7,910 research outputs found
Higher spins on AdS from the worldsheet
It was recently shown that the CFT dual of string theory on , the symmetric orbifold of , contains a
closed higher spin subsector. Via holography, this makes precise the sense in
which tensionless string theory on this background contains a Vasiliev higher
spin theory. In this paper we study this phenomenon directly from the
worldsheet. Using the WZW description of the background with pure NS-NS flux,
we identify the states that make up the leading Regge trajectory and show that
they fit into the even spin Vasiliev higher spin theory. We also
show that these higher spin states do not become massless, except for the
somewhat singular case of level where the theory contains a stringy tower
of massless higher spin fields coming from the long string sector.Comment: 29+8 pages, 3 figure
Ultrafast Dynamic Metallization of Dielectric Nanofilms by Strong Single-Cycle Optical Fields
We predict a dynamic metallization effect where an ultrafast (single-cycle)
optical pulse with a field less or on the order of 1 V/Angstrom causes
plasmonic metal-like behavior of a dielectric film with a few-nm thickness.
This manifests itself in plasmonic oscillations of polarization and a
significant population of the conduction band evolving on a femtosecond time
scale. These phenomena are due a combination of both adiabatic (reversible) and
diabatic (for practical purposes irreversible) pathways.Comment: 4 pages, 4 figure
Fermi-liquid effects in the Fulde-Ferrell-Larkin-Ovchinnikov state of two-dimensional d-wave superconductors
We study the effects of Fermi-liquid interactions on quasi-two-dimensional
d-wave superconductors in a magnetic field. The phase diagram of the
superconducting state, including the periodic Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) state in high magnetic fields, is discussed for different strengths of
quasiparticle many-body interactions within Landau's theory of Fermi liquids.
Decreasing the Fermi-liquid parameter causes the magnetic spin
susceptibility to increase, which in turn leads to a reduction of the FFLO
phase. It is shown that a negative results in a first-order phase
transition from the normal to the uniform superconducting state in a finite
temperature interval. Finally, we discuss the thermodynamic implications of a
first-order phase transition for CeCoIn.Comment: published version; removed direct comparison with experiment for the
upper critical field, as required by the referee
Spontaneous interlayer coherence in bilayer Kondo systems
Bilayer Kondo systems present interesting models to illustrate the
competition between the Kondo effect and intermoment exchange. Such bilayers
can exhibit two sharply distinct Fermi liquid phases which are distinguished by
whether or not the local moments participate in the Fermi sea. We study these
phases and the evolution from one to the other upon changing Kondo coupling. We
argue that an ordered state with spontaneous interlayer phase coherence
generically intervenes between the two Fermi liquids. Such a condensate phase
breaks a U(1) symmetry and is bounded by a finite-temperature
Kosterlitz-Thouless transition. Based on general arguments and mean-field
calculations we investigate the phase diagram and associated quantum phase
transitions.Comment: 4 pages, 3 figs, (v2) misprints in eqs corrected, final version as
publishe
Proposal for a Precision Measurement of |Vub|
A new method for a precision measurement of the CKM matrix element |Vub| is
discussed, which combines good theoretical control with high efficiency and a
powerful discrimination against charm background. The resulting combined
theoretical uncertainty on |Vub| is estimated to be 10%.Comment: 4 pages, 2 figures, RevTe
Neutron star properties in the quark-meson coupling model
The effects of internal quark structure of baryons on the composition and structure of neutron star matter with hyperons are investigated in the quark- meson coupling (QMC) model. The QMC model is based on mean-field description of nonoverlapping spherical bags bound by self-consistent exchange of scalar and vector mesons. The predictions of this model are compared with quantum hadrodynamic (QHD) model calibrated to reproduce identical nuclear matter saturation properties. By employing a density dependent bag constant through direct coupling to the scalar field, the QMC model is found to exhibit identical properties as QHD near saturation density. Furthermore, this modified QMC model provides well-behaved and continuous solutions at high densities relevant to the core of neutron stars. Two additional strange mesons are introduced which couple only to the strange quark in the QMC model and to the hyperons in the QHD model. The constitution and structure of stars with hyperons in the QMC and QHD models reveal interesting di erences. This suggests the importance of quark structure e ects in the baryons at high densities. PACS number(s): 26.60.+c, 21.65.+f, 12.39.Ba, 24.85.+
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