Surprising relations between parametric level correlations and fidelity decay

Unexpected relations between fidelity decay and cross form--factor, i.e., parametric level correlations in the time domain are found both by a heuristic argument and by comparing exact results, using supersymmetry techniques, in the framework of random matrix theory. A power law decay near Heisenberg time, as a function of the relevant parameter, is shown to be at the root of revivals recently discovered for fidelity decay. For cross form--factors the revivals are illustrated by a numerical study of a multiply kicked Ising spin chain.Comment: 4 pages 3 figure

A trivial observation on time reversal in random matrix theory

It is commonly thought that a state-dependent quantity, after being averaged over a classical ensemble of random Hamiltonians, will always become independent of the state. We point out that this is in general incorrect: if the ensemble of Hamiltonians is time reversal invariant, and the quantity involves the state in higher than bilinear order, then we show that the quantity is only a constant over the orbits of the invariance group on the Hilbert space. Examples include fidelity and decoherence in appropriate models.Comment: 7 pages 3 figure

Nonperturbative Effects in Quarkonia Associated with Large Orders in Perturbation Theory

We show that the perturbation series for quarkonia energies diverges at large orders. This results in a perturbative ambiguity in the energy that scales as e^(-1/a*Lambda) where a is the Bohr radius of quarkonium and Lambda is the QCD scale parameter. This ambiguity is associated with a nonperturbative contribution to the energy from distances of order 1/Lambda and greater. This contribution is separate from that of the gluon condensate.Comment: 6 pages, 2 figure

A Herschel [C II] Galactic plane survey II: CO-dark H2 in clouds

ABRIDGED: Context: HI and CO large scale surveys of the Milky Way trace the diffuse atomic clouds and the dense shielded regions of molecular hydrogen clouds. However, until recently, we have not had spectrally resolved C+ surveys to characterize the photon dominated interstellar medium, including, the H2 gas without C, the CO-dark H2, in a large sample of clouds. Aims: To use a sparse Galactic plane survey of the 1.9 THz [C II] spectral line from the Herschel Open Time Key Programme, Galactic Observations of Terahertz C+ (GOT C+), to characterize the H2 gas without CO in a statistically significant sample of clouds. Methods: We identify individual clouds in the inner Galaxy by fitting [CII] and CO isotopologue spectra along each line of sight. We combine these with HI spectra, along with excitation models and cloud models of C+, to determine the column densities and fractional mass of CO-dark H2 clouds. Results: We identify 1804 narrow velocity [CII] interstellar cloud components in different categories. About 840 are diffuse molecular clouds with no CO, 510 are transition clouds containing [CII] and 12CO, but no 13CO, and the remainder are dense molecular clouds containing 13CO emission. The CO-dark H2 clouds are concentrated between Galactic radii 3.5 to 7.5 kpc and the column density of the CO-dark H2 layer varies significantly from cloud-to-cloud with an average 9X10^(20) cm-2. These clouds contain a significant fraction of CO-dark H2 mass, varying from ~75% for diffuse molecular clouds to ~20% for dense molecular clouds. Conclusions: We find a significant fraction of the warm molecular ISM gas is invisible in HI and CO, but is detected in [CII]. The fraction of CO-dark H2 is greatest in the diffuse clouds and decreases with increasing total column density, and is lowest in the massive clouds.Comment: 21 pages, 19 figures, accepted for publication in A&A (2014

The infrared behaviour of the static potential in perturbative QCD

The definition of the quark-antiquark static potential is given within an effective field theory framework. The leading infrared divergences of the static singlet potential in perturbation theory are explicitly calculated.Comment: 4 pages, 2 postscript figures, uses revtex.st

Drug-like analogues of the parasitic worm-derived immunomodulator ES-62 are therapeutic in the MRL/Lpr model of systemic lupus erythematosus

Introduction ES-62, a phosphorylcholine (PC)-containing immunomodulator secreted by the parasitic worm Acanthocheilonema viteae, protects against nephritis in the MRL/Lpr mouse model of systemic lupus erythematosus (SLE). However, ES-62 is not suitable for development as a therapy and thus we have designed drug-like small molecule analogues (SMAs) based around its active PC-moiety. To provide proof of concept that ES-62-based SMAs exhibit therapeutic potential in SLE, we have investigated the capacity of two SMAs to protect against nephritis when administered to MRL/Lpr mice after onset of kidney damage. Methods SMAs 11a and 12b were evaluated for their ability to suppress antinuclear antibody (ANA) generation and consequent kidney pathology in MRL/Lpr mice when administered after the onset of proteinuria. Results SMAs 11a and 12b suppressed development of ANA and proteinuria. Protection reflected downregulation of MyD88 expression by kidney cells and this was associated with reduced production of IL-6, a cytokine that exhibits promise as a therapeutic target for this condition. Conclusions SMAs 11a and 12b provide proof of principle that synthetic compounds based on the safe immunomodulatory mechanisms of parasitic worms can exhibit therapeutic potential as a novel class of drugs for SLE, a disease for which current therapies remain inadequate