Planar radiation zeros in five-parton QCD amplitudes

We demonstrate the existence of `planar', or `type-II', radiation zeros in 5-parton QCD scattering processes. That is, the Born amplitudes are shown to completely vanish for particular kinematic configurations, when all the particle 3-momenta lie in a plane. This result is shown to follow particularly simply from the known BCJ relations between the colour-ordered tree amplitudes, and the MHV formalism is used to express the additional kinematic constraint as a relatively simple expression in terms of only rapidity differences between the final-state partons. In addition, we find that zeros exist for non-planar configurations of the final-state partons, but for which the normal `type-I' conditions on the particle four-momenta do not generally apply. We present numerical results and comment on the possibility of observing planar radiation zeros in hadronic collisions, via central exclusive three-jet production.Comment: 22 pages, 5 figures. Version accepted for publication in JHE

Lateral coupled cavity semiconductor laser

We report the fabrication and operation of a lateral coupled cavity semiconductor laser that consists of two phase-locked parallel lasers of different lengths and with separate electrical contacts. Mode selectivity that results from the interaction between the two supermodes is investigated experimentally. Frequency selectivity and tunability are obtained by controlling the current to each laser separately. Highly stable single mode operation is also demonstrated

Frequency selectivity in laterally coupled semiconductor laser arrays

A longitudinal-mode analysis of a system of laterally coupled waveguided resonators is presented in the coupled-mode approximation. It is shown that variations in the mirror reflectivity of the individual channels result in coupling between the supermodes of the structure. This may lead to mode suppression by modulation of the threshold gain of different Fabry-Perot modes

Women, Work, and Motherhood: Changing Employment Penalties for Motherhood in West Germany after 1945 -- A Comparative Analysis of Cohorts Born in 1934-1971

This paper deals with the effects of entry into motherhood on women's employment dynamics. Our analysis is based on the complete lifetime working- and income histories of a 1% sample of all persons born between 1934 and 1971 and employed in West Germany sometime between 1975 and 1995. We use the records of women who were employed before the birth of their first child. We apply a semi-parametric hierarchical Bayesian modeling approach simultaneously including several time scales and further covariates whose effects we estimate by MCMC techniques. We investigate short-term consequences of entry into motherhood and their changes over different birth cohorts and thereby take into account the employment histories before the birth of the first child. We conduct two models differentiating between the simple return to the labor market and the return for at least a certain period in order to measure subsequent employment stability. Our results indicate that a higher extent of employment experience, a stronger attachment to the labor market and an employment in white collar jobs reduces the employment penalty for mothers after the birth of their first child

A system identification based approach for pulsed eddy current non-destructive evaluation

This paper is concerned with the development of a new system identification based approach for pulsed eddy current non-destructive evaluation and the use of the new approach in experimental studies to verify its effectiveness and demonstrate its potential in engineering applications

Quantum phase transition in the Dicke model with critical and non-critical entanglement

We study the quantum phase transition of the Dicke model in the classical oscillator limit, where it occurs already for finite spin length. In contrast to the classical spin limit, for which spin-oscillator entanglement diverges at the transition, entanglement in the classical oscillator limit remains small. We derive the quantum phase transition with identical critical behavior in the two classical limits and explain the differences with respect to quantum fluctuations around the mean-field ground state through an effective model for the oscillator degrees of freedom. With numerical data for the full quantum model we study convergence to the classical limits. We contrast the classical oscillator limit with the dual limit of a high frequency oscillator, where the spin degrees of freedom are described by the Lipkin-Meshkov-Glick model. An alternative limit can be defined for the Rabi case of spin length one-half, in which spin frequency renormalization replaces the quantum phase transition.Comment: 1o pages, 10 figures, published versio

Photon-Photon Collisions with SuperChic

The SuperChic Monte Carlo generator provides a common platform for QCD-mediated, photoproduction and photon-induced Central Exclusive Production (CEP), with a fully differential treatment of soft survival effects. In these proceedings we summarise the processes generated, before discussing in more detail those due to photon-photon collisions, paying special attention to the correct treatment of the survival factor. We briefly consider the light-by-light scattering process as an example, before discussing planned extensions and refinements for the generator.Comment: 6 pages, 2 figures. Submitted to proceedings of the PHOTON 2017 conferenc

Quantum critical behaviour of the plateau-insulator transition in the quantum Hall regime

High-field magnetotransport experiments provide an excellent tool to investigate the plateau-insulator phase transition in the integral quantum Hall effect. Here we review recent low-temperature high-field magnetotransport studies carried out on several InGaAs/InP heterostructures and an InGaAs/GaAs quantum well. We find that the longitudinal resistivity $\rho_{xx}$ near the critical filling factor $\nu_{c}$ ~ 0.5 follows the universal scaling law $\rho_{xx}(\nu, T) \propto exp[-\Delta \nu/(T/T_{0})^{\kappa}]$, where $\Delta \nu =\nu -\nu_{c}$. The critical exponent $\kappa$ equals $0.56 \pm 0.02$, which indicates that the plateau-insulator transition falls in a non-Fermi liquid universality class.Comment: 8 pages, accepted for publication in Proceedings of the Yamada Conference LX on Research in High Magnetic Fields (August 16-19, 2006, Sendai