714 research outputs found
Effect of including major gene information in mass selection: a stochastic simulation in a small population
Using a system of recurrence equations, best linear unbiased prediction applied to a reduced animal model (RAM) is presented for marker-assisted selection. This approach is a RAM version of the method with the animal model to reduce the number of equations per animal to one. The current RAM approach allows simultaneous evaluation of fixed effects and total additive genetic merit which is expressed as the sum of the additive genetic effects due to quantitative trait loci (QTL) unlinked to the marker locus (ML) and the additive effects due to the QTL linked to the ML. The total additive genetic merits for animals with no progeny are predicted by the formulae derived for backsolving. A numerical example is given to illustrate the current RAM approach.Sur la base d’un système d’équations de récurrence, la méthode du meilleur prédicteur linéaire sans biais appliquée à un modèle animal réduit (MAR) est présentée pour la sélection assistée par marqueur. Cette méthode est une version MAR de celle du modèle animal pour réduire à un le nombre d’équations par animal. Cette méthode MAR permet d’estimer simultanément les effets fixés et la valeur génétique globale, qui est la somme des effets génétiques additifs des locus de caractère quantitatif (QTL) non liés au locus marqueur et des effets additifs des QTL liés au locus marqueur. La valeur génétique globale des animaux sans descendance est prédite par un système d’équations reconstitué à partir du système principal. Un exemple numérique est donné pour illustrer la méthode MAR présentée ici
Skyrmion Multi-Walls
Skyrmion walls are topologically-nontrivial solutions of the Skyrme system
which are periodic in two spatial directions. We report numerical
investigations which show that solutions representing parallel multi-walls
exist. The most stable configuration is that of the square -wall, which in
the limit becomes the cubically-symmetric Skyrme crystal. There is
also a solution resembling parallel hexagonal walls, but this is less stable.Comment: 7 pages, 1 figur
Exploring T and S parameters in Vector Meson Dominance Models of Strong Electroweak Symmetry Breaking
We revisit the electroweak precision tests for Higgsless models of strong
EWSB. We use the Vector Meson Dominance approach and express S and T via
couplings characterizing vector and axial spin-1 resonances of the strong
sector. These couplings are constrained by the elastic unitarity and by
requiring a good UV behavior of various formfactors. We pay particular
attention to the one-loop contribution of resonances to T (beyond the chiral
log), and to how it can improve the fit. We also make contact with the recent
studies of Conformal Technicolor. We explain why the second Weinberg sum rule
never converges in these models, and formulate a condition necessary for
preserving the custodial symmetry in the IR.Comment: 35 pages, 7 figures; v3: refs added, to appear in JHE
On the effect of resonances in composite Higgs phenomenology
We consider a generic composite Higgs model based on the coset SO(5)/SO(4)
and study its phenomenology beyond the leading low-energy effective lagrangian
approximation. Our basic goal is to introduce in a controllable and simple way
the lowest-lying, possibly narrow, resonances that may exist is such models. We
do so by proposing a criterion that we call partial UV completion. We
characterize the simplest cases, corresponding respectively to a scalar in
either singlet or tensor representation of SO(4) and to vectors in the adjoint
of SO(4). We study the impact of these resonances on the signals associated to
high-energy vector boson scattering, pointing out for each resonance the
characteristic patterns of depletion and enhancement with respect to the
leading-order chiral lagrangian. En route we derive the O(p^4) general chiral
lagrangian and discuss its peculiar accidental and approximate symmetries.Comment: v3: a few typos corrected. Conclusions unchange
One Loop Renormalization of the Littlest Higgs Model
In Little Higgs models a collective symmetry prevents the Higgs from
acquiring a quadratically divergent mass at one loop. This collective symmetry
is broken by weakly gauged interactions. Terms, like Yukawa couplings, that
display collective symmetry in the bare Lagrangian are generically renormalized
into a sum of terms that do not respect the collective symmetry except possibly
at one renormalization point where the couplings are related so that the
symmetry is restored. We study here the one loop renormalization of a
prototypical example, the Littlest Higgs Model. Some features of the
renormalization of this model are novel, unfamiliar form similar chiral
Lagrangian studies.Comment: 23 pages, 17 eps figure
Génotype caséine αs1 et sélection des boucs sur descendance dans les races Alpine et Saanen
International audienc
Naturalness bounds in extensions of the MSSM without a light Higgs boson
Adopting a bottom-up point of view, we make a comparative study of the
simplest extensions of the MSSM with extra tree level contributions to the
lightest Higgs boson mass. We show to what extent a relatively heavy Higgs
boson, up to 200-350 GeV, can be compatible with data and naturalness. The
price to pay is that the theory undergoes some change of regime at a relatively
low scale. Bounds on these models come from electroweak precision tests and
naturalness, which often requires the scale at which the soft terms are
generated to be relatively low.Comment: 18 pages, 5 figures. v2: minor revision, added references. v3,v4:
some numerical correction
Hitting sbottom in natural SUSY
We compare the experimental prospects of direct stop and sbottom pair
production searches at the LHC. Such searches for stops are of great interest
as they directly probe for states that are motivated by the SUSY solution to
the hierarchy problem of the Higgs mass parameter - leading to a "Natural" SUSY
spectrum. Noting that sbottom searches are less experimentally challenging and
scale up in reach directly with the improvement on b-tagging algorithms, we
discuss the interplay of small TeV scale custodial symmetry violation with
sbottom direct pair production searches as a path to obtaining strong sub-TeV
constraints on stops in a natural SUSY scenario. We argue that if a weak scale
natural SUSY spectrum does not exist within the reach of LHC, then hopes for
such a spectrum for large regions of parameter space should sbottom out.
Conversely, the same arguments make clear that a discovery of such a spectrum
is likely to proceed in a sbottom up manner.Comment: 18 pages, 8 figures,v2 refs added, JHEP versio
Simple and Realistic Composite Higgs Models in Flat Extra Dimensions
We construct new composite Higgs/gauge-Higgs unification (GHU) models in flat
space that overcome all the difficulties found in the past in attempting to
construct models of this sort. The key ingredient is the introduction of large
boundary kinetic terms for gauge (and fermion) fields. We focus our analysis on
the electroweak symmetry breaking pattern and the electroweak precision tests
and show how both are compatible with each other. Our models can be seen as
effective TeV descriptions of analogue warped models. We point out that, as far
as electroweak TeV scale physics is concerned, one can rely on simple and more
flexible flat space models rather than considering their unavoidably more
complicated warped space counterparts. The generic collider signatures of our
models are essentially undistinguishable from those expected from composite
Higgs/warped GHU models, namely a light Higgs, colored fermion resonances below
the TeV scale and sizable deviations to the Higgs and top coupling.Comment: 30 figures, 9 figures; v2: minor improvements, one reference added,
version to appear in JHE
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