262 research outputs found
Hecke algebras of finite type are cellular
Let \cH be the one-parameter Hecke algebra associated to a finite Weyl
group , defined over a ground ring in which ``bad'' primes for are
invertible. Using deep properties of the Kazhdan--Lusztig basis of \cH and
Lusztig's \ba-function, we show that \cH has a natural cellular structure
in the sense of Graham and Lehrer. Thus, we obtain a general theory of ``Specht
modules'' for Hecke algebras of finite type. Previously, a general cellular
structure was only known to exist in types and .Comment: 14 pages; added reference
Hecke algebras with unequal parameters and Vogan's left cell invariants
In 1979, Vogan introduced a generalised -invariant for characterising
primitive ideals in enveloping algebras. Via a known dictionary this translates
to an invariant of left cells in the sense of Kazhdan and Lusztig. Although it
is not a complete invariant, it is extremely useful in describing left cells.
Here, we propose a general framework for defining such invariants which also
applies to Hecke algebras with unequal parameters.Comment: 15 pages. arXiv admin note: substantial text overlap with
arXiv:1405.573
Affine cellularity of affine Hecke algebras of rank two
We show that affine Hecke algebras of rank two with generic parameters are
affine cellular in the sense of Koenig-Xi.Comment: 24 pages, 4 figures and 14 tables. New version: added references,
corrected typos. Final versio
On Kazhdan-Lusztig cells in type B
32 pagesWe prove that, for any choice of parameters, the Kazhdan-Lusztig cells of a Weyl group of type are unions of combinatorial cells (defined using the domino insertion algorithm)
Affine Deligne-Lusztig varieties in affine flag varieties
This paper studies affine Deligne-Lusztig varieties in the affine flag
manifold of a split group. Among other things, it proves emptiness for certain
of these varieties, relates some of them to those for Levi subgroups, extends
previous conjectures concerning their dimensions, and generalizes the superset
method.Comment: 44 pages, 4 figures. Minor changes to font, references, and
acknowledgments. Improved introduction, other improvements in exposition, and
two new figures added, for a total of
X-ray absorption spectroscopy on layered cobaltates Na_xCoO_2
Measurements of polarization and temperature dependent soft x-ray absorption
have been performed on Na_xCoO_2 single crystals with x=0.4 and x=0.6. They
show a deviation of the local trigonal symmetry of the CoO_6 octahedra, which
is temperature independent in a temperature range between 25 K and 372 K. This
deviation was found to be different for Co^{3+} and Co^{4+} sites. With the
help of a cluster calculation we are able to interpret the Co L_{23}-edge
absorption spectrum and find a doping dependent energy splitting between the
t_{2g} and the e_g levels (10Dq) in Na_xCoO_2.Comment: 7 pages, 8 figure
Temperature-driven reorganization of electronic order in CsVSb
We report a temperature dependent x-ray diffraction study of the electronic
ordering instabilities in the kagome material CsVSb. Our measurements
between 10 K and 120 K reveal an unexpected reorganization of the
three-dimensional electronic order in the bulk of CsVSb: At 10 K, a
2x2x2 superstructure modulation due to electronic order is observed, which upon
warming changes to a 2x2x4 superstructure at 60 K. The electronic order-order
transition discovered here involves a change in the stacking of electronically
ordered VSb-layers and agrees perfectly with anomalies previously
observed in magneto-transport measurements. This implies that the temperature
dependent three-dimensional electronic order plays a decisive role for
transport properties, which are related to the Berry-curvature of the V-bands.
Our data also show that the bulk electronic order in CsVSb breaks the
6-fold rotational symmetry of the underlying lattice structure.Comment: 5 pages, 3 figure
Effect of Zn and Ni impurities on the quasiparticle renormalization in Bi-2212
The Cu substitution by Zn and Ni impurities and its influence on the mass
renormalization effects in angle resolved photoelectron spectra (ARPES) of
Bi-2212 is addressed. We show that the nonmagnetic Zn atoms have much stronger
effect both in nodal and antinodal parts of the Brillouin zone than magnetic
Ni. The observed changes are consistent with the behaviour of the spin
resonance mode as seen by inelastic neutron scattering in YBCO. This strongly
suggests that the "peak-dip-hump" and the "kink" in ARPES on the one side and
neutron resonance on the other are closely related features.Comment: 4 pages, 3 figure
Constituents of the "kink" in high-Tc cuprates
Applying the Kramers-Kronig consistent procedure, developed earlier, we
investigate in details the formation of the quasiparticle spectrum along the
nodal direction of high-Tc cuprates. The heavily discussed "70 meV kink" on the
renormalized dispersion exhibits a strong temperature and doping dependence
when purified from structural effects. This dependence is well understood in
terms of fermionic and bosonic constituents of the self-energy. The latter
follows the evolution of the spin-fluctuation spectrum, emerging below T* and
sharpening below Tc, and is the main responsible for the formation of the kink
in question.Comment: revte
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