Experimental observation of different-order components of a vibrational wave packet in a bulk dielectric using high-order Raman scattering

We use high-order Raman scattering in a bulk dielectric to characterize coherent dynamics with precision typical for gas phase experiments. The experimental pump-probe approach allows for the simultaneous observation and separation in space and time of the individual contributions of different-order Raman processes to a coherent wave packet without relying on phase-matching conditions and within the same experimental geometry. We propose a novel technique to discriminate between stimulated excitation of vibronic levels in the impulsive and intermediate excitation regimes, futhermore allowing us to distinguish between different pathways contributing to the same fifth-order Raman processes.     

Transport and hydrodynamic calculations of direct photons at FAIR

The microscopic transport model UrQMD and a micro + macro hybrid model are used to calculate direct photon spectra from U+U$\mathrm{U}+\mathrm{U}$-collisions at Elab=35 A GeV$E_{\mathsf{lab}}=35\text{A\hspace{0.17em}GeV}$ as will be measured by the CBM Collaboration at FAIR. In the hybrid model, the intermediate high-density part of the nuclear interaction is described with ideal 3+1$3+1$-dimensional hydrodynamics. Different equations of state of the matter created in the heavy-ion collisions are investigated and the resulting spectra of direct photons are predicted. The emission patterns of direct photons in space and time are discussed.     

A renormalization group analysis of lattice models of two-dimensional membranes

We study lattice models of two-dimensional membranes of interest in statistical physics. The energy functional of a membrane is expressed as a sum of terms proportional to the surface area of the membrane, an extrinsic curvature and an intrinsic curvature quantity, respectively, but we neglect excluded volume effects. We introduce a renormalization transformation for these models which preserves the form of the energy functional, up to nonlocal terms. Our renormalization group construction is used to analyze the phase diagram and the different critical regimes of our models. We find evidence for a crumpling transition, separating a regime where surfaces are crystalline from one where the surfaces collapse to branched polymers, and we find a third genuine random-surface regime.     

B-series analysis of iterated Taylor methods

For stochastic implicit Taylor methods that use an iterative scheme to compute their numerical solution, stochastic B-series and corresponding growth functions are constructed. From these, convergence results based on the order of the underlying Taylor method, the choice of the iteration method, the predictor, and the number of iterations, for Itô and Stratonovich SDEs, and for weak as well as strong convergence are derived. As special case, also the application of Taylor methods to ODEs is considered. The theory is supported by numerical experiments.     

Modeling of coupled deformation-induced twinning and dislocation slip using incremental energy minimization

The complex interplay between dislocations and deformation-induced twinning leads to a relatively poor formability of magnesium at room temperature. For understanding the complicated behavior of this metal, a novel model is presented. It is based on a variational principle. Within this principle based on energy minimization, dislocation slip is modeled by crystal plasticity theory, while the phase decomposition associated with twinning is considered by sequential laminates. The proposed model captures the transformation of the crystal lattice due to twinning in a continuous fashion by simultaneously taking dislocation slip within both, possibly co-existent, phases into account. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)