14,315 research outputs found
Asymptotic safety in higher-derivative gravity
We study the non-perturbative renormalization group flow of higher-derivative
gravity employing functional renormalization group techniques. The
non-perturbative contributions to the -functions shift the known
perturbative ultraviolet fixed point into a non-trivial fixed point with three
UV-attractive and one UV-repulsive eigendirections, consistent with the
asymptotic safety conjecture of gravity. The implication of this transition on
the unitarity problem, typically haunting higher-derivative gravity theories,
is discussed.Comment: 8 pages; 1 figure; revised versio
Conformally reduced quantum gravity revisited
Applying functional renormalization group methods, we describe two
inequivalent ways of defining the renormalization group of matter-coupled four
dimensional gravity, in the approximation where only the conformal factor is
dynamical and taking the trace anomaly explicitly into account. We make contact
with earlier work and briefly discuss the presence or absence of fixed points,
depending on the truncation of the action and other approximations.Comment: 24 page
On the Viability of Minimal Neutrinophilic Two-Higgs-Doublet Models
We study the constraints that electroweak precision data can impose, after
the discovery of the Higgs boson by the LHC, on neutrinophilic
two-Higgs-doublet models which comprise one extra doublet
and a new symmetry, namely a spontaneously broken or a softly
broken global . In these models the extra Higgs doublet, via its very
small vacuum expectation value, is the sole responsible for neutrino masses. We
find that the model with a symmetry is basically ruled out by
electroweak precision data, even if the model is slightly extended to include
extra right-handed neutrinos, due to the presence of a very light scalar. While
the other model is still perfectly viable, the parameter space is considerably
constrained by current data, specially by the parameter. In particular, the
new charged and neutral scalars must have very similar masses.Comment: 22 pages, 3 figures, references and comments added, conclusions
unchanged, matches version to appear in JHE
Coleta transcervical de conceptos bovinos.
Este estudo objstivou avaliar duas técnicas, uma envasiva, para coleta de conceptos bovinos e fluidos do útero, já que o conhecimento da viabilidade do conpto e do microambiente que o mantém são fundamentos para entender e otmizar os processos de reconhecimentos materno e de manutenção da prenhez, componentes importantes da função uterina das vacas
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