R-parity from the heterotic string

In T-duality invariant effective supergravity with gaugino condensation as the mechanism for supersymmetry breaking, there is a residual discrete symmetry that could play the role of R-parity in supersymmetric extensions of the Standard Model.Comment: 9 page

Phenomenology and cosmology of weakly coupled string theory

The weakly coupled vacuum of $E_8\otimes E_8$ heterotic string theory remains an attractive scenario for phenomenolgy and cosmology. The particle spectrum is reviewed and the issues of gauge coupling unification, dilaton stabilization and modular cosmology are discussed. A specific model for condensation and supersymmetry breaking, that respects known constraints from string theory and is phenomenologically viable, is described.Comment: 24 pages, talk presented at The Richard Arnowitt Fest, April 5-8, 1998, Texas A & M University, College Station, TX, to be published in the proceedings, full postscript available from http://phyweb.lbl.gov/theorypapers/preprints.html/41110.p

Pauli-Villars Regularization of Supergravity and Field Theory Anomalies

A procedure for Pauli-Villars regularization of locally and globally supersymmetric theories is described. Implications for specific theories, especially those obtained from superstrings, are discussed with emphasis on the role of field theory anomalies.Comment: 8 pages, Talk given at SUSY95, l'Ecole Polytechnique, Palaiseau, France, May 15-19, 199

T-duality and the weakly coupled heterotic string

T-duality is a symmetry of the heterotic string to all orders in string perturbation theory. This results in an effective four dimensional supergravity theory with desirable features for phenomenology. T-duality, as well as, generically, an anomalous U(1), is broken by quantum anomalies of the effective field theory. The structure of the full anomaly is presented, and the mechanisms for anomaly cancellation are described.Comment: 12 pages, plenary talk at SUSY09, to appear in the proceeding

Quantum supergravity, supergravity anomalies and string phenomenology

I discuss the role of quantum effects in the phenomenology of effective supergravity theories from compactification of the weakly coupled heterotic string. An accurate incorporation of these effects requires a regularization procedure that respects local supersymmetry and BRST invariance and that retains information associated with the cut-off scale, which has physical meaning in an effective theory. I briefly outline the Pauli-Villars regularization procedure, describe some applications, and comment on what remains to be done to fully define the effective quantum field theory.Comment: 30 pages, to be published in a memorial volume for Raymon

Supergravity Coupled to Chiral Matter at One Loop

We extend earlier calculations of the one-loop contributions to the effective bose Lagrangian in supergravity coupled to chiral matter. We evaluate all logarithmically divergent contributions for arbitrary background scalar fields and space-time metric. We show that, with a judicious choice of gauge fixing and of the definition of the action expansion, much of the result can be absorbed into a redefinition of the metric and a renormalization of the K\"ahler potential. Most of the remaining terms depend on the curvature of the K\"ahler metric. Further simplification occurs in models obtained from superstrings in which the K\"ahler Riemann tensor is covariantly constant.Comment: 33 pages, LBL-34457, UCB-PTH-93-2

The Anomaly Structure of Regularized Supergravity

On-shell Pauli-Villars regularization of the one-loop divergences of supergravity theories is used to study the anomaly structure of supergravity and the cancellation of field theory anomalies under a $U(1)$ gauge transformation and under the T-duality group of modular transformations in effective supergravity theories with three K\"ahler moduli $T^i$ obtained from orbifold compactification of the weakly coupled heterotic string. This procedure requires constraints on the chiral matter representations of the gauge group that are consistent with known results from orbifold compactifications. Pauli-Villars regulator fields allow for the cancellation of all quadratic and logarithmic divergences, as well as most linear divergences. If all linear divergences were canceled, the theory would be anomaly free, with noninvariance of the action arising only from Pauli-Villars masses. However there are linear divergences associated with nonrenormalizable gravitino/gaugino interactions that cannot be canceled by PV fields. The resulting chiral anomaly forms a supermultiplet with the corresponding conformal anomaly, provided the ultraviolet cut-off has the appropriate field dependence, in which case total derivative terms, such as Gauss-Bonnet, do not drop out from the effective action. The anomalies can be partially canceled by the four-dimensional version of the Green-Schwarz mechanism, but additional counterterms, and/or a more elaborate set of Pauli-Villars fields and couplings, are needed to cancel the full anomaly, including D-term contributions to the conformal anomaly that are nonlinear in the parameters of the anomalous transformations.Comment: 103 page

S-Duality Constraints On Effective Potentials For Gaugino Condensation

We clarify the role of approximate S-duality in effective supergravity theories that are the low energy limits of string theories, and show how this partial symmetry may be used to constrain effective lagrangians for gaugino condensation.Comment: 22 page

Comment on ``Inflation and flat directions in modular invariant superstring effective theories''

The inflation model of Gaillard, Lyth and Murayama is revisited, with a systematic scan of the parameter space for dilaton stabilization during inflation.Comment: 7 pages, 2 figure