Few-body correlations in the QCD phase diagram

From the viewpoint of statistical physics, nuclear matter is a strongly correlated many-particle system. Several regimes of the QCD phase diagram should exhibit strong correlations. Here I focus on three- and four-body correlations that might be important in the phase diagram.Comment: 3 pages, 4 figures, contribution to QNP200

Domain-Type-Guided Refinement Selection Based on Sliced Path Prefixes

Abstraction is a successful technique in software verification, and interpolation on infeasible error paths is a successful approach to automatically detect the right level of abstraction in counterexample-guided abstraction refinement. Because the interpolants have a significant influence on the quality of the abstraction, and thus, the effectiveness of the verification, an algorithm for deriving the best possible interpolants is desirable. We present an analysis-independent technique that makes it possible to extract several alternative sequences of interpolants from one given infeasible error path, if there are several reasons for infeasibility in the error path. We take as input the given infeasible error path and apply a slicing technique to obtain a set of error paths that are more abstract than the original error path but still infeasible, each for a different reason. The (more abstract) constraints of the new paths can be passed to a standard interpolation engine, in order to obtain a set of interpolant sequences, one for each new path. The analysis can then choose from this set of interpolant sequences and select the most appropriate, instead of being bound to the single interpolant sequence that the interpolation engine would normally return. For example, we can select based on domain types of variables in the interpolants, prefer to avoid loop counters, or compare with templates for potential loop invariants, and thus control what kind of information occurs in the abstraction of the program. We implemented the new algorithm in the open-source verification framework CPAchecker and show that our proof-technique-independent approach yields a significant improvement of the effectiveness and efficiency of the verification process.Comment: 10 pages, 5 figures, 1 table, 4 algorithm

The alpha-particle in nuclear matter

Among the light nuclear clusters the alpha-particle is by far the strongest bound system and therefore expected to play a significant role in the dynamics of nuclei and the phases of nuclear matter. To systematically study the properties of the alpha-particle we have derived an effective four-body equation of the Alt-Grassberger-Sandhas (AGS) type that includes the dominant medium effects, i.e. self energy corrections and Pauli-blocking in a consistent way. The equation is solved utilizing the energy dependent pole expansion for the sub system amplitudes. We find that the Mott transition of an alpha-particle at rest differs from that expected from perturbation theory and occurs at approximately 1/10 of nuclear matter densities.Comment: 9 pages RevTex file, 1 figure, submitted to Phys. Lett.

Why we need to establish international political psychology

A combination of Psychology with International Relations yields important results and ideas for improving the international world. This chapter proposes to establish International Political Psychology as a discipline with the purpose of harvesting ideas, theories and concepts that derive out of a combination of the above disciplines

Combining k-Induction with Continuously-Refined Invariants

Bounded model checking (BMC) is a well-known and successful technique for finding bugs in software. k-induction is an approach to extend BMC-based approaches from falsification to verification. Automatically generated auxiliary invariants can be used to strengthen the induction hypothesis. We improve this approach and further increase effectiveness and efficiency in the following way: we start with light-weight invariants and refine these invariants continuously during the analysis. We present and evaluate an implementation of our approach in the open-source verification-framework CPAchecker. Our experiments show that combining k-induction with continuously-refined invariants significantly increases effectiveness and efficiency, and outperforms all existing implementations of k-induction-based software verification in terms of successful verification results.Comment: 12 pages, 5 figures, 2 tables, 2 algorithm

Light clusters in nuclear matter of finite temperature

We investigate properties and the distribution of light nuclei (A<4) in symmetric nuclear matter of finite temperature within a microscopic framework. For this purpose we have solved few-body Alt-Grassberger-Sandhas type equations for quasi-nucleons that include self-energy corrections and Pauli blocking in a systematic way. In a statistical model we find a significant influence in the composition of nuclear matter if medium effects are included in the microscopic calculation of nuclei. If multiplicities are frozen out at a certain time (or volume), we expect significant consequences for the formation of light fragments in a heavy ion collision. As a consequence of the systematic inclusion of medium effects the ordering of multiplicities becomes opposite to the law of mass action of ideal components. This is necessary to explain the large abundance of $\alpha$-particles in a heavy ion collision that are otherwise largely suppressed in an ideal equilibrium scenario.Comment: 9 pages, 9 figures, epja-style file

Three- and Four-body correlations in nuclear matter

Few-nucleon correlations in nuclear matter at finite densities and temperatures are explored. Using the Dyson equation approach leads to effective few-body equations that include self energy corrections and Pauli blocking factors in a systematic way. Examples given are the nucleon deuteron in-medium reaction rates, few-body bound states including the \ga-particle, and \ga-particle condensation.Comment: 7 pages, 4 figures, uses Few-Body Systems style file

World polity: anatomy of and arguments for regional and global integration

This article is inspired by taking sort of a medical view on the international political world2. A medical view here means that first we need to understand the anatomy of the organism that we observe, i.e. the world. Secondly, we need to make some diagnoses and prognoses about possible threats to the functioning of this organism as well as how to restore health. In Political Science terms this means identifying threats to security, peace, survival and wellbeing of states, nations, and individuals, as well as the whole, and to identify possible political solutions to these threats. The first part of this article will present the history of global integration and why it is necessary to prevent war and to facilitate peace at the example of Europe. Europe is here regarded a greenhouse for global integration. This part describes the attempts at integration before the major wars in Europe in the last centuries, the reasons for these wars as the failures or lack of integration, and the way it was overcome. The second part of this article will present an ideal type global political anatomy. This will be illustrated with graphics, which are thought to make the global political system better understood by visualising key aspects of it. The third part of this paper will discuss the nature of reality, which is important to understand conflicts in today’s world, as ‘virtual’, material, social and cultural. It will present a challenge to Alexander Wendt’s recent idea of reality as a hologram and discuss how civilizational conflicts, as described by Samuel Huntington, can possibly be resolved by creating a global demos (polity) by establishing a global parliament. As the basis for the latter argument, finally, this paper will present and analyse the results from the survey on global citizenship. Global demos here refer to the idea of a global polity, or identification of the global population with the global, or to say it alternatively: as global citizens. It is argued that, if we would have a global demos, this would facilitate global integration, which is necessary for peace. For example, further global integration towards a world state with a world parliament, is thought to be only possible and sensible if there is a reasonable global demos to build this entity on.For this reason, this article presents results from a survey run at the University of Hull in 2016 intended to measure global citizenship