On the lifetime of the kappa meson

The lifetime of a hypotheticalκ meson with low mass, introduced byGlashow andWeinberg in a model for simultaneous breaking ofSU(3) and chiral symmetry, is calculated. The coupling constant of theκ toKπ is obtained by assuming that the divergence of the strangeness changing vector current is dominated by theκ pole.     

Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity

Electric field-assisted charge carrier photogeneration in a ladder-type methyl-substituted poly(paraphenylene) was investigated by ultrafast absorption spectroscopy at low excitation intensity. The dissociation of excitons into electron-hole pairs occurs from the vibrationally relaxed excited state throughout its lifetime and is caused by the applied electric field, rather than by existence of special "dissociation sites." These findings are of importance for material choice in device applications.     

Editorial

With this volume The European Physical Journal D (EPJ D) continues its tradition of publishing a selection of papers drawn from the bi-annual main conference in the field of cluster physics. The readers should be aware that this is not a conference proceeding in the normal sense of the word, i.e. it is not a collection of all posters and papers presented at this conference. Rather, the guest-editors for this volume of EPJ D have selected only such papers from this conference which comply with the normal high quality standards of a refereed international scientific journal -- in terms of novelty, soundness and scientific quality. The guest-editors have made sure that all papers have been subject to a standard refereeing process which ensures these high standards as expected by the readers of EPJ D. We trust that the specific collection of papers published in this volume will contribute to the future attractiveness of EPJ D especially in the ever growing field of cluster physics.     

Analysis of nonreciprocal light propagation in multimode imaging devices

We investigate a structure consisting of a magneto-optic multimode waveguide and two monomode waveguides serving as in- and outlets. The geometrical dimensions of the multimode waveguide can be adjusted such that the guided modes interfere constructively in forward direction and destructively for backward propagation. In this paper we present concepts for a circulator and two isolators based on multimode imaging.     

Euclidean Steiner trees optimal with respect to swapping 4-point subtrees

The Steiner tree problem in Euclidean space $E^3$ asks for a minimum length network $T$ , called a Euclidean Steiner Minimum Tree (ESMT), spanning a given set of points. This problem is NP-hard and the hardness is inherently due to the number of feasible topologies (underlying graph structure of $T$ ) which increases exponentially as the number of given points increases. Planarity is a very strong condition that gives a big difference between the ESMT problem in the Euclidean plane $E^2$ and in Euclidean $d$ -space $E^d (d\ge 3)$ : the ESMT problem in the plane is practically solvable whereas the ESMT problem in $d$ -space is really intractable. The simplest tree rearrangement technique is to repeatedly replace a subtree spanning four nodes in $T$ with another subtree spanning the same four nodes. This technique is referred to as the Swapping 4-point Topology/ Tree technique in this paper. An indicator (or quasi-indicator) of $T$ plays a similar role in the optimization of the length $L(T)$ of $T$ in the discrete topology space (the underlying graph structure of $T$ ) to the derivative of a differentiable function which indicates a fastest direction of descent. $T$ will be called S4pT-optimal if it is optimal with respect to swapping 4-point subtrees. In this paper we first make a complete analysis of 4-point trees in Euclidean space exploring all possible types of 4-point trees and their properties. We review some known indicators of 4-point ESMTs in $E^2$ , and give some simple geometric proofs of these indicators. Then, we translate these indicators to $E^3$ , producing eight quasi-indicators in $E^3$ using computational experiments, the best quasi-indicator $\rho _\mathrm{osr}$ is sifted with an effectiveness for randomly generated 4-point sets as high as 98.62 %. Finally we show how $\rho _\mathrm{osr}$ is used to find an S4pT-optimal ESMT on 14 probability vectors in $4d$ -space with a detailed example.     

A balanced procedure for the treatment of cluster–ligand interactions on gold phosphine systems in catalysis

Ligand‐protected metal clusters are difficult to describe within density functional theory due to the need to treat the electronic structure of the cluster, possible charge transfer between the ligands and the cluster, and weak ligand–ligand interactions in a balanced manner. We demonstrate the use of an appropriate, stepwise benchmarking process that accounts for the nonadditivity of these different contributions to stability and catalytic activity. We consider both open‐ and closed‐shell clusters, differently charged systems, and ligands of increasing complexity for gold phosphine systems. The use of a dispersion correction to density functional calculations was found to be crucial for both structure optimization and the calculation of binding energies. We find that PBE‐D3 performs well with a variation in energetics of 0.7–10.9 kcal/mol, PBE0‐D3 better with 0.0–3.3 kcal/mol, and B2PLYP‐D3 the best with 0.2–2.4 kcal/mol, when compared to the best available benchmark [CCSD(T) or SCS‐MP2]. Our systematic procedure clarifies that these functionals all give accurate results for certain cases, but for the total performance over a range of interactions, they perform in accordance with Jacob's ladder. © 2014 Wiley Periodicals, Inc.     

Results from a low-energy analysis of the CDMS II germanium data

We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below ～10 GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.