56 research outputs found
Localized Tachyons and the Quantum McKay Correspondence
The condensation of closed string tachyons localized at the fixed point of a
C^d/\Gamma orbifold can be studied in the framework of renormalization group
flow in a gauged linear sigma model. The evolution of the Higgs branch along
the flow describes a resolution of singularities via the process of tachyon
condensation. The study of the fate of D-branes in this process has lead to a
notion of a ``quantum McKay correspondence.'' This is a hypothetical
correspondence between fractional branes in an orbifold singularity in the
ultraviolet with the Coulomb and Higgs branch branes in the infrared. In this
paper we present some nontrivial evidence for this correspondence in the case
C^2/Z_n by relating the intersection form of fractional branes to that of
``Higgs branch branes,'' the latter being branes which wrap nontrivial cycles
in the resolved space.Comment: 25 pages; harvma
Chronon corrections to the Dirac equation
The Dirac equation is not semisimple. We therefore regard it as a contraction
of a simpler decontracted theory. The decontracted theory is necessarily purely
algebraic and non-local. In one simple model the algebra is a Clifford algebra
with 6N generators. The quantum imaginary is the contraction of a
dynamical variable whose back-reaction provides the Dirac mass. The simplified
Dirac equation is exactly Lorentz invariant but its symmetry group is SO(3,3),
a decontraction of the Poincare group, and it has a slight but fundamental
non-locality beyond that of the usual Dirac equation. On operational grounds
the non-locality is ~10^{-25} sec in size and the associated mass is about the
Higgs mass.
There is a non-standard small but unique spin-orbit coupling ~1/N, whose
observation would be some evidence for the simpler theory. All the fields of
the Standard Model call for similar non-local simplification.Comment: 14 pages, no figures. Accepted to J.Math.Phy
Non-Equilibrium Scaling Analysis of the Kondo Model with Voltage Bias
The quintessential description of Kondo physics in equilibrium is obtained
within a scaling picture that shows the buildup of Kondo screening at low
temperature. For the non-equilibrium Kondo model with a voltage bias the key
new feature are decoherence effects due to the current across the impurity. In
the present paper we show how one can develop a consistent framework for
studying the non-equilibrium Kondo model within a scaling picture of
infinitesimal unitary transformations (flow equations). Decoherence effects
appear naturally in third order of the beta-function and dominate the
Hamiltonian flow for sufficiently large voltage bias. We work out the spin
dynamics in non-equilibrium and compare it with finite temperature equilibrium
results. In particular, we report on the behavior of the static spin
susceptibility including leading logarithmic corrections and compare it with
the celebrated equilibrium result as a function of temperature.Comment: 22 pages, 15 figure
Modulation by Phenolic Compounds Provides Novel Insight into the Mechanisms of TRPA1 Activation
status: publishe
TRPA1 activation by phenol derivatives reveals novel insights into the channel gating mechanisms
status: publishe
Bimodal action of menthol on the transient receptor potential channel TRPA1
TRPA1 is a calcium-permeable nonselective cation transient receptor potential (TRP) channel that functions as an excitatory ionotropic receptor in nociceptive neurons. TRPA1 is robustly activated by pungent substances in mustard oil, cinnamon, and garlic and mediates the inflammatory actions of environmental irritants and proalgesic agents. Here, we demonstrate a bimodal sensitivity of TRPA1 to menthol, a widely used cooling agent and known activator of the related cold receptor TRPM8. In whole-cell and single-channel recordings of heterologously expressed TRPA1, submicromolar to low-micromolar concentrations of menthol cause channel activation, whereas higher concentrations lead to a reversible channel block. In addition, we provide evidence for TRPA1-mediated menthol responses in mustard oil-sensitive trigeminal ganglion neurons. Our data indicate that TRPA1 is a highly sensitive menthol receptor that very likely contributes to the diverse psychophysical sensations after topical application of menthol to the skin or mucous membranes of the oral and nasal cavities.status: publishe
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