78,500 research outputs found
Marginal Fermi liquid behavior from 2d Coulomb interaction
A full, nonperturbative renormalization group analysis of interacting
electrons in a graphite layer is performed, in order to investigate the
deviations from Fermi liquid theory that have been observed in the experimental
measures of a linear quasiparticle decay rate in graphite. The electrons are
coupled through Coulomb interactions, which remain unscreened due to the
semimetallic character of the layer. We show that the model flows towards the
noninteracting fixed-point for the whole range of couplings, with logarithmic
corrections which signal the marginal character of the interaction separating
Fermi liquid and non-Fermi liquid regimes.Comment: 7 pages, 2 Postscript figure
InAs/InP single quantum wire formation and emission at 1.5 microns
Isolated InAs/InP self-assembled quantum wires have been grown using in situ
accumulated stress measurements to adjust the optimal InAs thickness. Atomic
force microscopy imaging shows highly asymmetric nanostructures with average
length exceeding more than ten times their width. High resolution optical
investigation of as-grown samples reveals strong photoluminescence from
individual quantum wires at 1.5 microns. Additional sharp features are related
to monolayer fluctuations of the two dimensional InAs layer present during the
early stages of the quantum wire self-assembling process.Comment: 4 pages and 3 figures submitted to Applied Physics Letter
X-ray/gamma-ray flux correlations in the BL Lacs Mrk 421 and 501 using HAWC data
The HAWC gamma ray observatory is located at the Sierra Negra Volcano in
Puebla, Mexico, at an altitude of 4,100 meters. HAWC is a wide field of view
array of 300 water Cherenkov detectors that are continuously surveying ~ 2sr of
the sky, operating since March 2015. The large collected data sample allows
HAWC to perform an unbiased monitoring of the BL Lac Mrk 421. This is the
closest and brightest known extragalactic high-synchrotron-peaked BL Lac in the
gamma-ray/X- ray bands and is extensively monitored by the Large Area Telescope
(LAT) on-board the Fermi satellite, and the BAT and XRT instruments of the
Swift satellite. In this work, we use 25 months of HAWC data together with
Swift-XRT data to characterize potential correlations between both wavelengths.
This analysis shows that HAWC and Swift-XRT data are correlated even stronger
than expected for quasi-simultaneous observations.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017),
Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution
Reflection formulas for order derivatives of Bessel functions
From new integral representations of the -th derivative of Bessel
functions with respect to the order, we derive some reflection formulas for the
first and second order derivative of and % Y_{\nu
}\left( t\right) for integral order, and for the -th order derivative of
and for arbitrary real
order. As an application of the reflection formulas obtained for the first
order derivative, we extend some formulas given in the literature to negative
integral order. Also, as a by-product, we calculate an integral which does not
seem to be reported in the literature.Comment: arXiv admin note: text overlap with arXiv:1808.0560
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