Fragmentation in the Governance of EU External Relations: Legal Institutional Dilemmas and the New Constitution for Europe

The European Union, an Ongoing Process of Integration contains 27 original contributions authored by prominent EU lawyers from academia and practice and concentrates on the three main areas of European integration that mark the career path of Alfred E. Kellermann: institutional and constitutional aspects (part I), general principles and substantive aspects (part II), and new Member States and Eastern Europe (part III). The contributions included in this Liber Amicorum vary from thematic in-depth studies to studies of a comparative nature. Their themes cover, inter alia, the structure of the Union according to the Constitution for Europe, the changes and challenges with which the Union¿s institutions are faced, including the creation of the positions of the President of the European Council and the Union Minister for Foreign Affairs, the future paths of flexibility (enhanced cooperation, partial agreements and pioneer groups), the role of national competition authorities and national courts under Regulation 1/2003, the constitutional preparation for EU accession in the new Member States, and the influence of European integration on the development of law in Russia. All contributions have been written in honour of Alfred E. Kellermann. Born in The Hague, raised in Switzerland during the Second World War and having studied and trained at Leiden University and at the European Commission¿s Legal Service in Brussels in the founding years of the European integration process, Doctor Honoris Causa Alfred E. Kellermann is a European by nature and vocation. For almost forty years, Alfred E. Kellermann has worked for the T.M.C. Asser Institute in The Hague. For many, he has become the face of the Institute in the Netherlands and abroad. This is the result of his work as a lecturer and consultant in EU law in countless short and long-term projects all over Europe, including Russia. Perhaps his finest accomplishment in raising awareness and expertise in the law of the European Union concerns the organisation of the famous `Asser Colloquia¿ on EU law and the publication of their proceedings

Critical Entropy of Quantum Heisenberg Magnets on Simple-Cubic Lattices

We analyze the temperature dependence of the entropy of the spin-1/2 Heisenberg model on the three-dimensional simple-cubic lattice, for both the case of antiferromagnetic and ferromagnetic nearest neighbor exchange interactions. Using optimized extended ensemble quantum Monte Carlo simulations, we extract the entropy at the critical temperature for magnetic order from a finite-size scaling analysis. For the antiferromagnetic case, the critical entropy density equals 0.341(5)$k_B$, whereas for the ferromagnet, a larger value of 0.401(5) $k_B$ is obtained. We compare our simulation results to estimates put forward recently in studies assessing means of realizing the antiferromagnetic N\'eel state in ultra-cold fermion gases in optical lattices.Comment: 3 pages, 2 figures; published versio

Magnetocaloric effect in quantum spin-s chains

We compute the entropy of antiferromagnetic quantum spin-s chains in an external magnetic field using exact diagonalization and Quantum Monte Carlo simulations. The magnetocaloric effect, i.e., temperature variations during adiabatic field changes, can be derived from the isentropes. First, we focus on the example of the spin-s=1 chain and show that one can cool by closing the Haldane gap with a magnetic field. We then move to quantum spin-s chains and demonstrate linear scaling with $s$ close to the saturation field. In passing, we propose a new method to compute many low-lying excited states using the Lanczos recursion.Comment: 11 pages including 6 figures, to appear in Condensed Matter Physics (Lviv

What do WMAP and SDSS really tell about inflation?

We derive new constraints on the Hubble function H(phi) and subsequently on the inflationary potential V(phi) from WMAP 3-year data combined with the Sloan Luminous Red Galaxy survey (SDSS-LRG), using a new methodology which appears to be more generic, conservative and model-independent than in most of the recent literature, since it depends neither on the slow-roll approximation, nor on any extrapolation scheme for the potential beyond the observable e-fold range, nor on additional assumptions about initial conditions for the inflaton velocity. This last feature represents the main improvement of this work, and is made possible by the reconstruction of H(phi) prior to V(phi). Our results only rely on the assumption that within the observable range, corresponding to ~ 10 e-folds, inflation is not interrupted and the function H(phi) is smooth enough for being Taylor-expanded at order one, two or three. We conclude that the variety of potentials allowed by the data is still large. However, it is clear that the first two slow-roll parameters are really small while the validity of the slow-roll expansion beyond them is not established.Comment: 5 pages, 3 figures. Numerical module available at http://wwwlapp.in2p3.fr/~valkenbu/inflationH/ . References added, discussion expande

The European Court of Justice blocks the EU's accession to the ECHR

The European Court of Justice delivered a long-awaited opinion on the accession of the European Union to the European Convention of Human Rights (Opinion 2/13) on 18 December 2014. To the surprise of many, the judges in Luxembourg held that the draft Accession Agreement is not compatible with the EU treaties because it undermines the autonomy of EU law. As a consequence, the negotiators will be called back to the drawing board to take the Court’s conclusions into account, or to come up with other solutions. The Accession Agreement would require a major revision, not just cosmetic changes. Moreover, any deal would require the consent of all ECHR contracting parties, including Turkey and Russia. With this opinion, the Court of Justice went against the will of the member states and has thus put itself on a collision course with them

Supersolids in confined fermions on one-dimensional optical lattices

Using quantum Monte Carlo simulations, we show that density-density and pairing correlation functions of the one-dimensional attractive fermionic Hubbard model in a harmonic confinement potential are characterized by the anomalous dimension $K_\rho$ of a corresponding periodic system, and hence display quantum critical behavior. The corresponding fluctuations render the SU(2) symmetry breaking by the confining potential irrelevant, leading to structure form factors for both correlation functions that scale with the same exponent upon increasing the system size, thus giving rise to a (quasi)supersolid.Comment: 4 pages, 5 figures, published versio