31 research outputs found
Angular Analysis of the B+ -> K*(+)mu(+) mu(-) Decay
We present an angular analysis of the
B
+
→
K
*
+
(
→
K
0
S
π
+
)
μ
+
μ
−
decay using
9
fb
−
1
of
p
p
collision data collected with the LHCb experiment. For the first time, the full set of
C
P
-averaged angular observables is measured in intervals of the dimuon invariant mass squared. Local deviations from standard model predictions are observed, similar to those in previous LHCb analyses of the isospin-partner
B
0
→
K
*
0
μ
+
μ
−
decay. The global tension is dependent on which effective couplings are considered and on the choice of theory nuisance parameters
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Study of the and states in decays
The decays are studied using a data
set corresponding to an integrated luminosity of 9fb collected with the
LHCb detector in proton-proton collisions between 2011 and 2018. Precise
measurements of the ratios of branching fractions with the intermediate
, and states are reported. The decay
of with is observed for the first time with a significance of 5.1
standard deviations. The mass differences between the ,
and states are measured to be resulting in the
most precise determination of the mass. The width of the
state is found to be below 5.2MeV at 90\% confidence level. The
Breit-Wigner width of the state is measured to be which is inconsistent with zero by 5.5 standard deviations
Search for time-dependent violation in and decays
A search for time-dependent violation of the charge-parity symmetry in and decays is performed at the LHCb experiment using proton-proton collision data recorded from 2015 to 2018 at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb. The meson is required to originate from a decay, such that its flavour at production is identified by the charge of the accompanying pion. The slope of the time-dependent asymmetry of the decay rates of and mesons into the final states under consideration is measured to be , , where the first uncertainties are statistical and the second are systematic. These results are compatible with the conservation of the charge-parity symmetry at the level of 2 standard deviations and improve the precision by nearly a factor of two
Assessment of soil tolerance toward contamination with black oil in the south of Russia on the basis of soil biological indices: A model experiment
Silver Ecotoxicity Estimation by the Soil State Biological Indicators
The use of silver in various spheres of life and production leads to an increase in environmental pollution, including soil. At the same time, the environmental consequences of silver pollution of soils have been studied to a much lesser extent than those of other heavy metals. The aim of this study is to estimate silver ecotoxicity using the soil state biological indicators. We studied soils that are significantly different in resistance to heavy metal pollution: ordinary chernozem (Haplic Chernozems, Loamic), sierosands (Haplic Arenosols, Eutric), and brown forest acidic soil (Haplic Cambisols, Eutric). Contamination was simulated in the laboratory. Silver was introduced into the soil in the form of nitrate in doses of 1, 10, and 100 mg/kg. Changes in biological parameters were assessed 10, 30, and 90 days after contamination. Silver pollution of soils in most cases leads to deterioration of their biological properties: the total number of bacteria, the abundance of bacteria of the genus Azotobacter, the activity of enzymes (catalase and dehydrogenases), and the phytotoxicity indicators decrease. The degree of reduction in biological properties depends on the silver concentration in the soil and the period from the contamination moment. In most cases, there is a direct relationship between the silver concentration and the degree of deterioration of the studied soil properties. The silver toxic effect was most pronounced on the 30th day after contamination. In terms of their resistance to silver pollution, the studied soils are in the following order: ordinary chernozem > sierosands ≥ brown forest soil. The light granulometric composition of sierosands and the acidic reaction of the environment of brown forest soils, as well as the low content of organic matter, contribute to high mobility and, consequently, high ecotoxicity of silver in these soils. The regional maximum permissible concentration (rMPC) of silver in ordinary chernozem (Haplic Chernozems, Loamic) is 4.4 mg/kg, in sierosands (Haplic Arenosols, Eutric) 0.9 mg/kg, and in brown forest soils (Haplic Cambisols, Eutric) 0.8 mg/kg
Estimation of Ecotoxicity of Nanoparticles of Cobalt, Copper, Nickel and Zinc Oxides on Biological Indicators of the State of Ordinary Chernozem
Aim. Assessment of the effect of nanoparticles of oxides of cobalt, nickel, copper, zinc on the biological state of ordinary chernozem.Material and Methods. The effect of Co3O4, CuO, NiO and ZnO nanoparticles on the biological properties of soil was studied on ordinary chernozem (Rostov‐on‐Don, ussia). We studied the effect of various concentrations of pollutants depending on their content in soil of 3, 10, 30 backgrounds. Co3O4, CuO, NiO and ZnO nanoparticles with a size of <50 nm and TiO2 of <100 nm.Results. Contamination of ordinary chernozem by Co3O4, CuO, NiO and ZnO and their nanoparticles leads to a deterioration in its biological properties in terms of: total bacteria numbers; abundance of bacteria of the genus Azotobacter; activity of catalase; activity of dehydrogenases and decrease in seed germination and length of radish roots. The oxides of the elements under study had an approximately equal negative effect on these indicators, while among the nanopowders the most toxic were the oxides of copper and zinc and the least was cobalt oxide. It was established that the nanopowders of Co3O4, CuO, NiO, and ZnO reduce the biological indices of ordinary chernozem to a greater extent than the ‘conventional’ forms of oxides. A stimulating effect of the studied substances on the biological properties of ordinary chernozem was not recorded. This indicates a high toxicity of the studied substances, which is also characteristic of nanoparticles of other elements.Conclusion. Contamination by nanoparticles of oxides of cobalt, nickel, copper and zinc has a negative effect on the biological state of chernozem and is more pronounced than contamination by ‘conventional’ forms of these oxides