3,113 research outputs found
Residues and Topological Yang-Mills Theory in Two Dimensions
A residue formula which evaluates any correlation function of topological
Yang-Mills theory with arbitrary magnetic flux insertion in two
dimensions are obtained. Deformations of the system by two form operators are
investigated in some detail. The method of the diagonalization of a matrix
valued field turns out to be useful to compute various physical quantities. As
an application we find the operator that contracts a handle of a Riemann
surface and a genus recursion relation.Comment: 23 pages, some references added, to appear in Rev.Math.Phy
van der Waals Bonded Co/h-BN Contacts to Ultrathin Black Phosphorus Devices
Due to the chemical inertness of 2D hexagonal-Boron Nitride (h-BN), few
atomic-layer h-BN is often used to encapsulate air-sensitive 2D crystals such
as Black Phosphorus (BP). However, the effects of h-BN on Schottky barrier
height, doping and contact resistance are not well known. Here, we investigate
these effects by fabricating h-BN encapsulated BP transistors with cobalt (Co)
contacts. In sharp contrast to directly Co contacted p-type BP devices, we
observe strong n-type conduction upon insertion of the h-BN at the Co/BP
interface. First principles calculations show that this difference arises from
the much larger interface dipole at the Co/h-BN interface compared to the Co/BP
interface, which reduces the work function of the Co/h-BN contact. The Co/h-BN
contacts exhibit low contact resistances (~ 4.5 k-ohm), and are Schottky
barrier free. This allows us to probe high electron mobilities (4,200 cm2/Vs)
and observe insulator-metal transitions even under two-terminal measurement
geometry
Hypergeometric solutions to the q-Painlev\'e equation of type
We consider the q-Painlev\'e equation of type (a version of
q-Painlev\'e V equation) and construct a family of solutions expressible in
terms of certain basic hypergeometric series. We also present the determinant
formula for the solutions.Comment: 16 pages, IOP styl
Why can they fly and swim? Dynamic similarity between flight and swimming in Rhinoceros auklets
第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月26日(月) 国立極地研究所 3階ラウン
Local moment formation in quantum point contacts
Spin-density-functional theory of quantum point contacts (QPCs) reveals the
formation of a local moment with a net of one electron spin in the vicinity of
the point contact - supporting the recent report of a Kondo effect in a QPC.
The hybridization of the local moment to the leads decreases as the QPC becomes
longer, while the onsite Coulomb-interaction energy remains almost constant.Comment: 10 pages, 3 figures, accepted for publication in Physical Review
Letter
Discovery of X rays from Class 0 protostar candidates in OMC-3
We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with
the Chandra X-ray Observatory (CXO). The northern part of OMC-3 is found to be
particularly rich in new X-ray features; four hard X-ray sources are located in
and along the filament of cloud cores. Two sources coincide positionally with
the sub- dust condensations of MMS 2 and 3 or an outflow radio source
VLA 1, which are in a very early phase of star formation. The X-ray spectra of
these sources show an absorption column of (1-3) x 10^23 H cm-2. Assuming a
moderate temperature plasma, the X-ray luminosity in the 0.5-10 keV band is
estimated to be ~10^30 erg s^-1 at a distance of 450 pc. From the large
absorption, positional coincidence and moderate luminosity, we infer that the
hard X-rays are coming from very young stellar objects embedded in the
molecular cloud cores. We found another hard X-ray source near the edge of the
dust filament. The extremely high absorption of 3 x 10^23 H cm^-2 indicates
that the source must be surrounded by dense gas, suggesting that it is either a
YSO in an early accretion phase or a Type II AGN (e.g. a Seyfert 2), although
no counterpart is found at any other wavelength. In contrast to the hard X-ray
sources, soft X-ray sources are found spread around the dust filaments, most of
which are identified with IR sources in the T Tauri phase.Comment: 9 pages, To be appeared in ApJ v554 n2 Jun 20, 2001 issue, related
press release is available at http://science.psu.edu/alert/Tsuboi11-2000.htm,
Figure 1 and figure 2 with the best resolution is available at
ftp.astro.psu.edu/pub/tsuboi/OMC/010205
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