3,736 research outputs found
Quenched and first unquenched lattice HQET determination of the Bs-Meson width difference
We present recent results for the prediction of the Bs lifetime difference
from lattice Heavy Quark Effective Theory simulations. In order to get a
next-to-leading order result we have calculated the matching between QCD and
HQET and the two-loop anomalous dimensions in the HQET for all the \Delta B=2
operators, in particular for the operators which enter the width difference. We
present results from quenched and, for the first time, from unquenched
simulations. We obtain for the Bs lifetime difference,
(\Delta\Gamma_Bs/\Gamma_Bs)^{(que.)}=(5.1+/- 1.9+/- 1.7)10^(-2) and
(\Delta\Gamma_Bs/\Gamma_Bs)^{(unq.)}=(4.3+/- 2.0+/- 1.9)10^(-2) from the
quenched and unquenched simulations respectivelyComment: Lattice 2000 (Heavy Quark Physics), 4 pages, LaTeX. Some misprints
corrected. No result change
Flat tax reforms in the U.S.: A boon for the income poor
In this article we quantify the aggregate, distributional and welfare consequences of
two revenue neutral flat-tax reforms using a model economy that replicates the U.S.
distributions of earnings, income and wealth in very much detail. We find that the less
progressive reform brings about a 2.4 percent increase in steady-state output and a
more unequal distribution of after-tax income. In contrast, the more progressive reform brings about a -2.6 percent reduction in steady-state output and a distribution of aftertax income that is more egalitarian. We also find that in the less progressive flat-tax economy aggregate welfare falls by -0.17 percent of consumption, and in the more
progressive flat-tax economy it increases by 0.45 percent of consumption. In both flattax
reforms the income poor pay less income taxes and obtain sizeable welfare gains
The first INTEGRAL-OMC catalogue of optically variable sources
The Optical Monitoring Camera (OMC) onboard INTEGRAL provides photometry in
the Johnson V-band. With an aperture of 50 mm and a field of view of 5deg x
5deg, OMC is able to detect optical sources brighter than V~18, from a
previously selected list of potential targets of interest. After more than nine
years of observations, the OMC database contains light curves for more than
70000 sources (with more than 50 photometric points each). The objectives of
this work have been to characterize the potential variability of the objects
monitored by OMC, to identify periodic sources and to compute their periods,
taking advantage of the stability and long monitoring time of the OMC. To
detect potential variability, we have performed a chi-squared test, finding
5263 variable sources out of an initial sample of 6071 objects with good
photometric quality and more than 300 data points each. We have studied the
periodicity of these sources using a method based on the phase dispersion
minimization technique, optimized to handle light curves with very different
shapes.In this first catalogue of variable sources observed by OMC, we provide
for each object the median of the visual magnitude, the magnitude at maximum
and minimum brightness in the light curve during the window of observations,
the period, when found, as well as the complete intrinsic and period-folded
light curves, together with some additional ancillary data.Comment: Accepted by Astronomy & Astrophysics; 13 pages, 16 figures. Figures'
resolution has been degraded to fit astro-ph constraint
Prolamin content and grain weight in RNAi silenced wheat lines under different conditions of temperature and nitrogen availability
Temperature and nitrogen (N) availability are two important environmental factors that may produce important changes in grain composition during grain filling of bread wheat. In this study, four wheat lines with the down-regulation of gliadins by means of RNA interference (RNAi) have been characterized to determine the effect of thermal stress and N availability on grain weight and quality; with focus on gliadin and glutenin protein fractions. Grain weight was reduced with heat stress (HS) in all RNAi lines, whereas gliadin content was increased in the wild-types. With respect to gliadin content, RNAi lines responded to HS and N availability differently from their respective wild-types, except for Ï-gliadin content, indicating a very clear stability of silencing under different environmental conditions. In a context of increased temperature and HS events, and in environments with different N availability, the RNAi lines with down-regulated gliadins seem well suited for the production of wheat grain with low gliadin content.The Spanish Ministry of Economy and Competitiveness (Project AGL2016-80566-P) and the European Regional Development Fund (FEDER) supported this research
Isoscaling and the nuclear EOS
Experiments with rare isotopes are shedding light on the role isospin plays
in the equation of state (EoS) of nuclear matter, and isoscaling -an
straight-forward comparison of reactions with different isospin- could deliver
valuable information about it. In this work we test this assertion
pragmatically by comparing molecular dynamics simulations of isoscaling
reactions using different equations of state and looking for changes in the
isoscaling parameters; to explore the possibility of isoscaling carrying
information from the hot-and-dense stage of the reaction, we perform our study
in confined and expanding systems. Our results indicate that indeed isoscaling
can help us learn about the nuclear EoS, but only in some range of excitation
energies
Width difference in the Bs system from lattice HQET
We present recent results for the prediction of the Bs lifetime difference
from lattice Heavy Quark Effective Theory simulations. In order to get a
next-to-leading order result we have calculated the matching between QCD and
HQET and the two loop anomalous dimension in the HQET for all the \Delta B=2
operators, in particular for the operators which enter in the width difference.
We obtain for the Bs lifetime difference, (\Delta\Gamma_Bs/\Gamma_Bs)=(5.1+/-
1.9+/- 1.7)10^(-2).Comment: 4 pages, LaTeX. Talk given at International Conference on Hyperons,
Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 2000. Some misprints
corrected. No result change
Limits to the planet candidate GJ 436c
We report on H-band, ground-based observations of a transit of the hot
Neptune GJ 436b. Once combined to achieve sampling equivalent to archived
observations taken with Spitzer, our measurements reach comparable precision
levels. We analyze both sets of observations in a consistent way, and measure
the rate of orbital inclination change to be of 0.02+/-0.04 degrees in the time
span between the two observations (253.8 d, corresponding to 0.03+/-0.05
degrees/yr if extrapolated). This rate allows us to put limits on the relative
inclination between the two planets by performing simulations of planetary
systems, including a second planet, GJ 436c, whose presence has been recently
suggested (Ribas et al. 2008). The allowed inclinations for a 5 M_E super-Earth
GJ 436c in a 5.2 d orbit are within ~7 degrees of the one of GJ 436b; for
larger differences the observed inclination change can be reproduced only
during short sections (<50%) of the orbital evolution of the system. The
measured times of three transit centers of the system do not show any departure
from linear ephemeris, a result that is only reproduced in <1% of the simulated
orbits. Put together, these results argue against the proposed planet candidate
GJ 436c.Comment: Replaced with accepted version. Minor language corrections. 4 pages,
4 figures, to appear in A&A Letter
CuantificaciĂłn de deformaciones recientes en el este de la PenĂnsula IbĂ©rica mediante la comparaciĂłn de datos de nivelaciĂłn de precisiĂłn
The comparison of the Instituto GeogrĂĄfico Nacional of Spain high precision levelling data measured during the present century allows us to quantify the ve rtical deformations occurred within this period. The vertical displacements are shown as recent ve rtical movement profiles. We studied the eastern Iberian Peninsula due to its historical and instrumental seismicity and because of the presence a moderate tectonic activity. The magnitude of the vertical movements are according to the recent tectonic activity of each zone, thus the greatest deformations are located at the most tectonic active zones. In the central zone (Valencia Through) tectonic deformations are almost inappreciable, but in the northern (Eastern Pyrenees) and southern (Eastern Betics) zones the average vertical velocities range between 1 and 4 mm/year. In the northern zone the ve rtical anomalies are associated with NW-SE and NE-SW faults with a normal component of movement. In the Eastern Betics the anomalies are related to nearly E-W inverse faults and to NE-SW or NW-SE normal faults. These movements agree with the present day stress tensor (NNW-SSE horizontal compression together with ENE-WSW extension). To confirm the obtained results and to have a better understanding on the main active faults we must carry out new levelling lines and more geological studies
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