type of gauge
configurations which are responsible for the mismatch between black hole
entropy and the entropy of entanglement in the presence of causal horizon.Comment: final version to appear in Phys. Rev. D (2011
Magnetic monopoles, alive
We review recent developments in understanding the physics of the magnetic
monopoles in unbroken non-Abelian gauge theories. Since numerical data on the
monopoles are accumulated in lattice simulations, the continuum theory is
understood as the limiting case of the lattice formulation. In this review,
written for a memorial volume dedicated to the memory of Academician A.B.
Migdal, we emphasize physical effects related to the monopoles. In particular,
we discuss the monopole-antimonopole potential at short and larger distances as
well as a dual formulation of the gluodynamics, relevant to the physics of the
confinement.Comment: 24+1 pp., Latex2e, no figure
On the non-Abelian Stokes theorem for SU(2) gauge fields
We derive a version of non-Abelian Stokes theorem for SU(2) gauge fields in
which neither additional integration nor surface ordering are required. The
path ordering is eliminated by introducing the instantaneous color orientation
of the flux. We also derive the non-Abelian Stokes theorem on the lattice and
discuss various terms contributing to the trace of the Wilson loop.Comment: Latex2e, 0+14 pages, 3 figure
Microwave magnetoplasma resonances of two-dimensional electrons in MgZnO/ZnO heterojunctions
The plasma, magnetoplasma, and edge magnetoplasma excitations were investigated in two-dimensional electron systems hosted at the heterointerface of MgZnO/ZnO structures using optical detection of resonant microwave absorption. The magnetodispersion of the plasma excitations allowed the extraction of the electron effective mass. It was found to exhibit a surprisingly large dependence on the electron density, which is difficult to account for just from nonparabolicity effects
Quark-antiquark potential with retardation and radiative contributions and the heavy quarkonium mass spectra
The charmonium and bottomonium mass spectra are calculated with the
systematic account of all relativistic corrections of order v^2/c^2 and the
one-loop radiative corrections. Special attention is paid to the contribution
of the retardation effects to the spin-independent part of the quark-antiquark
potential, and a general approach to accounting for retardation effects in the
long-range (confining) part of the potential is presented. A good fit to
available experimental data on the mass spectra is obtained.Comment: 20 pages, revtex, 2 Postscript figure
First principles study of the origin and nature of ferromagnetism in (Ga,Mn)As
The properties of diluted GaMnAs are calculated for a wide range
of Mn concentrations within the local spin density approximation of density
functional theory. M\"ulliken population analyses and orbital-resolved
densities of states show that the configuration of Mn in GaAs is compatible
with either 3d or 3d, however the occupation is not integer due to the
large - hybridization between the Mn states and the valence band of
GaAs. The spin splitting of the conduction band of GaAs has a mean field-like
linear variation with the Mn concentration and indicates ferromagnetic coupling
with the Mn ions. In contrast the valence band is antiferromagnetically coupled
with the Mn impurities and the spin splitting is not linearly dependent on the
Mn concentration. This suggests that the mean field approximation breaks down
in the case of Mn-doped GaAs and corrections due to multiple scattering must be
considered. We calculate these corrections within a simple free electron model
and find good agreement with our {\it ab initio} results if a large exchange
constant (eV) is assumed.Comment: 15 pages, 14 figure
Effective String Theory of Vortices and Regge Trajectories
Starting from a field theory containing classical vortex solutions, we obtain
an effective string theory of these vortices as a path integral over the two
transverse degrees of freedom of the string. We carry out a semiclassical
expansion of this effective theory, and use it to obtain corrections to Regge
trajectories due to string fluctuations.Comment: 27 pages, revtex, 3 figures, corrected an error with the cutoff in
appendix E (was previously D), added more discussion of Fig. 3, moved some
material in section 9 to a new appendi
Diagonal deformations of thin center vortices and their stability in Yang-Mills theories
The importance of center vortices for the understanding of the confining
properties of SU(N) Yang-Mills theories is well established in the lattice.
However, in the continuum, there is a problem concerning the relevance of
center vortex backgrounds. They display the so called Savvidy-Nielsen-Olesen
instability, associated with a gyromagnetic ratio for the
off-diagonal gluons.
In this work, we initially consider the usual definition of a {\it thin}
center vortex and rewrite it in terms of a local color frame in SU(N)
Yang-Mills theories. Then, we define a thick center vortex as a diagonal
deformation of the thin object. Besides the usual thick background profile,
this deformation also contains a frame defect coupled with gyromagnetic ratio
, originated from the charged sector. As a consequence, the
analysis of stability is modified. In particular, we point out that the defect
should stabilize a vortex configuration formed by a pair of straight components
separated by an appropriate finite distance.Comment: 20 pages, LaTe
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