7,966 research outputs found
Torus actions of complexity one in non-general position
Let the compact torus act on a smooth compact manifold
effectively with nonempty finite set of fixed points. We pose the question:
what can be said about the orbit space if the action is
cohomologically equivariantly formal (which essentially means that
). It happens that homology of the orbit space
can be arbitrary in degrees and higher. For any finite simplicial complex
we construct an equivariantly formal manifold such that
is homotopy equivalent to . The constructed
manifold is the total space of the projective line bundle over the
permutohedral variety hence the action on is Hamiltonian and
cohomologically equivariantly formal. We introduce the notion of the action in
-general position and prove that, for any simplicial complex , there
exists an equivariantly formal action of complexity one in -general position
such that its orbit space is homotopy equivalent to .Comment: 14 page
Fingerprints of angulon instabilities in the spectra of matrix-isolated molecules
The formation of vortices is usually considered to be the main mechanism of
angular momentum disposal in superfluids. Recently, it was predicted that a
superfluid can acquire angular momentum via an alternative, microscopic route
-- namely, through interaction with rotating impurities, forming so-called
`angulon quasiparticles' [Phys. Rev. Lett. 114, 203001 (2015)]. The angulon
instabilities correspond to transfer of a small number of angular momentum
quanta from the impurity to the superfluid, as opposed to vortex instabilities,
where angular momentum is quantized in units of per atom. Furthermore,
since conventional impurities (such as molecules) represent three-dimensional
(3D) rotors, the angular momentum transferred is intrinsically 3D as well, as
opposed to a merely planar rotation which is inherent to vortices. Herein we
show that the angulon theory can explain the anomalous broadening of the
spectroscopic lines observed for CH and NH molecules in superfluid
helium nanodroplets, thereby providing a fingerprint of the emerging angulon
instabilities in experiment.Comment: 7 pages + supplemen
Large non-adiabatic hole polarons and matrix element effects in the angle-resolved photoemission spectroscopy of dielectric cuprates
It has been made an extention of the conventional theory based on the
assumption of the well isolated Zhang-Rice singlet to be a first
electron-removal state in dielectric copper oxide. One assumes the photohole
has been localised on either small (pseudo)Jahn-Teller polaron or large
non-adiabatic polaron enclosed one or four to five centers,
respectively, with active one-center valent
manifold. In the framework of the cluster model we have performed a model
microscopic calculation of the -dependence of the matrix element
effects and photon polarization effects for the angle-resolved photoemission in
dielectric cuprate like . We show that effects like the
''remnant Fermi surface'' detected in ARPES experiment for
may be, in fact, a reflection of the matrix element
effects, not a reflection of the original band-structure Fermi surface, or the
strong antiferromagnetic correlations. The measured dispersion-like features in
the low-energy part of the ARPES spectra may be a manifestation of the complex
momentum-dependent spectral line-shape of the large PJT polaron response, not
the dispersion of the well-isolated Zhang-Rice singlet in antiferromagnetic
matrix.Comment: 16 pages, TeX, 9 eps figures adde
Numerical simulation of strain localization in multi-pass welded joints with account of residual stresses
A two-dimensional elastic-plastic problem was solved to obtain estimation of a residual thermal stresses during cooling of the weld. Quasi-static processes of strain localization in the heat-affected zone were investigated both for compression and tension taking into account influence of residual stress concentrators and heterogeneity of mechanical characteristics of welded materials
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