QQˉQ\bar Q potential from AdS-CFT relation at T≥0T\geq 0: Dependence on orientation in internal space and higher curvature corrections

Within the classical approximation we calculate the static $Q\bar Q$ potential via the AdS/CFT relation for nonzero temperature and arbitrary internal orientation of the quarks. We use a higher order curvature corrected target space background. For timelike Wilson loops there arises a critical line in the orientation-distance plane which is shifted to larger distances relative to the calculation with uncorrected background. Beyond that line there is no $Q\bar Q$-force. The overall vanishing of the force for antipodal orientation known from zero tempera ture remains valid. The spacelike Wilson loops yield a string tension for a (2+1)-dimensional gauge theory, independent of the relative internal orientation, but sensitive to the background correction.Comment: Used background has been adapted to hep-th/9808126 and revised version of hep-th/9805156, slightly changed comment on 1/L ter

Operator product expansion of the energy momentum tensor in 2D conformal field theories on manifolds with boundary

Starting from the well-known expression for the trace anomaly we derive the $T\cdot T$ operator product expansion of the energy-momentum tensor in 2D conformal theories defined in the upper halfplane $without$ making use of the additional condition of no energy-momentum flux across the boundary. The OPE turns out to be the same as in the absence of the boundary. For this result it is crucial that the trace anomaly is proportional to the Gau\ss-Bonnet density. Some relations to the $\sigma$ - model approach for open strings are discussed.Comment: 8 pages, Latex, HU Berlin-IEP-93/

Two and three-point functions in Liouville theory

Based on our generalization of the Goulian-Li continuation in the power of the 2D cosmological term we construct the two and three-point correlation functions for Liouville exponentials with generic real coefficients. As a strong argument in favour of the procedure we prove the Liouville equation of motion on the level of three-point functions. The analytical structure of the correlation functions as well as some of its consequences for string theory are discussed. This includes a conjecture on the mass shell condition for excitations of noncritical strings. We also make a comment concerning the correlation functions of the Liouville field itself.Comment: 15 pages, Latex, Revised version: A sign error in formula (50) is correcte

On gravitational dressing of renormalization group beta-functions beyond lowest order of perturbation theory

Based on considerations in conformal gauge I derive up to nextleading order a relation between the coefficients of beta-functions in 2D renormalizable field theories before and after coupling to gravity. The result implies a coupling constant dependence of the ratio of both beta-functions beyond leading order.Comment: DESY 94-?, HU Berlin-IEP-94/21, 9 pages, Late

Comments on the scalar propagator in AdS x S and the BMN plane wave

We discuss the scalar propagator on generic AdS_{d+1} x S^{d'+1} backgrounds. For the conformally flat situations and masses corresponding to Weyl invariant actions the propagator is powerlike in the sum of the chordal distances with respect to AdS_{d+1} and S^{d'+1}. In all other cases the propagator depends on both chordal distances separately. We discuss the KK mode summation to construct the propagator in brief. For AdS_5 x S^5 we relate our propagator to the expression in the BMN plane wave limit and find a geometric interpretation of the variables occurring in the known explicit construction on the plane wave.Comment: 7 pages, Fortsch.Phys. style, Talk given at 36th International Symposium Ahrenshoop on the Theory of Elementary Particles: Recent Developments in String/M- Theory and Field Theory, Wernsdorf, Germany, 26-30 Aug 200

The Growth of Low Skill Service Jobs and the Polarization of the U.S. Labor Market

We offer an integrated explanation and empirical analysis of the polarization of U.S. employment and wages between 1980 and 2005, and the concurrent growth of low skill service occupations. We attribute polarization to the interaction between consumer preferences, which favor variety over specialization, and the falling cost of automating routine, codifiable job tasks. Applying a spatial equilibrium model, we derive, test, and confirm four implications of this hypothesis. Local labor markets that were specialized in routine activities differentially adopted information technology, reallocated low skill labor into service occupations (employment polarization), experienced earnings growth at the tails of the distribution (wage polarization), and received inflows of skilled labor.