1,733 research outputs found

### Metric on a Statistical Space-Time

We introduce a concept of distance for a space-time where the notion of point
is replaced by the notion of physical states e.g. probability distributions. We
apply ideas of information theory and compute the Fisher information matrix on
such a space-time. This matrix is the metric on that manifold. We apply these
ideas to a simple model and show that the Lorentzian metric can be obtained if
we assumed that the probability distributions describing space-time
fluctuations have complex values. Such complex probability distributions appear
in non-Hermitian quantum mechanics.Comment: 7 page

### Differential Entropy on Statistical Spaces

We show that the previously introduced concept of distance on statistical
spaces leads to a straightforward definition of differential entropy on these
statistical spaces. These spaces are characterized by the fact that their
points can only be localized within a certain volume and exhibit thus a feature
of fuzziness. This implies that Riemann integrability of relevant integrals is
no longer secured. Some discussion on the specialization of this formalism to
quantum states concludes the paper.Comment: 4 pages, to appear in the proceedings of the joint meeting of the 2nd
International Conference on Cybernetics and Information Technologies, Systems
and Applications (CITSA 2005) and the 11th International Conference on
Information Systems Analysis and Synthesis (ISAS 2005), to be held in
Orlando, USA, on July 14-17, 200

### Minimal Grand Unification Model in an Anthropic Landscape

It has been recently pointed out by Arkani-Hamed and Dimopoulos that if the
universe is a landscape of vacua, and if therefore fine-tuning is not a valid
guidance principle for searching for physics beyond the standard model,
supersymmetric unification only requires the fermionic superpartners. We argue
that in that landscape scenario, the fermionic superpartners are not needed for
unification, which can be achieved in SO(10) either via a direct breaking to
the standard model at the grand unification scale or through an intermediate
gauge symmetry. In most minimal SO(10) models, the proton lifetime is long
enough to avoid the experimental bounds. These models are the truly minimal
fine-tuned extensions of the standard model in the sense proposed by Davoudiasl
et al..Comment: 11 page

### Gravitational Corrections to Fermion Masses in Grand Unified Theories

We reconsider quantum gravitational threshold effects to the unification of
fermion masses in Grand Unified Theories. We show that the running of the
Planck mass can have a sizable effect on these thresholds which are thus much
more important than naively expected. These corrections make any extrapolation
from low energy measurements challenging.Comment: 7 page

### Grand Unification on Noncommutative Spacetime

We compute the beta-functions of the standard model formulated on a
noncommutative spacetime. If we assume that the scale for spacetime
noncommutativity is of the order of 2.2 \times 10^{15} GeV we find that the
three gauge couplings of the standard model merge at a scale of 2.3 \times
10^{17} GeV. The proton lifetime is thus much longer than in conventional
unification models.Comment: 6 pages, published versio

### Primordial Black Holes and a Large Hidden Sector

In this note we point out that primordial black holes could be much shorter
lived than usually assumed if there is a large hidden sector of particles that
only interacts gravitationally with the particles of the standard model. The
observation of the explosion of one of these black holes would severely
constrain the energy scale at which gravity becomes strong.Comment: 6 page

### Asymptotically safe weak interactions

We emphasize that the electroweak interactions without a Higgs boson are very
similar to quantum general relativity. The Higgs field could just be a dressing
field and might not exist as a propagating particle. In that interpretation,
the electroweak interactions without a Higgs boson could be renormalizable at
the non-perturbative level because of a non-trivial fixed point. Tree-level
unitarity in electroweak bosons scattering is restored by the running of the
weak scale.Comment: 7 page

### Radiative Lepton Decays and the Substructure of Leptons

The leptons are viewed as composite objects, exhibiting anomalous magnetic
moments and anomalous flavor-changing transition moments. The decay \mu \to e
\gamma is expected to occur with a branching ratio of the same order as the
present experimental limit. The first order QED radiative correction is
considered.Comment: 5 pages, to appear in the proceedings of the International
Europhysics Conference on High Energy Physics, July 12-18 2001, Budapes

### Seesaw induced Higgs Mechanism

We discuss a two scalar doublets model which induces the Higgs mechanism by
means of a seesaw mechanism. This model naturally predicts a light Higgs scalar
whose mass is suppressed by the grand unification scale. The model predicts an
intermediate scale between the electroweak symmetry breaking scale and the
grand unification scale at $10^9$ GeV. Below this intermediate energy scale the
usual standard model appears as an effective theory. A seesaw mechanism in the
scalar sector of the model not only induces the standard Higgs mechanism, but
also solves the hierarchy problem. An implementation of this mechanism in
models where the Planck scale is in the TeV region is discussed.Comment: 4 page

- â€¦