85 research outputs found
Topics in String Unification
I discuss several aspects of strings as unified theories. After recalling the
difficulties of the simplest supersymmetric grand unification schemes I
emphasize the distinct features of string unification. An important role in
constraining the effective low energy physics from strings is played by
symmetries. The discussed topics include the unification of coupling
constants (computation of and at the weak
scale), supersymmetry breaking through gaugino condensation, and properties of
the induced SUSY-breaking soft terms. I remark that departures from
universality in the soft terms are (in contrast to the minimal SUSY model)
generically expected.Comment: 22 pages. Talk given at the ``Workshop on Electroweak Physics Beyond
the Standard Model'', Valencia, 3-5 October 199
The Fluxed MSSM
Recent developemnts in string compactifications in the presence of
antisymmetric field backgrounds suggest a new simple and predictive structure
for soft terms in the MSSM depending only on two parameters. They give rise to
a positive definite scalar potential, a solution to the -problem, flavor
universality and absence of a SUSY-CP problem.Comment: 23 pages, no figures. Addendum on intersecting D7-branes included.
Referencese added and minor change
A Chiral D=4, N=1 String Vacuum with a Finite Low Energy Effective Field Theory
Supersymmetric N=1, D=4 string vacua are known to be finite in perturbation
theory. However, the effective low energy D=4, N=1 field theory lagrangian does
not yield in general finite theories. In this note we present the first (to our
knowledge) such an example. It may be constructed in three dual ways: i) as a
, SO(32) heterotic orbifold; ii) as a Type -IIB, orientifold with
only ninebranes and a Wilson line or iii) as a Type-IIB, orientifold with
only fivebranes. The gauge group is with three chiral generations.
Although chiral, a subsector of the model is continuosly connected to a model
with global N=4 supersymmetry. From the , Type IIB orientifold point of
view the above connection may be understood as a transition of four dynamical
fivebranes from a fixed point to the bulk. The N=1 model is thus also expected
to be S-dual. We also remark that, using the untwisted dilaton and moduli
fields of these constructions as spurion fields, yields soft SUSY-breaking
terms which preserve finiteness even for N=0.Comment: 8 pages, LaTe
The Inflaton as a MSSM Higgs and Open String Modulus Monodromy Inflation
It has been recently pointed out that the polarization BICEP2 results are
consistent with the identification of an inflaton mass m \simeq 10^{13} GeV
with the SUSY breaking scale in an MSSM with a fine-tuned SM Higgs. This
identification leads to a Higgs mass m_h \simeq 126 GeV, consistent with LHC
measurements. Here we propose that this naturally suggests to identify the
inflaton with the heavy MSSM Higgs system. The fact that the extrapolated Higgs
coupling lambda_{SM}\simeq 0 at scales below the Planck scale suggests the
Higgs degrees of freedom could be associated to a Wilson line or D-brane
position modulus in string theory. The Higgs system then has a shift symmetry
and an N=2 structure which guarantees that its potential has an approximate
quadratic chaotic inflation form. These moduli in string compactifications,
being compact, allow for a trans-Planckian inflaton field range analogous to a
version of monodromy inflation.Comment: 6 pages. Misprints corrected, references adde
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