5,683 research outputs found
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 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
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
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
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
Anomaly Structure of Supergravity and Anomaly Cancellation
We display the full anomaly structure of supergravity, including new D-term
contributions to the conformal anomaly. This expression has the super-Weyl and
chiral U(1)_K transformation properties that are required for implementation of
the Green-Schwarz mechanism for anomaly cancellation. We outline the procedure
for full anomaly cancellation. Our results have implications for effective
supergravity theories from the weakly coupled heterotic string theory.Comment: 8 page
Quantum-Induced Soft Supersymmetry Breaking In Supergravity
We calculate the one-loop quantum contributions to soft supersymmetry
breaking terms in the scalar potential in supergravity theories regulated \`a
la Pauli-Villars. We find ``universal'' contributions, independent of the
regulator masses and tree level soft supersymmetry breaking, that contribute
gaugino masses and A-terms equal to the ``anomaly mediated'' contributions
found in analyses using spurion techniques, as well as a scalar mass term not
identified in those analyses. The universal terms are in general modified --
and in some cases canceled -- by model-dependent terms. Under certain
restrictions on the couplings we recover the one-loop results of previous
``anomaly mediated'' supersymmetry breaking scenarios. We emphasize the model
dependence of loop-induced soft terms in the potential, which are much more
sensitive to the details of Planck scale physics then are the one-loop
contributions to gaugino masses. We discuss the relation of our results to
previous analyses.Comment: 18 pages. This replacement corrects eqs. (7) and (31) and adds
clarifying comments after eq. (11) and before eq. (18
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 gauge
transformation and under the T-duality group of modular transformations in
effective supergravity theories with three K\"ahler moduli 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
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