We have reconsidered the results on the masses of the narrow bottomonium states ϒ(1S)–ϒ(3S) obtained in 1982–1986 at CESR, DORIS and VEPP-4 colliders in order to fix shortcomings of the mass ...determination procedures. For experiments at CESR and DORIS this includes the incorrect accounting of the radiative corrections and usage of the electron mass value revised in 1986. In analyses of all experiments the interference of the resonance production and the nonresonant process was ignored. The corrected mass values for five experiments are suggested. The corrections vary from 0.1 to 0.4 MeV. The discrepancy between CESR and VEPP-4 results on ϒ(1S) mass has been reduced from 3.3 to 1.8 standard deviations.
The title compounds, AnO2(H2O)5 n +, n = 1 or 2 and An = U, Np, and Pu, are studied using relativistic density functional theory (DFT). Three rather different relativistic methods are used, ...small-core effective core potentials (SC-ECP), a scalar four-component all-electron relativistic method, and the zeroeth-order regular approximation. The methods provide similar results for a variety of properties, giving confidence in their accuracy. Spin-orbit and multiplet corrections to the AnVI/AnV reduction potential are added in an approximate fashion but are found to be essential. Bulk solvation effects are modeled with continuum solvation models (CPCM, COSMO). These models are tested by comparing explicit (cluster), continuum, and mixed cluster/continuum solvation models as applied to various properties. The continuum solvation models are shown to accurately account for the effects of the solvent, provided that at least the first coordination sphere is included. Reoptimizing the structures in the presence of the bulk solvent is seen to be important for the equatorial bond lengths but less relevant for energetics. Explicit inclusion of waters in the second coordination sphere has a modest influence on the energetics. For the first time, free energies of solvation are calculated for all six AnO2(H2O)5 n + species. The calculated numbers are within the experimental error margins, and the experimental trend is reproduced correctly. By comparison of different relativistic methods, it is shown that an accurate relativistic description leads to marked improvements over the older large-core ECP (LC-ECP) method for bond lengths, vibrational frequencies, and, in particular, the AnVI/AnV reduction potential. Two approximate DFT methods are compared, B3LYP, a hybrid DFT method, and PBE, a generalized gradient approximation. Either method yields AnVI/AnV reduction potentials of comparable quality. Overall, the experimental reduction potentials are accurately reproduced by the calculations.
The available data on the DD‾ and inclusive hadronic cross sections in the ψ(3770) region from the BaBar, Belle, BES-II, CLEO and KEDR experiments have been analyzed assuming that systematic ...uncertainties on cross sections measured by various detectors are not correlated. Four theoretical models predicting the ψ(3770) line shape were considered for the DD‾ channel. All of them gave satisfactory description of the data. The combined analysis of the DD‾ and inclusive hadronic channels was performed using the model based on the vector dominance approach and accounting for the contribution of the ψ(2S) tail to the DD‾ cross section. The following values of the mass, total width, electron width and decay probability to the non-DD‾ states were obtained:M (MeV)Γ (MeV)Γee (eV)BnDD‾3779.8±0.625.8±1.3196±180.164±0.049 where the errors quoted include both statistical and dominant systematic uncertainties.
The geometric structure was determined and the mechanisms of thermal decomposition were studied using the quantum-chemical method of the density functional B3LYP/6-31+G (2df, p) for ...1,1,2,2-tetranitroxyethane and structurally similar 1,2-dinitroxyethane and nitroxyethane molecules: O-N homolytic decomposition, α-elimination of HNO2 and various variants of β-elimination of HNO3. It is established that the radical mechanism is the main channel for the gas-phase decomposition of the studied compounds.
—
The paper presents results of long-term (for seven years) monitoring and analysis of the formation of rainwater acidity in Primorsky Krai, southern Russian Far East. These results reveal the ...variability in the concentrations of both of total dissolved solids (TDS) and individual elements. Two groups of years were distinguished in the general dataset during which the character of the atmospheric circulation played an important role in the ionic balance of the rainwater. The study area was shown to be characterized by predominantly acidic precipitation, with the pH of the water rarely exceeding 5.3 even at low concentrations of strong acid anions. In order to identify the factors that form the acidity of rainwater, the paper proposes to rank the initial dataset according to the value of fractional acidity. In the course of this separation, data blocks with a high and low degree of neutralization of the acid potential are distinguished. Within each data block, the relationships between the pH value and the concentrations of the major ions are defined. During the analysis, it was found that the mechanism of acid rain generation is determined by the mutual influence of natural and human-made sources. It was shown that compounds of dissolved organic carbon (DOC) were involved in both acidification and neutralization of rainwater. The results obtained indicate the predominance of natural rain acidification factors. However, during periods of cyclonic activity, even a slight increase in anthropogenic load leads to an increase in the acidity of atmospheric precipitation to critical values.
Using the 1.32
pb
-
1
statistics collected at the
J
/
ψ
peak with the KEDR detector at the VEPP-4M
e
+
e
-
collider, we measured the branching fractions of
J
/
ψ
meson decays to the final states 2(
π
...+
π
-
)
π
0
,
K
+
K
-
π
+
π
-
π
0
, 2(
π
+
π
-
)
and
K
+
K
-
π
+
π
-
. The results obtained for the decays
J
/
ψ
→
2(
π
+
π
-
)
π
0
,
J
/
ψ
→
K
+
K
-
π
+
π
-
π
0
contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.
Abstract
The mechanisms of the primary act of thermal decomposition of the simplest representative of the series of alkoxy-NNO-azoxy compounds – N-methyl-N’-methoxydiazene-N- oxide are studied using ...quantum-chemical density functional methods PBE, B3LYP, wB97XD with different sets of basic functions, as well as the composite G4 method. It is shown that the most probable channel of its thermal destruction, leading to the formation of experimentally observed reaction products, is isomerization because of rotation of the OCH
3
group around the NO bond with the subsequent transfer of the CH
3
group between oxygen atoms. In this case, the transfer of the CH3 group is the limiting reaction of the thermal decomposition of N-methyl-N’-methoxydiazene-N-oxide as a whole.
Alternative primary reactions of thermal decomposition of
N′
-methoxy-
N
-methyldiazene
N
-oxide (
1
) to the experimentally observed products under normal conditions and the average experimental ...temperature were studied using the density functional methods PBE, B3LYP, wB97XD, wB97X with different basis sets and the composite method G4. All methods gave qualitatively consistent results. Based on these results and a detailed PBE/L11 and B3LYP/6-31G (2df, p) study of various secondary processes, it was concluded that the most energetically advantageous and, hence, the most likely channel of thermal decomposition of
1
involves the isomerization of the latter by rotation of the MeO group around the NO bond followed by the transfer of the Me group between oxygen atoms. The enthalpy of activation of the Me group transfer obtained by all the methods used agrees well with the experimentally obtained value, and this reaction is the limiting step of the entire process of thermal decomposition of
1
.
A method to derive the convenient representations for many two-photon amplitudes is suggested. It is based on the use of the gauge in which the photon propagator has only space components. The ...amplitudes obtained have no any strong numerical cancellations and, therefore, are very convenient for numerical evaluations. Our approach is illustrated by the consideration of the processes e+e−→e+e−e+e−, e+e−→e+e−μ+μ−, and e+e−→μ+μ−π+π−. The method is extended on the case of polarized particles. The amplitudes obtained in this approach have been employed for extension of the event generator developed by F.A. Berends, P.H. Daverveldt, and R. Kleiss. It allows for simulation of e+e−→4l and e+e−→2l2π processes with π+π− pair in the 1−− state with accounting for contributions of narrow vector resonances and ISR corrections. The calculations with arbitrary polarization of initial particles is also foreseen.
Measurement of Γee(J/ψ) with KEDR detector Anashin, V. V; Aulchenko, V. M; Baldin, E. M ...
The journal of high energy physics,
05/2018, Volume:
2018, Issue:
5
Journal Article
Peer reviewed
Open access
A
bstract
The product of the electronic width of the
J/ψ
meson and the branching fractions of its decay to hadrons and electrons has been measured using the KEDR detector at the VEPP-4M
e
+
e
−
...collider. The obtained values are
Γ
e
e
J
/
ψ
=
5.550
±
0.056
±
0.089
keV
,
Γ
e
e
J
/
ψ
·
ℬ
hadrons
J
/
ψ
=
4.884
±
0.048
±
0.078
keV
,
Γ
e
e
J
/
ψ
·
ℬ
e
e
J
/
ψ
=
0.3331
±
0.0066
±
0.0040
keV
.
The uncertainties shown are statistical and systematic, respectively. Using the result presented and the world-average value of the electronic branching fraction, one obtains the total width of the
J/ψ
meson:
Γ
=
92.94
±
1.83
keV
.
These results are consistent with the previous experiments.
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