11,878 research outputs found
Flavor changing neutral currents from lepton and B decays in the two Higgs doublet model
Constraints on the whole spectrum of lepton flavor violating vertices are
shown in the context of the standard two Higgs doublet model. The vertex
involving the mixing is much more constrained than the others, and
the decays proportional to such vertex are usually very supressed. On the other
hand, bounds on the quark sector are obtained from leptonic decays of the
mesons and from . We emphasize that
although the mixing restricts severely the
mixing vertex, the upper bound for this vertex could still give a sizeable
contribution to the decay respect to the standard
model contribution, from which we see that such vertex could still play a role
in the phenomenology.Comment: 9 pages, 2 figures, LaTeX2e. Minor typos corrected. References added
and corrected. Introduction change
Analyses of shocked quartz at the global K-P boundary indicate an origin from a single, high-angle, oblique impact at Chicxulub
Accepted versio
Analysis of CMB maps with 2D wavelets
We consider the 2D wavelet transform with two scales to study sky maps of
temperature anisotropies in the cosmic microwave background radiation (CMB). We
apply this technique to simulated maps of small sky patches of size 12.8 \times
12.8 square degrees and 1.5' \times 1.5' pixels. The relation to the standard
approach, based on the cl's is established through the introduction of the
scalogram. We consider temperature fluctuations derived from standard, open and
flat-Lambda CDM models. We analyze CMB anisotropies maps plus uncorrelated
Gaussian noise (uniform and non-uniform) at idfferent S/N levels. We explore in
detail the denoising of such maps and compare the results with other techniques
already proposed in the literature. Wavelet methods provide a good
reconstruction of the image and power spectrum. Moreover, they are faster than
previously proposed methods.Comment: latex file 7 pages + 5 postscript files + 1 gif file; accepted for
publication in A&A
Compact groups from semi-analytical models of galaxy formation -- V: their assembly channels as a function of the environment
We delved into the assembly pathways and environments of compact groups (CGs)
of galaxies using mock catalogues generated from semi-analytical models (SAMs)
on the Millennium simulation. We investigate the ability of SAMs to replicate
the observed CG environments and whether CGs with different assembly histories
tend to inhabit specific cosmic environments. We also analyse whether the
environment or the assembly history is more important in tailoring CG
properties. We find that about half of the CGs in SAMs are non-embedded
systems, 40% are inhabiting loose groups or nodes of filaments, while the rest
distribute evenly in filaments and voids, in agreement with observations. We
observe that early-assembled CGs preferentially inhabit large galaxy systems (~
60%), while around 30% remain non-embedded. Conversely, lately-formed CGs
exhibit the opposite trend. We also obtain that lately-formed CGs have lower
velocity dispersions and larger crossing times than early-formed CGs, but
mainly because they are preferentially non-embedded. Those lately-formed CGs
that inhabit large systems do not show the same features. Therefore, the
environment plays a strong role in these properties for lately-formed CGs.
Early-formed CGs are more evolved, displaying larger velocity dispersions,
shorter crossing times, and more dominant first-ranked galaxies, regardless of
the environment. Finally, the difference in brightness between the two
brightest members of CGs is dependent only on the assembly history and not on
the environment. CGs residing in diverse environments have undergone varied
assembly processes, making them suitable for studying their evolution and the
interplay of nature and nurture on their traits.Comment: 13 pages, 8 figures. Accepted for publication in MNRA
Delta rho pi interaction leading to N* and Delta* resonances
We have performed a calculation for the three body system
by using the fixed center approximation to Faddeev equations, taking the
interaction between and , and, and and
from the chiral unitary approach. We find several peaks in the modulus
squared of the three-body scattering amplitude, indicating the existence of
resonances, which can be associated to known and and baryon states.Comment: Presented at the 21st European Conference on Few-Body Problems in
Physics, Salamanca, Spain, 30 August - 3 September 201
Genome-wide transcription analysis of clinal genetic variation in Drosophila.
Clinal variation in quantitative traits is widespread, but its genetic basis awaits identification. Drosophila melanogaster shows adaptive, clinal variation in traits such as body size along latitudinal gradients on multiple continents. To investigate genome wide transcription differentiation between North and South that might contribute to the clinal phenotypic variation, we compared RNA expression patterns during development of D. melanogaster from tropical northern and temperate southern populations using whole genome tiling arrays. We found that genes that were differentially expressed between the cline ends were generally associated with metabolism and growth, and experimental alteration of expression of a sample of them generally resulted in altered body size in the predicted direction, sometimes significantly so. We further identified the serpent (srp) transcription factor binding sites to be enriched near genes up-regulated in expression in the south. Analysis of clinal populations revealed a significant cline in the expression level of srp. Experimental over-expression of srp increased body size, as predicted from its clinal expression pattern, suggesting that it may be involved in regulating adaptive clinal variation in Drosophila. This study identified a handful of genes that contributed to clinal phenotypic variation through altered gene expression level, yet misexpression of individual gene led to modest body size change
- …