Three dimensional massive scalar field theory and the derivative expansion of the renormalization group

We show that non-perturbative fixed points of the exact renormalization group, their perturbations and corresponding massive field theories can all be determined directly in the continuum -- without using bare actions or any tuning procedure. As an example, we estimate the universal couplings of the non-perturbative three-dimensional one-component massive scalar field theory in the Ising model universality class, by using a derivative expansion (and no other approximation). These are compared to the recent results from other methods. At order derivative-squared approximation, the four-point coupling at zero momentum is better determined by other methods, but factoring this out appropriately, all our other results are in very close agreement with the most powerful of these methods. In addition we provide for the first time, estimates of the n-point couplings at zero momentum, with n=12,14, and the order momentum-squared parts with n=2 ... 10.Comment: 33 pages, 1 eps figure, 7 tables; TeX + harvmac; version to appear in Nucl. Phys.

The Expert Witness in Criminal Cases in France, Germany, and Italy

This paper addresses the impact of social capital on the status attainment process of young people at the start of their careers and examines how social class, gender and ethnicity affect the accumulation of social capital and thereby labour market stratification of young people. A sample of young Swedes graduating from vocational schools and universities between 2005 and 2006, was surveyed via the telephone about their experiences acquiring jobs. Two re­search questions are posed: (i) Which characteristics (class, gender and ethnicity) affect young people's access to more social capital? (ii) How is social capital rewarded in the labour market? The results show that being female, coming from the lower social classes and being a member of a stigmatized immigrant groupare associated with a substantial social capital deficit. When socioeconomic and demographic backgrounds as well as the human capital of respondents are controlled, social capital is positively associated with salary level. The results indicate that social capital is a significant factor in the stratification process of young people

Metaphor and philosophy: an encounter with Derrida

This paper presents a critical analysis of the central argument of Derrida's paper 'White Mythology'. The crucial claims are that the concept of metaphor presupposes philosophy, that philosophy presupposes the concept of metaphor, and that philosophy cannot accommodate the concept of metaphor. I offer support for the first two claims, explaining the general kind of view of philosophy and of metaphor which they require, but I argue that even if we grant the first two claims, the concept of metaphor only presents a difficulty for a particular conception of philosophy, rather that philosophy as such

Large N and the renormalization group

In the large N limit, we show that the Local Potential Approximation to the flow equation for the Legendre effective action, is in effect no longer an approximation, but exact - in a sense, and under conditions, that we determine precisely. We explain why the same is not true for the Polchinski or Wilson flow equations and, by deriving an exact relation between the Polchinski and Legendre effective potentials (that holds for all N), we find the correct large N limit of these flow equations. We also show that all forms (and all parts) of the renormalization group are exactly soluble in the large N limit, choosing as an example, D dimensional O(N) invariant N-component scalar field theory.Comment: 13 pages, uses harvmac; Added: one page with further clarification of the main results, discussion of earlier work, and new references. To be published in Phys. Lett.

On the Fixed-Point Structure of Scalar Fields

In a recent Letter (K.Halpern and K.Huang, Phys. Rev. Lett. 74 (1995) 3526), certain properties of the Local Potential Approximation (LPA) to the Wilson renormalization group were uncovered, which led the authors to conclude that $D>2$ dimensional scalar field theories endowed with {\sl non-polynomial} interactions allow for a continuum of renormalization group fixed points, and that around the Gaussian fixed point, asymptotically free interactions exist. If true, this could herald very important new physics, particularly for the Higgs sector of the Standard Model. Continuing work in support of these ideas, has motivated us to point out that we previously studied the same properties and showed that they lead to very different conclusions. Indeed, in as much as the statements in hep-th/9406199 are correct, they point to some deep and beautiful facts about the LPA and its generalisations, but however no new physics.Comment: Typos corrected. A Comment - to be published in Phys. Rev. Lett. 1 page, 1 eps figure, uses LaTeX, RevTex and eps