Diffractive dissociation into KsK±π∓π−K_sK^{\pm}\pi^{\mp}\pi^{-} final states

The COMPASS fixed-target experiment at CERN/SPS is dedicated to the study of hadron structure and spectroscopy, especially the search for spin-exotic states. After having started to study the existence of the spin-exotic $\pi_1(1600)$ resonance in the 2004 pilot-run data, the new 2008/09 data will enable us to further clarify the situation. Apart from the $\pi_1(1600)$ resonance, also a spin-exotic $\pi_1(2000)$ was reported in the past in the $f_1(1285)\pi$ decay channel by the E852/BNL experiment, however, this state still lacks confirmation. We present a first event selection of the diffractively produced $(K\bar{K}\pi\pi)^{-}$ system showing clean $f_1(1285)$ and $f_1(1420)$ resonances at competing statistics. A partial-wave analysis started on $f_1(1285)\pi$ and $f_1(1420)\pi$ decay channels will further complete the search for spin-exotics in the 2008/09 COMPASS data.Comment: 4 pages, 6 figures, Hadron2011 Conference Proceedings, to appear in the proceedings of the XIV International Conference on Hadron Spectroscopy: Hadron 2011, Munich, Germany, 13-17 June 201

Four-gluon scattering at three loops, infrared structure and Regge limit

We compute the three-loop four-gluon scattering amplitude in maximally supersymmetric Yang-Mills theory, including its full color dependence. Our result is the first complete computation of a non-planar four-particle scattering amplitude to three loops in four-dimensional gauge theory and consequently provides highly non-trivial data for the study of non-planar scattering amplitudes. We present the amplitude as a Laurent expansion in the dimensional regulator to finite order, with coefficients composed of harmonic poly-logarithms of uniform transcendental weight, and simple rational prefactors. Our computation provides an independent check of a recent result for three-loop corrections to the soft anomalous dimension matrix that predicts the general infrared singularity structure of massless gauge theory scattering amplitudes. Taking the Regge limit of our result, we determine the three-loop gluon Regge trajectory. We also find agreement with very recent predictions for sub-leading logarithms

Higher-Order Process Modeling: Product-Lining, Variability Modeling and Beyond

We present a graphical and dynamic framework for binding and execution of business) process models. It is tailored to integrate 1) ad hoc processes modeled graphically, 2) third party services discovered in the (Inter)net, and 3) (dynamically) synthesized process chains that solve situation-specific tasks, with the synthesis taking place not only at design time, but also at runtime. Key to our approach is the introduction of type-safe stacked second-order execution contexts that allow for higher-order process modeling. Tamed by our underlying strict service-oriented notion of abstraction, this approach is tailored also to be used by application experts with little technical knowledge: users can select, modify, construct and then pass (component) processes during process execution as if they were data. We illustrate the impact and essence of our framework along a concrete, realistic (business) process modeling scenario: the development of Springer's browser-based Online Conference Service (OCS). The most advanced feature of our new framework allows one to combine online synthesis with the integration of the synthesized process into the running application. This ability leads to a particularly flexible way of implementing self-adaption, and to a particularly concise and powerful way of achieving variability not only at design time, but also at runtime.Comment: In Proceedings Festschrift for Dave Schmidt, arXiv:1309.455

Concurrence of dynamical phase transitions at finite temperature in the fully connected transverse-field Ising model

We construct the finite-temperature dynamical phase diagram of the fully connected transverse-field Ising model from the vantage point of two disparate concepts of dynamical criticality. An analytical derivation of the classical dynamics and exact diagonalization simulations are used to study the dynamics after a quantum quench in the system prepared in a thermal equilibrium state. The different dynamical phases characterized by the type of non-analyticities that emerge in an appropriately defined Loschmidt-echo return rate directly correspond to the dynamical phases determined by the spontaneous breaking of $\mathbb{Z}_2$ symmetry in the long-time steady state. The dynamical phase diagram is qualitatively different depending on whether the initial thermal state is ferromagnetic or paramagnetic. Whereas the former leads to a dynamical phase diagram that can be directly related to its equilibrium counterpart, the latter gives rise to a divergent dynamical critical temperature at vanishing final transverse-field strength.Comment: journal article, 15 pages, 12 figures. Final versio

Decision Rules, Transparency and Central Banks

The trade-off between price stability and output stabilization is in the centre of monetary policy-making. This trade-off enters many macroeconomic models as the central bank is assumed to minimize some loss function consisting of inflation deviations and output deviations from some specific targets. The policy instrument to control these variables is the short-term interest rate. Monetary policy-making is usually conducted in committees, whose members may have conflicting interests. This is evident for the Governing Council of the European Central Bank or the Board of Governors of the Federal Reserve System in the United States. In this thesis we take a closer look at monetary policy committees. In particular, we address how decision rules and transparency requirements concerning such rules in monetary policy committees should be designed. In particular we concern ourself with the following two issues: 1. Which type of majority rule should be applied in the monetary policy committee? 2. Should the public know which decision rule the monetary policy committee applies and should the central bankers release their information about economic shocks? To address these questions, standard monetary models with aggregate demand and supply shocks are introduced and we assume that a committee decides about the interestrate change according to some voting rule. We develop a flexible majority rule, where the majority for interest-rate changes depends itself on the size of the interest-rate change. Our main findings are: First, a well-designed flexible majority rule can improve welfare compared to a fixed majority rule in a simple shock structure. This insight is robust, if we apply more complex shock structures or if we introduce a simple dynamic setup. Second, transparency regarding the rule has ambiguous effects on welfare and it may not be necessary to publish the decision rule, but within our framework, we can provide a best combination of a decision rule and an information setup

construct dikes or erect windmills? A synthesis of cultural theory and new institutional economics perspectives

Climate change affects the entire globe. However, its effects are influenced by differing geographic expositions and unevenly spread social adaptation capacities. Empirically, different levels of social vulnerability can be observed which are explained by distinct levels of wealth – so the general explanation goes. Such correlations cannot be neglected and are quite trivial: assuming similar expositions, The Netherlands are better prepared to construct dikes against flooding than Bangladesh. But what is about different vulnerabilities occurring despite of comparable levels of wealth? Why is it that the Mississippi delta was devastated by hurricane Katrina whereas the Rhine-Meuse delta remained almost unaffected up to now? What accounts for the fact that Texas, not really know for caring much for environmental niceties, has set up more windmills than California and is close to outpace Denmark and Germany with respect to the production of wind power? How can it be that Texas nevertheless rejects any environmental political guidelines from Washington? These questions are discussed by amalgamating the Cultural Theory (Douglas/Wildavsky 1982, Schwarz/Thompson 1990) and the Varieties of Capitalism approach (Hall/Soskice 2001). The rationality behind this idea is that societies which are rather coined by collective and egalitarian principles are better prepared to cope with cooperative tasks like building dikes whereas individualistic institutions and convictions result in a situation in which the rich seek shelter whereas the poor are left alone. Contrary, it is easier to realize (environmental-)innovations like windmills within a liberal context. That is because it is easier to raise venture capital and to overcome opposition within the neighbourhood (among other things). Our theoretical argument picks up the vaguely claimed correlation of cultural frames of interpretation and socio-economic institutions (Dryzek 2008, Mamadouh 1999) and explores it in greater depth

Fast logarithmic Fourier-Laplace transform of nonintegrable functions

We present an efficient and very flexible numerical fast Fourier-Laplace transform, that extends the logarithmic Fourier transform (LFT) introduced by Haines and Jones [Geophys. J. Int. 92(1):171 (1988)] for functions varying over many scales to nonintegrable functions. In particular, these include cases of the asymptotic form $f(\nu\to0)\sim\nu^a$ and $f(|\nu|\to\infty)\sim\nu^b$ with arbitrary real $a>b$. Furthermore, we prove that the numerical transform converges exponentially fast in the number of data points, provided that the function is analytic in a cone $|\Im{\nu}|<\theta|\Re{\nu}|$ with a finite opening angle $\theta$ around the real axis and satisfies $|f(\nu)f(1/\nu)|<\nu^c$ as $\nu\to 0$ with a positive constant $c$, which is the case for the class of functions with power-law tails. Based on these properties we derive ideal transformation parameters and discuss how the logarithmic Fourier transform can be applied to convolutions. The ability of the logarithmic Fourier transform to perform these operations on multiscale (non-integrable) functions with power-law tails with exponentially small errors makes it the method of choice for many physical applications, which we demonstrate on typical examples. These include benchmarks against known analytical results inaccessible to other numerical methods, as well as physical models near criticality.Comment: 14 pages, 8 figure

Searching for patterns in political event sequences: Experiments with the KEDs database

This paper presents an empirical study on the possibility of discovering interesting event sequences and sequential rules in a large database of international political events. A data mining algorithm first presented by Mannila and Toivonen (1996), has been implemented and extended, which is able to search for generalized episodes in such event databases. Experiments conducted with this algorithm on the Kansas Event Data System (KEDS) database, an event data set covering interactions between countries in the Persian Gulf region, are described. Some qualitative and quantitative results are reported, and experiences with strategies for reducing the problem complexity and focusing on the search on interesting subsets of events are described