5,052 research outputs found
Deformation quantization of gerbes
This is the first in a series of articles devoted to deformation quantization
of gerbes. Here we give basic definitions and interpret deformations of a given
gerbe as Maurer-Cartan elements of a differential graded Lie algebra (DGLA). We
classify all deformations of a given gerbe on a symplectic manifold, as well as
provide a deformation-theoretic interpretation of the first Rozansky-Witten
class.Comment: Revised versio
A variant of the Mukai pairing via deformation quantization
We give a new method to prove a formula computing a variant of Caldararu's
Mukai pairing \cite{Cal1}. Our method is based on some important results in the
area of deformation quantization. In particular, part of the work of Kashiwara
and Schapira in \cite{KS} as well as an algebraic index theorem of Bressler,
Nest and Tsygan in \cite{BNT},\cite{BNT1} and \cite{BNT2} are used. It is hoped
that our method is useful for generalization to settings involving certain
singular varieties.Comment: 8 pages. Comments and suggestions welcom
Kikuchi ultrafast nanodiffraction in four-dimensional electron microscopy
Coherent atomic motions in materials can be revealed using time-resolved X-ray and electron Bragg diffraction. Because of the size
of the beam used, typically on the micron scale, the detection of
nanoscale propagating waves in extended structures hitherto has not
been reported. For elastic waves of complex motions, Bragg intensities
contain all polarizations and they are not straightforward to
disentangle. Here, we introduce Kikuchi diffraction dynamics, using
convergent-beam geometry in an ultrafast electron microscope, to
selectively probe propagating transverse elastic waves with nanoscale
resolution. It is shown that Kikuchi band shifts, which are sensitive
only to the tilting of atomic planes, reveal the resonance
oscillations, unit cell angular amplitudes, and the polarization
directions. For silicon, the observed wave packet temporal envelope (resonance frequency of 33 GHz), the out-of-phase temporal behavior of
Kikuchi's edges, and the magnitude of angular amplitude (0.3 mrad) and
polarization [011] elucidate the nature of the motion:
one that preserves the mass density (i.e., no compression or expansion)
but leads to sliding of planes in the antisymmetric shear eigenmode of
the elastic waveguide. As such, the method of Kikuchi diffraction
dynamics, which is unique to electron imaging, can be used to
characterize the atomic motions of propagating waves and their
interactions with interfaces, defects, and grain boundaries at the
nanoscale
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