Shear Viscosities from Kubo Formalism in a large-NcN_{\rm c} Nambu--Jona-Lasinio Model

In this work the shear viscosity of strongly interacting matter is calculated within a two-flavor Nambu--Jona-Lasinio model as a function of temperature and chemical potential. The general Kubo formula is applied, incorporating the full Dirac structure of the thermal quark spectral function and avoiding commonly used on-shell approximations. Mesonic fluctuations contributing via Fock diagrams provide the dominant dissipative processes. The resulting ratio $\eta/s$ (shear viscosity over entropy density) decreases with temperature and chemical potential. Interpolating between our NJL results at low temperatures and hard-thermal-loop results at high temperatures a minimum slightly above the AdS/CFT benchmark $\eta/s=1/4\pi$ is obtained.Comment: 15 pages, 11 figures. Revision with minor corrections matches published versio

Musealizing the European Union and Its History: Institutions, Actors and Networks

The two chapters employ the concepts of MLG and networks to capture the character of the politics and policy-making of cultural policy in the EU with a particular focus on more recent attempts at the Europeanisation of (history) museums through (inter alia) changing their content and narratives. The concepts are, however, employed as heuristic tools only in these draft chapters for a book written for a cross-disciplinary audience and a larger market including museum practitioners. The research is based on wide-ranging document analysis, visits to and the analysis of some 90 museums and temporary exhibitions across Europe and some 60 interviews with politicians and officials involved in cultural policy making in state institutions at European and national levels as as well as societal actors including NGOs, historians and museum directors and curators. The core arguments in these two draft chapters and this part of the forthcoming book are as follows: 1. Due to the EU‟s still very limited formal competences in cultural policy and the crucial importance of this policy field for national and regional polities and identities, politics and policy-making in the field of culture is very highly fragmented. As a result, the limited existing works by sociologists like Chris Shore and political scientists like Tobais Theiler and Annabelle Littoz-Monnet (for references see the bibliography at the end of the draft chapters), which focus exclusively on “Brussels”, fail to capture the complexity of this field. 2. My draft chapters and our book aim to overcome these limits with a two-fold strategy: first, I broaden the perspective to discuss a multitude of state actors in the specific field of musealization of the European Union and European integration to include national and especially regional actors. The research shows that regional actors in cultural fragmented and constitutionally decentralized or federal member-states buy 2 into the Europeanization agenda because it strengthens regional narratives and identities. Even in member-states like France with constitutionally comparatively weak regions, but quite strong regional identities in some parts, some regions strongly support the European embedding of their museal representation strategies to enhance the legitimacy of their powers and to strengthen regional identity. 3. Secondly, I argue that it is crucially necessary to go beyond the study of state actors in the museum field (and cultural heritage more generally). In the second chapter I discuss the role of professional groups (esp. historians and museum practitioners) in the Europeanization processes we observe, their partly formalized but largely informal networking activities and the particular role of individual cultural entrepreneurs. This broadly transnational sociological perspective demonstrates that attempts to transnationalize and Europeanize museal narratives are to a large degree driven from below and not entirely dependent on EU initiative or funding, although they draw upon it wherever possible. 4. This research challenges in particular the strongly normative idea in Shore (2000) and similar works that the EU approach to cultural policy is hierarchical and instrumental and that this is outdated and bad. Instead, cultural politics and policy-making is best understood as a highly disorganized and chaotic field with multiple state and non-state actors with very different motivations and objectives. Even at EU level, the politics and policy-making of cultural integration is less geared towards policy-making than what might be called project-making, i.e. inserting particular agendas and ideas into funding priorities and funding streams and obtaining such funding. 5. Moreover, the research also demonstrates that rational choice explanations are of limited value for assessing the motivations of the multiple actors in this field, and in the particular area of Europeanization of museums and historical narratives. It becomes clear that many societal actors in particular are not just driven by gaining access to funding. In fact, such funding is often insignificant, esp. in the Culture 2007- 13 programme as opposed to Interreg funding, for example, its administration is excessively bureaucratic and its function is at best that of providing seed funding to facilitate the establishment of more long-term cross-national forms of cooperation among relevant actors like museums. Rather, many of the non-state actors are mainly driven by their ideational beliefs. They include (inter alia) a strong belief that national narratives, which have derived from nineteenth-century nationalism, are outmoded; that museums have to transnationalize their working methods and content; that this often means Europeanizing their content and narratives in the first instance, esp. in member-states without a colonial tradition or non-European inward-migration; that in representations of contemporary history this might mean strengthening references to the EU, but less as an institutional space of politics and policy-making and more as a economic and social space of ever closer communication and interaction; and that such a transformation of museums and their content and narratives can also act as a barrier against nationalist populist movements and political parties which have recently had electoral success in member-states like Sweden, Denmark and the Netherlands. 6. At the most general level, the draft chapters and the book as a whole argue strongly for a perspective on culture and “Europe”, the EU and European integration which is much less Brussels-centred and much less state-centric in its treatment of “Brussels”. At the most general level, the chapters and the book also advocate a strongly transdisciplinary cooperation across the social sciences and humanities which helps to overcome the excessive focus of the limited political science research in this field on state institutions and policy-making and of sociological research on “Brussels” and EU-level elites neglecting the transnational and transnational elites

Nuclear density functional constrained by low-energy QCD

We have developed a relativistic point-coupling model of nuclear many-body dynamics constrained by the low-energy sector of QCD. The effective Lagrangian is characterized by density-dependent coupling strengths determined by chiral one- and two-pion exchange (with single and double delta isobar excitations) and by large isoscalar background fields that arise through changes of the quark condensate and the quark density at finite baryon density. The model has been tested in the analysis of nuclear ground-state properties along different isotope chains of medium and heavy nuclei. The agreement with experimental data is comparable with purely phenomenological predictions. The built-in QCD constraints and the explicit treatment of pion exchange restrict the freedom in adjusting parameters and functional forms of density-dependent couplings. It is shown that chiral pionic fluctuations play an important role for nuclear binding and saturation mechanism, whereas background fields of about equal magnitude and opposite sign generate the effective spin-orbit potential in nuclei.Comment: ws-procs9x6.cls, 8 pgs, Talk presented at "X Convegno su Problemi di Fisica Nucleare Teorica", Cortona (AR), 6-9 october 200

Alpha-clustered hypernuclei and chiral SU(3) dynamics

Light hypernuclei with an $\alpha$ cluster substructure of the core nucleus are studied using an accurate cluster approach (the Hyper-THSR wave function) in combination with a density-dependent $\Lambda$ hyperon-nuclear interaction derived from chiral SU(3) effective field theory. This interaction includes important two-pion exchange processes involving $\Sigma N$ intermediate states and associated three-body mechanisms as well as effective mass and surface terms arising in a derivative expansion of the in-medium $\Lambda$ self-energy. Applications and calculated results are presented and discussed for $_\Lambda^9$Be and $^{13}_\Lambda$C. Furthermore, the result of the lightest $\alpha$ clustered hypernucleus, $^5_{\Lambda}$He using realistic $ab initio$ four nucleon density is shown.Comment: To be submitted in PTE

Nuclear thermodynamics from chiral low-momentum interactions

We investigate the thermodynamic equation of state of isospin-symmetric nuclear matter with microscopic nuclear forces derived within the framework of chiral effective field theory. Two- and three-body nuclear interactions constructed at low resolution scales form the basis for a perturbative calculation of the finite-temperature equation of state. The nuclear force models and many-body methods are benchmarked against bulk properties of isospin-symmetric nuclear matter at zero temperature, which are found to be well reproduced when chiral nuclear interactions constructed at the lowest resolution scales are employed. The calculations are then extended to finite temperatures, where we focus on the liquid-gas phase transition and the associated critical point. The Maxwell construction is applied to construct the physical equation of state, and the value of the critical temperature is determined to be T_c =17.2-19.1 MeV, in good agreement with the value extracted from multifragmentation reactions of heavy ions.Comment: 22 pages, 12 figures, 2 tables. v3 matches published versio