11,878 research outputs found

    Flavor changing neutral currents from lepton and B decays in the two Higgs doublet model

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    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 eτe-\tau 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 Bd,s0B_{d,s}^{0} mesons and from ΔMBd0\Delta M_{B_{d}^{0}}. We emphasize that although the Bd0Bˉd0B_{d}^{0}-\bar{B}_{d}^{0} mixing restricts severely the % d-b mixing vertex, the upper bound for this vertex could still give a sizeable contribution to the decay Bd0μμˉB_{d}^{0}\to \mu \bar{\mu} 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

    Analysis of CMB maps with 2D wavelets

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    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

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    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

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    We have performed a calculation for the three body Δρπ\Delta \rho \pi system by using the fixed center approximation to Faddeev equations, taking the interaction between Δ\Delta and ρ\rho, Δ\Delta andπ\pi, and ρ\rho and π\pi 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 I=1/2,3/2I=1/2, 3/2 and JP=1/2+,3/2+J^P=1/2^+, 3/2^+ and 5/2+5/2^+ 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.

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    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
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