33,194 research outputs found
New Physics and novel Higgs signals
We review some of the results of our recent work dealing with the novel type
of Higgs signals that arise when one considers extensions of the standard
model.
We discuss first possible deviations on the Higgs couplings due to heavy
particles, in the context of the MSSM and with large extra-dimensions. Then, we
present several models where it is possible to induce flavor violating Higgs
couplings, and probe them at future hadron colliders through the LFV Higgs
decay h-> tau mu or with rare top decays.Comment: Talk given at the X Mexican School of Particles and Fields, Playa del
Carmen, Mexico, 200
Nonhyperbolic step skew-products: Ergodic approximation
We study transitive step skew-product maps modeled over a complete shift of
, , symbols whose fiber maps are defined on the circle and have
intermingled contracting and expanding regions. These dynamics are genuinely
nonhyperbolic and exhibit simultaneously ergodic measures with positive,
negative, and zero exponents.
We introduce a set of axioms for the fiber maps and study the dynamics of the
resulting skew-product. These axioms turn out to capture the key mechanisms of
the dynamics of nonhyperbolic robustly transitive maps with compact central
leaves.
Focusing on the nonhyperbolic ergodic measures (with zero fiber exponent) of
these systems, we prove that such measures are approximated in the weak
topology and in entropy by hyperbolic ones. We also prove that they are in the
intersection of the convex hulls of the measures with positive fiber exponent
and with negative fiber exponent. Our methods also allow us to perturb
hyperbolic measures. We can perturb a measure with negative exponent directly
to a measure with positive exponent (and vice-versa), however we lose some
amount of entropy in this process. The loss of entropy is determined by the
difference between the Lyapunov exponents of the measures.Comment: 43 pages, 5 figure
Top-Quark FCNC Decay t->cgg in Topcolor-assisted Technicolor Model
The topcolor-assisted technicolor (TC2) model predicts several pseudo-scalars
called top-pions and at loop level they can induce the FCNC top quark decay
t->cgg which is extremely suppressed in the Standard Model (SM). We find that
in the allowed parameter space the TC2 model can greatly enhance such a FCNC
decay and push the branching ratio up to 10^{-3}, which is much larger than the
predictions in the SM (10^{-9}) and in the minimal supersymmetric model
(10^{-4}). We also compare the result with the two-body FCNC decay t-> cg and
find that the branching ratio of t-> cgg is slightly larger than t-> cg. Such
enhanced FCNC top quark decays may serve as a good probe of TC2 model at the
future top quark factory.Comment: 11 pages, 4 figure
Hyperon ordering in neutron star matter
We explore the possible formation of ordered phases in neutron star matter.
In the framework of a quantum hadrodynamics model where neutrons, protons and
Lambda hyperons interact via the exchange of mesons, we compare the energy of
the usually assumed uniform, liquid phase, to that of a configuration in which
di-lambda pairs immersed in an uniform nucleon fluid are localized on the nodes
of a regular lattice. The confining potential is calculated self-consistently
as resulting from the combined action of the nucleon fluid and the other
hyperons, under the condition of beta equilibrium. We are able to obtain stable
ordered phases for some reasonable sets of values of the model parameters. This
could have important consequences on the structure and cooling of neutron
stars.Comment: 6 pages, 2 figures. To appear in the proceedings of the 4th Catania
Relativistic Ion Studies: Exotic Clustering (CRIS 2002), Catania, Italy,
10-14 Jun 200
Rare top decay t-> c l+l- as a probe of new physics
The rare top decay t-> c l+l-, which involves flavor violation, is studied as
a possible probe of new physics. This decay is analyzed with the simplest
Standard Model extensions with additional gauge symmetry formalism. The
considered extension is the Left-Right Symmetric Model, including a new neutral
gauge boson Z' that allows to obtain the decay at tree level through Flavor
Changing Neutral Currents (FCNC) couplings. The neutral gauge boson couplings
are considered diagonal but family non-universal in order to induce these FCNC.
We find the $BR(t-> c l+l-)~10^{-13} for a range 1 TeV < M_{Z'} < 3 TeV.Comment: 9 pages, 6 figure
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