CP-Violation in the Production of Tau-Leptons at TESLA with Beam Polarization

We study the prospects of discovering CP-violation in the production of tau-leptons in the reaction {e+e- --> tau+tau- at TESLA, an e+e- linear collider with center-of-mass energies of 500 or even 800 GeV. Non-vanishing expectation values of certain correlations between the momenta of the decay products of the two tau leptons would signalthe presence of CP-violation beyond the standard model. We study how longitudinal beam polarization of the electron and positron beams will enhance these correlations. We find that T-odd and T-even vector correlations are well suited for the measurements of the real and imaginary parts of the electric dipole form factors. We expect measurements of the real part with a precision of roughly 10^-20 ecm and of the imaginary part of 10^-17 ecm. This compares well with the size of the expected effects in many extensions of the standard model

Majorana Fermions in Strongly Interacting Helical Liquids

Majorana fermions were proposed to occur at edges and interfaces of gapped one-dimensional systems where phases with different topological character meet due to an interplay of spin-orbit coupling, proximity-induced superconductivity and external magnetic fields. Here we investigate the effect of strong particle interactions, and show that the helical liquid offers a mechanism that protects the very existence of Majorana edge states: whereas moderate interactions close the proximity gap which supports the edge states, in helical liquids the gap re-opens due to two-particle processes. However, gapless fermionic excitations occur at spatial proximity to the Majorana states at interfaces and may jeopardize their long term Majorana coherence.Comment: 7 pages, 4 figure

SVM-based texture classification in optical coherence tomography

This paper describes a new method for automated texture classification for glaucoma detection using high resolution retinal Optical Coherence Tomography (OCT). OCT is a non-invasive technique that produces cross-sectional imagery of ocular tissue. Here, we exploit information from OCT im-ages, specifically the inner retinal layer thickness and speckle patterns, to detect glaucoma. The proposed method relies on support vector machines (SVM), while principal component analysis (PCA) is also employed to improve classification performance. Results show that texture features can improve classification accuracy over what is achieved using only layer thickness as existing methods currently do. Index Terms — classification, support vector machine, optical coherence tomography, texture 1

Test of the isotropy of the speed of light using a continuously rotating optical resonator

We report on a test of Lorentz invariance performed by comparing the resonance frequencies of one stationary optical resonator and one continuously rotating on a precision air bearing turntable. Special attention is paid to the control of rotation induced systematic effects. Within the photon sector of the Standard Model Extension, we obtain improved limits on combinations of 8 parameters at a level of a few parts in $10^{-16}$. For the previously least well known parameter we find $\tilde \kappa_{e-}^{ZZ} =(-1.9 \pm 5.2)\times 10^{-15}$. Within the Robertson-Mansouri-Sexl test theory, our measurement restricts the isotropy violation parameter $\beta -\delta -\frac 12$ to $(-2.1\pm 1.9)\times 10^{-10}$, corresponding to an eightfold improvement with respect to previous non-rotating measurements.Comment: 4 pages, 3 figures, to appear in Phys. Rev. Let

Quantum Seismology

We propose a quantum mechanical method of detecting weak vibrational disturbances inspired by the protocol of entanglement farming. We consider a setup where pairs of atoms in their ground state are successively sent through an optical cavity. It is known that in this way it is possible to drive that cavity toward a stable fixed-point state. Here we study how that fixed-point state depends on the time interval between pairs of atoms and on the distance between the cavity's mirrors. Taking advantage of an extremely precise resonance effect, we find that there are special values of these parameters where the fixed-point state is highly sensitive to perturbations, even harmonic vibrations with frequencies several orders of magnitude below the cavity's natural frequency. We propose that this sensitivity may be useful for high precision metrology.Comment: 10 pages, 5 figures. RevTeX 4.

Neutrino and axion bounds from the globular cluster M5 (NGC 5904)

The red-giant branch (RGB) in globular clusters is extended to larger brightness if the degenerate helium core loses too much energy in "dark channels." Based on a large set of archival observations, we provide high-precision photometry for the Galactic globular cluster M5 (NGC 5904), allowing for a detailed comparison between the observed tip of the RGB with predictions based on contemporary stellar evolution theory. In particular, we derive 95% confidence limits of $g_{ae}<4.3\times10^{-13}$ on the axion-electron coupling and $\mu_\nu<4.5\times10^{-12}\,\mu_{\rm B}$ (Bohr magneton $\mu_{\rm B}=e/2m_e$) on a neutrino dipole moment, based on a detailed analysis of statistical and systematic uncertainties. The cluster distance is the single largest source of uncertainty and can be improved in the future.Comment: 5 pages, 2 figures, accepted for publication in Physical Review Letter

Exponential Decay Lifetimes of Excitons in Individual Single-Walled Carbon Nanotubes

The dynamics of excitons in individual semiconducting single-walled carbon nanotubes was studied using time-resolved photoluminescence (PL) spectroscopy. The PL decay from tubes of the same (n,m) type was found to be monoexponential, however, with lifetimes varying between less than 20 and 200 ps from tube to tube. Competition of nonradiative decay of excitons is facilitated by a thermally activated process, most likely a transition to a low-lying optically inactive trap state that is promoted by a low-frequency phonon mode

Explanation for Anomalous Shock Temperatures Measured by Neutron Resonance Spectroscopy

Neutron resonance spectrometry (NRS) has been used to measure the temperature inside Mo samples during shock loading. The temperatures obtained were significantly higher than predicted assuming ideal hydrodynamic loading. The effect of plastic flow and non-ideal projectile behavior were assessed. Plastic flow was calculated self-consistently with the shock jump conditions: this is necessary for a rigorous estimate of the locus of shock states accessible. Plastic flow was estimated to contribute a temperature rise of 53K compared with hydrodynamic flow. Simulations were performed of the operation of the explosively-driven projectile system used to induce the shock in the Mo sample. The simulations predicted that the projectile was significantly curved on impact, and still accelerating. The resulting spatial variations in load, including radial components of velocity, were predicted to increase the apparent temperature that would be deduced from the width of the neutron resonance by 160K. These corrections are sufficient to reconcile the apparent temperatures deduced using NRS with the accepted properties of Mo, in particular its equation of state.Comment: near-final version, waiting for final consent from an autho