140 research outputs found
Unification without low-energy supersymmetry
Without supersymmetry, the gauge couplings in the standard model with five
Higgs doublets unify around 10^14 GeV. In this case, the trinified model,
SU(3)_C x SU(3)_L x SU(3)_R x Z_3, with the minimal Higgs sector required for
symmetry breaking, is the ideal grand-unified candidate. Small neutrino masses
are generated via a radiative seesaw mechanism, without the need for
intermediate scales, additional Higgs fields, or higher-dimensional operators.
The proton lifetime is above the experimental limits, with the decay modes p ->
\bar\nu K^+ and p -> mu^+ K^0 potentially observable. The split-SUSY version of
the model, with one light Higgs doublet, is equally attractive.Comment: To appear in Proceedings of SUSY06, the 14th International Conference
on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine,
California, 12-17 June 200
Sterile Neutrinos and Global Symmetries
We use an effective-field-theory approach to construct models with naturally
light sterile neutrinos, due to either exact or accidental global symmetries.
The most attractive models we find are based on gauge symmetries, either
discrete or continuous. We give examples of simple models based on Z_N, U(1)',
and SU(2)'.Comment: 8 pages. v2 (as in PRD): minor changes, typos corrected, two refs
adde
Higgs at the Tevatron in Extended Supersymmetric Models
Supersymmetric models with an additional singlet field offer the Higgs boson
the possibility to decay to two pseudoscalars, a. If the mass of these
pseudoscalars is above the b bbar threshold, a -> b bbar is generically the
dominant decay mode. The decay h -> a a -> b bbar b bbar may be seen above
backgrounds at the Tevatron if the Higgs production cross section is enhanced
relative to that of the standard model.Comment: 3 page
Dimension-Five Operators in Grand Unified Theories
Extensions of the standard model with low-energy supersymmetry generically
allow baryon- and lepton-number violating operators of dimension four and five,
yielding rapid proton decay. The dimension-four operators are usually forbidden
by matter parity. We investigate to what extent the appearance of
dimension-five operators at the Planck scale may be constrained by the
different grand-unified gauge groups. Dimension-five operators are suppressed
in models based on E_6 and SU(3)_C x SU(3)_L x SU(3)_R, where four matter
fields do not form a gauge singlet. An intermediate scale offers the
possibility to sufficiently suppress these dimension-five operators.Comment: 4 pages, v3: version to appear in PR
Higher-dimensional operators in SUSY SO(10) GUT models
SO(10) GUT models with only small Higgs fields use higher-dimensional
operators to generate realistic fermion mass matrices. In particular, a Higgs
field in the spinor representation, 16^d_H, acquires a weak scale vev. We
include the weak vev of the corresponding field \bar{16}^u_H and investigate
the effect on two successful models, one by Albright and Barr (AB) and another
by Babu, Pati and Wilczek (BPW). We find that the BPW model is a particular
case within a class of models with identical fermion masses and mixings. In
contrast, we expect corrections to the parameters of AB-type models.Comment: 3 page
Operator Analysis for Proton Decay in SUSY SO(10) GUT Models
Non-renormalizable operators both account for the failure of down quark and
charged lepton Yukawa couplings to unify and reduce the proton decay rate via
dimension-five operators in minimal SUSY SU(5) GUT. We extend the analysis to
SUSY SO(10) GUT models.Comment: Higgs sector clarified, two Refs adde
Naturalness and the Neutrino Matrix
The observed pattern of neutrino mass splittings and mixing angles indicates
that their family structure is significantly different from that of the charged
fermions. We investigate the implications of these data for the fermion mass
matrices in grand unified theories with a type-I seesaw mechanism. We show
that, with simple assumptions, naturalness leads to a strongly hierarchical
Majorana mass matrix for heavy right-handed neutrinos and a partially cascade
form for the Dirac neutrino matrix. We consider various model building
scenarios which could alter this conclusion, and discuss their consequences for
the construction of a natural model. We find that including partially lopsided
matrices can aid us in generating a satisfying model.Comment: Discussion about neutrinoless double beta decay expanded; typos
corrected; references added and update
Trinification, the Hierarchy Problem and Inverse Seesaw Neutrino Masses
In minimal trinification models light neutrino masses can be generated via a
radiative see-saw mechanism, where the masses of the right-handed neutrinos
originate from loops involving Higgs and fermion fields at the unification
scale. This mechanism is absent in models aiming at solving or ameliorating the
hierarchy problem, such as low-energy supersymmetry, since the large
seesaw-scale disappears. In this case, neutrino masses need to be generated via
a TeV-scale mechanism. In this paper, we investigate an inverse seesaw
mechanism and discuss some phenomenological consequences.Comment: 10 pages, 11 figure
Proton Decay in a Consistent Supersymmetric SU(5) GUT Model
It is widely believed that minimal supersymmetric SU(5) GUTs have been excluded by the SuperKamiokande bound for the proton decay rate. In the minimal model, however, the theoretical prediction assumes unification of Yukawa couplings, Y_d=Y_e, which is known to be badly violated. We analyze the implications of this fact for the proton decay rate. In a consistent SU(5) model with higher dimensional operators, where SU(5) relations among Yukawa couplings hold, the proton decay rate can be several orders of magnitude smaller than the present experimental bound
Vorläufiges Wallnöfer-Werkverzeichnis (WallWV)
Eine chronologisch-systematische Aufstellung sämtlicher Werke des Komponisten Adolf Wallnöfer (1854-1946) unter Angabe ihrer Quellen und Drucklegungsdaten zusammengestellt nach Recherchen im Wallnöfer-Familiennachlass in München, der Städtischen Musikbibliothek München und
der Ă–sterreichischen Nationalbibliothek in Wien (Ă–NB
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