3,804 research outputs found
Temperature dependence of spinon and holon excitations in one-dimensional Mott insulators
Motivated by the recent angle-resolved photoemission spectroscopy (ARPES)
measurements on one-dimensional Mott insulators, SrCuO and
NaVO, we examine the single-particle spectral weight
of the one-dimensional (1D) Hubbard model at half-filling. We are particularly
interested in the temperature dependence of the spinon and holon excitations.
For this reason, we have performed the dynamical density matrix renormalization
group and determinantal quantum Monte Carlo (QMC) calculations for the
single-particle spectral weight of the 1D Hubbard model. In the QMC data, the
spinon and holon branches become observable at temperatures where the
short-range antiferromagnetic correlations develop. At these temperatures, the
spinon branch grows rapidly. In the light of the numerical results, we discuss
the spinon and holon branches observed by the ARPES experiments on
SrCuO. These numerical results are also in agreement with the
temperature dependence of the ARPES results on NaVO.Comment: 8 pages, 8 figure
Gauge-mediated supersymmetry breaking with generalized messenger sector at LHC
We consider the generalized gauge mediated supersymmetry breaking (GMSB)
models with the messenger elds which do not form the complete multiplets of SU(5)
GUT symmetry. Such a situation may happen in the anomalous U(1) GUT scenario
because the mass spectrum of the superheavy particle does not respect SU(5) GUT
symmetry, although the success of the gauge coupling uni cation can be explained.
In this paper, we assume that one pair of the messenger elds gives the dominant
contribution, and the LHC signature for the two possible messengers, X + X and
Q + Q, are examined. We investigate the possibility to measure the deviation from
the usual GUT relation of the gaugino masses which is one of the most important
features of these scenarios.
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Joule heating generated by spin current through Josephson junctions
We theoretically study the spin-polarized current flowing through a Josephson
junction (JJ) in a spin injection device. When the spin-polarized current is
injected from a ferromagnet (FM) in a superconductor (SC), the charge current
is carried by the superconducting condensate (Cooper pairs), while the spin-up
and spin-down currents flow in the equal magnitude but in the opposite
direction in SC, because of no quasiparticle charge current in SC. This
indicates that not only the Josephson current but also the spin current flow
across JJ at zero bias voltage, thereby generating Joule heating by the spin
current. The result provides a new method for detecting the spin current by
measuring Joule heating at JJ.Comment: 3 pages, 2 figure
Mott Gap Excitations and Resonant Inelastic X-Ray Scattering in Doped Cuprates
Predictions are made for the momentum- and carrier-dependent degradation of
the Mott gap upon doping in high-Tc cuprates as would be observed in Cu K-edge
resonant inelastic x-ray scattering (RIXS). The two-dimensional Hubbard model
with second- and third-nearest-neighbor hopping terms has been studied by
numerical exact diagonalization. Special emphasis is placed on the
particle-hole asymmetry of the Mott gap excitations. We argue that the Mott gap
excitations observed by RIXS are significantly influenced by the interaction
between charge carriers and antiferromagnetic correlations.Comment: 4 pages, 4 figures, revised version; to be published in Phys. Rev.
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Gauge Coupling Unification in GUT with Anomalous U(1) Symmetry
We show that in the framework of grand unified theory (GUT) with anomalous
gauge symmetry, the success of the gauge coupling unification in the
minimal SU(5) GUT is naturally explained, even if the mass spectrum of
superheavy fields does not respect SU(5) symmetry. Because the unification
scale for most realizations of the theory becomes smaller than the usual GUT
scale, it suggests that the present level of experiments is close to that
sufficient to observe proton decay via dimension 6 operators, .Comment: 4 pages, RevTeX, to appear in Phys.Rev.Let
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