1,591 research outputs found
Little Higgs and precision electroweak tests
I consider the low energy limit of Little Higgs models. The method consists
in eliminating the heavy fields using their classical equations of motion in
the infinite mass limit. After the elimination of the heavy degrees of freedom
one can directly read off deviations from the precision electroweak data. I
also examine the effects on the low energy precision experiments.Comment: Talk given at 39th Rencontres de Moriond on Electroweak Interactions
and Unified Theories, La Thuile, Italy, 21-28 Mar 200
Charged Higgs in Models with Singlet Neutrino in Large Extra Dimensions
The charged Higgs decay in the channel H^- ->tau_L^- nu in models with a
singlet neutrino can provide a test of large extra dimensions models with TeV
scale quantum gravity since in the standard two Higgs doublet model type II,
H^- -> tau_L^- nu is suppressed. In the present study, we focus on the decay
H^- -> tau_L^- nu at the LHC for Higgs masses larger than the top-quark mass.Comment: 4 pages, LaTeX2e, 2 figures, 2 tables, Talk given at XXXVIIth
Rencontres de Moriond, ElectroWeak Interactions and Unified Theories, March
9th - 16th 2002, Les Arcs, Franc
A quark loop model for heavy mesons
I consider a model based on a quark--meson interaction Lagrangian. The
transition amplitudes are evaluated by computing diagrams in which heavy and
light mesons are attached to quark loops. The light chiral symmetry relations
and the heavy quark spin-flavour symmetry dictated by the heavy quark effective
theory are implemented. The model allows to compute the decay form factors and
therefore can give predictions for the decay rates, the invariant mass spectra
and the asymmetries.Comment: 6 pages, 2 tables, LaTeX (aipproc style), Invited talk at QCD@Work,
Martina Franca, Italy, June 16-20 200
Production and decay of gluino pairs at hadron colliders
At hadron colliders, one of the most important channels for sparticle
production is expected to be the gluino pair production. In the scenario where
the sbottom is lighter than the gluino, gluinos can decay into sbottom and
bottom quarks. Sbottoms can subsequently decay into bottom quarks and
neutralinos. Hence, one expects a rich signature consisting of four b-jets and
the missing transverse energy from neutralinos. To compute the cross section of
this reaction, it is important to find tools and techniques suitable for the
calculation of diagrams with many particles in the final state. We present here
a way to deal with such complicated reactions.Comment: Proceedings of the Conference: "QCD and High Energy Hadronic
Interactions", XXXXth Rencontres de Moriond, La Thuile, Italy - March 12-19,
2005 - 4 pages. References update
Multi-tops at the LHC
The experiments at the LHC are searching for many different final states that
can hint to the presence of new physics beyond the Standard Model. One of the
most interesting and promising sectors for these searches is that of the top
quark, for both theoretical and phenomenological reasons linked to its large
mass and to its possible special role in the electroweak symmetry breaking
sector. We suggest that multi-top events, beyond the standard - and
four top searches, can bring further insight in constraining and discovering
physics beyond the Standard Model, taking advantage of experimental techniques
similar to those used in present top-quark analyses. This is relevant both for
the next data taking runs at the LHC and even more at higher luminosity and
higher energy collider options, which are discussed for future LHC upgrades and
future accelerators. In particular we consider six top and eight top final
states, discussing the generic colour representations for beyond the Standard
Model particles giving rise to those final state. We also discuss the limits
which can be extracted by using the present analyses sensitive to four top
final states, as well as the potential bounds from new searches we propose to
experimental collaborations as an alternative.Comment: 16 page
B->rho pi decays, resonant and nonresonant contributions
We point out that a new contribution to B decays to three pions is relevant
in explaining recent data from the CLEO and BABAR collaborations, in particular
the results on quasi-two-body decays via a rho meson. We also discuss the
relevance of these contribution to the measurement of CP violations.Comment: 5 pages, 2 figures, few references and minor comments adde
B0bar decays to D(*)0 eta and D(*)0 eta'
We consider the hadronic B decays B0bar -> D0 eta, B0bar -> D*0 eta, B0bar ->
D0 eta', B0bar -> D*0 eta' in the framework of a quark-flavour basis and
factorization. The formalism allows to compute the decays to the eta meson and
to relate them to those of the eta'. Measuring the branching ratios of these
processes may shed light on the nature of the eta-eta' mixing. On the
experimental side, only upper limits on the branching ratios are known at
present.Comment: 12 pages, 2 figures, 2 tables (LaTeX, revtex), minor revision: note
added at the end concerning new data and few reference
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