Chiral symmetry breaking in the Wegner-Houghton approach

The Wegner-Houghton formulation of the exact renormalization group evolution equation is used in order to study the chiral symmetry breaking of the linear sigma model coupled to an isospin doublet of quarks. A numerical investigation for a particular truncation of the equation which includes the scalar field renormalization function is presented.Comment: 4 pages,4 eps figures. Contribution to CRIS2000, Catania, May 200

Hybrid star structure with the Field Correlator Method

We explore the relevance of the color-flavor locking phase in the equation of state (EoS) built with the Field Correlator Method (FCM) for the description of the quark matter core of hybrid stars. For the hadronic phase, we use the microscopic Brueckner-Hartree-Fock (BHF) many-body theory, and its relativistic counterpart, i.e. the Dirac-Brueckner (DBHF). We find that the main features of the phase transition are directly related to the values of the quark-antiquark potential $V_1$, the gluon condensate $G_2$ and the color-flavor superconducting gap $\Delta$. We confirm that the mapping between the FCM and the CSS (constant speed of sound) parameterization holds true even in the case of paired quark matter. The inclusion of hyperons in the hadronic phase and its effect on the mass-radius relation of hybrid stars is also investigated.Comment: 15 pages, 8 figures ; revised version to be published in the EPJA Topical Issue on "Exotic Matter in Neutron Stars

Renormalization group analysis of the three-dimensional Gross-Neveu model at finite temperature and density

The Renormalization Group flow equations obtained by means of a proper time regulator are used to analyze the restoration of the discrete chiral symmetry at non-zero density and temperature in the Gross-Neveu model in d=2+1 dimensions. The effects of the wave function renormalization of the auxiliary scalar field on the transition have been studied. The analysis is performed for a number of fermion flavors N_f=12 and the limit of large N_f is also considered. The results are compared with those coming from lattice simulations.Comment: Latex file, 12 pages, 2 eps figures, minor changes, added references, published versio

Proper time regulator and Renormalization Group flow

We consider some applications of the Renormalization Group flow equations obtained by resorting to a specific class of proper time regulators. Within this class a particular limit that corresponds to a sharpening of the effective width of the regulator is investigated and a procedure to analytically implement this limit on the flow equations is shown. We focus on the critical exponents determination for the O(N) symmetric scalar theory in three dimensions. The large N limit and some perturbative features in four dimensions are also analysed. In all problems examined the results are optimized when the mentioned limit of the proper time regulator is taken.Comment: 22 pages, 4 eps figure

The Emergence of the ‘Social Economy’: the Australian not-for-profit sector in transition

The Not-for-Profit (NFP) sector in Australia is currently in transition. There is a growing recognition, in Australia and worldwide, that government and philanthropic funds are insufficient to address the problems facing society; as well as demands for increased accountability and demonstration of improved outcomes from traditional funding to the non-profit sector. There is also a growing global interest in social enterprises, socially responsible investment, and, in particular, impact investing – where investors aim to achieve a blend between commercial value and social impact. These trends are contributing to the emergence of new organizational forms, partnerships and financial products, and as a consequence, NFP organizations are becoming just one form of organization within the broader spectrum of organizations and activity described as the ‘social economy’. This research project begins to explore this transition by analysing a sample of organizations in Australia that while having formal non-profit structures, identified themselves as social enterprises in a bid for funding from one of Australia’s leading corporate foundations, the Westpac Foundation. The research builds on previous studies, yet also enables more detailed data on the leadership, governance, human resources, financial challenges, and focus of activities of social enterprises and raises questions about the future of the sector and the social economy