14,609 research outputs found
Physics of Brane Kinetic Terms
Models with extra dimensions may give new effects visible at future
experiments. In these models, bulk fields can develop localized corrections to
their kinetic terms which can modify the phenomenological predictions in a
sizeable way. We review the case in which both gauge bosons and fermions
propagate in the bulk, and discuss the limits on the parameter space arising
from electroweak precision data.Comment: Presented at Matter To The Deepest: Recent Developments In Physics of
Fundamental Interactions, XXVII International Conference of Theoretical
Physics, Ustron 15-21 September 2003, Polan
Bulk fields with brane terms
In theories with branes, bulk fields get in general divergent corrections
localized on these defects. Hence, the corresponding brane terms are
renormalized and should be included in the effective theory from the very
beginning. We review the phenomenology associated to brane kinetic terms for
different spins and backgrounds, and point out that renormalization is required
already at the classical level.Comment: Presented at HEP2003, International Europhysics Conference on High
Energy Physics (July 17-23, 2003) Aachen, German
Observable contributions of new exotic quarks to quark mixing
Models with new vector-like quarks can produce observable quark mixing
effects which are forbidden in the Standard Model. We classify all such models
and write down the effective Lagrangian that results from integrating out the
new quarks. We study the relations between neutral and charged currents and
discuss how to distinguish among the different possibilities.Comment: 15 pages, 1 figure, typos corrected, version to appear in JHE
Bulk Fermions in Warped Models with a Soft Wall
We study bulk fermions in models with warped extra dimensions in the presence
of a soft wall. Fermions can acquire a position dependent bulk Dirac mass that
shields them from the deep infrared, allowing for a systematic expansion in
which electroweak symmetry breaking effects are treated perturbatively. Using
this expansion, we analyze properties of bulk fermions in the soft wall
background. These properties include the realization of non-trivial boundary
conditions that simulate the ones commonly used in hard wall models, the
analysis of the flavor structure of the model and the implications of a heavy
top. We implement a soft wall model of electroweak symmetry breaking with
custodial symmetry and fermions propagating in the bulk. We find a lower bound
on the masses of the first bosonic resonances, after including the effects of
the top sector on electroweak precision observables for the first time, of
m_{KK} \gtrsim 1-3 TeV at the 95% C.L., depending on the details of the Higgs,
and discuss the implications of our results for LHC phenomenology.Comment: 34 pages, 8 figure
Possible duality violations in tau decay and their impact on the determination of alpha_s
We discuss the issue of duality violations in hadronic tau decay. After
introducing a physically motivated ansatz for duality violations, we estimate
their possible size by fitting this ansatz to the tau experimental data
provided by the ALEPH collaboration. Our conclusion is that these data do not
exclude significant duality violations in tau decay. This may imply an
additional systematic error in the value of alpha_s(m_tau), extracted from tau
decay, as large as \delta alpha_s(m_tau) \sim 0.003-0.010 .Comment: 20 pages, 4 figures. Minor fixes in the Appendi
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