7 research outputs found
Patterns of remnant discrete symmetries
We analyze patterns of remnant discrete symmetries that arise from U(1)^N
theories by spontaneous breaking. We describe a simple, geometrical way to
understand these patterns and provide methods for identifying the discrete
symmetries and bringing them to the simplest possible form. Applications in GUT
and string model building are briefly discussed.Comment: 14 pages, 2 figures, a related Mathematica package can be downloaded
from http://einrichtungen.physik.tu-muenchen.de/T30e/codes/DiscreteBreaking
Running minimal flavor violation
We consider the flavor structure of the minimal supersymmetric standard model
(MSSM) in the framework of `minimal flavor violation' (MFV). We show that, if
one imposes the MFV structure at some scale, to a good accuracy the MFV
decomposition works at all other scales. That is, quantum effects can be
described by running coefficients of the MFV decomposition. We find that the
coefficients get driven to non-trivial fixed points.Comment: 13 pages, 12 figure
A unique Z_4^R symmetry for the MSSM
We consider the possible anomaly free Abelian discrete symmetries of the MSSM
that forbid the mu-term at perturbative order. Allowing for anomaly
cancellation via the Green-Schwarz mechanism we identify discrete R-symmetries
as the only possibility and prove that there is a unique Z_4^R symmetry that
commutes with SO(10). We argue that non-perturbative effects will generate a
mu-term of electroweak order thus solving the mu-problem. The non-perturbative
effects break the Z_4^R symmetry leaving an exact Z_2 matter parity. As a
result dimension four baryon- and lepton-number violating operators are absent
while, at the non-perturbative level, dimension five baryon- and lepton-number
violating operators get induced but are highly suppressed so that the nucleon
decay rate is well within present bounds.Comment: 6 page
Discrete R symmetries for the MSSM and its singlet extensions
We determine the anomaly free discrete R symmetries, consistent with the
MSSM, that commute with SU(5) and suppress the parameter and nucleon
decay. We show that the order M of such symmetries has to divide 24 and
identify 5 viable symmetries. The simplest possibility is a symmetry
which commutes with SO(10). We present a string-derived model with this
symmetry and the exact MSSM spectrum below the GUT scale; in this model
originates from the Lorentz symmetry of compactified dimensions. We extend the
discussion to include the singlet extensions of the MSSM and find and
are the only possible symmetries capable of solving the problem
in the NMSSM. We also show that a singlet extension of the MSSM based on a
symmetry can provide a simultaneous solution to the and strong
CP problem with the axion coupling in the favoured window.Comment: 44+1 pages, 2 figure