2,652 research outputs found
B decays in the upsilon expansion
Theoretical predictions for B decay rates are rewritten in terms of the
Upsilon(1S) meson mass instead of the b quark mass, using a modified
perturbation expansion. The theoretical consistency of this expansion is shown
both at low and high orders. Our method improves the behavior of the
perturbation series for semileptonic and nonleptonic inclusive decay modes, as
well as for exclusive decay form factors. The results are applied to the
determination of the semileptonic B branching ratio, charm counting, the ratio
of B -> X tau nu and B -> X e nu decay rates, and form factor ratios in B -> D*
e nu decay. We also comment on why it is not possible to separate perturbative
and nonperturbative effects in QCD.Comment: 21 page
Constraining weak annihilation using semileptonic D decays
The recently measured semileptonic D_s decay rate can be used to constrain
weak annihilation (WA) effects in semileptonic D and B decays. We revisit the
theoretical predictions for inclusive semileptonic D_{(s)} decays using a
variety of quark mass schemes. The most reliable results are obtained if the
fits to B decay distributions are used to eliminate the charm quark mass
dependence, without using any specific charm mass scheme. Our fit to the
available data shows that WA is smaller than commonly assumed. There is no
indication that the WA octet contribution (which is better constrained than the
singlet contribution) dominates. The results constrain an important source of
uncertainty in the extraction of |Vub| from inclusive semileptonic B decays.Comment: 5 pages, 2 figures, published versio
Global analysis of inclusive B decays
In light of the large amount of new experimental data, we revisit the
determination of V_{cb} and m_b from inclusive semileptonic and radiative B
decays. We study shape variables to order lqcd^3/m_b^3 and alpha_s^2\beta_0,
and include the order alpha_s, lqcd/m_b correction to the hadron mass spectrum
in semileptonic decay, which improves the agreement with the data. We focus on
the 1S and kinetic mass schemes for the b quark, with and without expanding
m_b-m_c in HQET. We perform fits to all available data from BABAR, BELLE, CDF,
CLEO, and DELPHI, discuss the theoretical uncertainties, and compare with
earlier results. We find V_{cb} = (41.4 +- 0.6 +- 0.1) x 10^{-3} and m_b^{1S} =
4.68 +- 0.03 GeV, including our estimate of the theoretical uncertainty in the
fit.Comment: 12 pages, 6 figures. Includes latest BELLE data on lepton and hadron
moments. Electromagnetic correction was improperly included in previous
versio
Analysis of pig meat production with respect to different housing systems of pig
The research focused on two production systems of fattening pigs: conventional system (housing on cross - barred floor) and ecological system (housing on deep litter). Favorable climatic conditions for pig meat production, possibilities to produce cheaper food of better quality and great amounts of litter, are a good basis for making ecological pig production widely accepted by family farms. Ecological aspect of such production of pigs, along with its economic analysis will be key factors, which will influence pig producers in their choice of the most suitable technological solution. In comparison to the conventional way of keeping pigs, main advantages of pig housing on deep litter are cheaper building and equipping of pens, better effect on health conditions of pigs, as well as easier manipulating with manure. Following this context, the research objective was to analyze economic indicators of different pig production systems and to compare economic results obtained in conventional and ecological way of pig production. The research aim was to determine economic possibilities and to evaluate results of production systems in question, justifying their economic and social aspects.Economic Analysis, Conventional Production, Ecological Production, Livestock Production/Industries,
A proposal to solve some puzzles in semileptonic B decays
Some long-standing problems in the experimental data for semileptonic b -> c
l nu decay rates have resisted attempts to resolve them, despite substantial
efforts. We summarize the issues, and propose a possible resolution, which may
alleviate several of these tensions simultaneously, including the "1/2 vs. 3/2
puzzle" and the composition of the inclusive decay rate in terms of exclusive
channels.Comment: 5 pages, 4 figure
Sodium-carbonate co-substituted hydroxyapatite ceramics
Powders of sodium-carbonate co-substituted hydroxyapatite, having sodium content in the range of 0.25–1.5 wt.% with a 0.25 wt.% step, were prepared by a precipitation-solid state reaction route. Compacts of the powders were sintered in a CO2 flow (4 mL/min) at 1100 °C for 2 h. The sintered ceramics contained sodium and carbonate ions in the ranges of 0–1.5 wt.% and 1.3–6 wt.%, respectively, which are typical impurity concentrations in biological apatite. A relationship between sodium and carbonate contents and the type of carbonate substitution was found. The total carbonate content progressively increased with the sodium content. The obtained ceramics showed an AB-type carbonate substitution. However, the substitution became more B-type
as the sodium content increased. As a result, the carbonation was almost B-type (94 %) for the highest sodium content (1.5 wt.%)
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