14,110 research outputs found
Third order differential subordination and superordination results for analytic functions involving the Srivastava-Attiya operator
In this article, by making use of the linear operator introduced and studied
by Srivastava and Attiya \cite{srivastava1}, suitable classes of admissible
functions are investigated and the dual properties of the third-order
differential subordinations are presented. As a consequence, various
sandwich-type theorems are established for a class of univalent analytic
functions involving the celebrated Srivastava-Attiya transform. Relevant
connections of the new results are pointed out.Comment: 16. arXiv admin note: substantial text overlap with arXiv:1809.0651
Laser-Induced Above-Bandgap Transparency in GaAs
We report the observation of large () laser-induced above-bandgap
transparency in GaAs at room temperature. The induced transparency is present
only during the pulse width of the driving midinfrard laser pulses and its
spectral shape is consistent with a laser-induced blue shift of the band edge.
Our simulations based on the dynamic Franz-Keldysh effect reproduce the salient
features of the experimental results, demonstrating in particular that the
amount of the band edge shift is approximately given by the ponderomtive
potential.Comment: 4 pages, 4 figure
Light-Front-Quantized QCD in Covariant Gauge
The light-front (LF) canonical quantization of quantum chromodynamics in
covariant gauge is discussed. The Dirac procedure is used to eliminate the
constraints in the gauge-fixed front form theory quantum action and to
construct the LF Hamiltonian formulation. The physical degrees of freedom
emerge naturally. The propagator of the dynamical part of the free
fermionic propagator in the LF quantized field theory is shown to be causal and
not to contain instantaneous terms. Since the relevant propagators in the
covariant gauge formulation are causal, rotational invariance---including the
Coulomb potential in the static limit---can be recovered, avoiding the
difficulties encountered in light-cone gauge. The Wick rotation may also be
performed allowing the conversion of momentum space integrals into Euclidean
space forms. Some explicit computations are done in quantum electrodynamics to
illustrate the equivalence of front form theory with the conventional covariant
formulation. LF quantization thus provides a consistent formulation of gauge
theory, despite the fact that the hyperplanes used to impose
boundary conditions constitute characteristic surfaces of a hyperbolic partial
differential equation.Comment: LaTex, 16 page
Optical Phonon Lineshapes and Transport in Metallic Carbon Nanotubes under High Bias Voltage
We calculate the current-voltage characteristic of metallic nanotubes at high
bias voltage showing that a bottleneck exists for short nanotubes in contrast
to large ones. We attribute this to a redistribution of lower-lying acoustic
phonons caused by phonon-phonon scattering with hot optical phonons. The
current-voltage characteristic and the electron and phonon distribution
functions are derived analytically, and serve to obtain in a self-contained way
the frequency shift and line broadening of the zone center optical phonons due
to the electron-phonon coupling at high bias. We obtain a positive frequency
shift from the zero bias shift and no broadening of the optical phonon mode at
very high voltages, in agreement with recent experiments.Comment: 16 pages, 8 figures, minor changes, pusblished in PR
Bremsstrahlung from an Equilibrating Quark-Gluon Plasma
The photon production rate from a chemically equilibrating quark-gluon plasma
likely to be produced at RHIC (BNL) and LHC (CERN) energies is estimated taking
into account bremsstrahlung. The plasma is assumed to be in local thermal
equilibrium, but with a phase space distribution that deviates from the Fermi
or Bose distribution by space-time dependent factors (fugacities). The photon
spectrum is obtained by integrating the photon rate over the space-time history
of the plasma, adopting a boost invariant cylindrically symmetric transverse
expansion of the system with different nuclear profile functions. Initial
conditions obtained from a self-screened parton cascade calculation and, for
comparison, from the HIJING model are used. Compared to an equilibrated plasma
at the same initial energy density, taken from the self-screened parton
cascade, a moderate suppression of the photon yield by a factor of one to five
depending on the collision energy and the photon momentum is observed. The
individual contributions to the photon production, however, are completely
different in the both scenarios.Comment: 14 pages, 4 figures, shortened version to be published in Phys. Rev.
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