We show that the recent experimental data on the cross section of the process
near the threshold can be perfectly explained by the final-state interaction of
and
. The enhancement of the cross ...section is related to the existence of low-energy real or virtual state in the corresponding potential. We present a simple analytical formula that fits the experimental data very well.
A
bstract
Model estimates are obtained for the influence of Coulomb effects on the ratio of the cross sections for the production of charged and neutral
B
B
¯
and
B
*
B
¯
*
pairs in
e
+
e
−
...annihilation. It is shown that the difference between the masses of charged and neutral mesons obtained under the assumption that this ratio is constant on a scale of the order of the beam energy spread can differ from the true one by
δM
∼ 0
.
03 MeV at the energy of Υ(5
S
) and by
δM ∼
0
.
4 MeV at the energy of Υ(4
S
). Thus, the errors given in the PDG for the difference between the masses of charged and neutral
B
mesons, based on the results obtained at the energy of Υ(4
S
), are strongly underestimated. Similar measurements at the energy of Υ(5
S
) will have an order of magnitude smaller systematic shift for the mass difference. This circumstance should be taken into account when planning future experiments at the
B
factory in KEK.
It is shown that an account for the final-state interaction of real or virtual nucleon and antinucleon produced in the processes J/ψ→pp¯γ, ψ(2S)→pp¯γ, J/ψ→pp¯ω, and J/ψ→3(π+π−)γ near the threshold of ...NN¯ pair production allows one to obtain self-consistent description of these processes. Predictions of our model are in good agreement with experimental data available. The proposed potential model also reproduces the corresponding partial cross sections of pp¯ scattering.
The effects of parity violation in the interaction of relativistic polarized protons with
and
nuclei are discussed. Within the Glauber approach, estimates are obtained for
P
-odd asymmetries in the ...total and elastic scattering cross sections, the dissociation cross section, and in the inelastic scattering cross section with meson production. Our calculations show that asymmetry should be most noticeable in the elastic cross section and in the dissociation cross section.
It is shown that the nontrivial energy dependencies of D D ¯ , D D ¯ * , and D * D ¯ * pair production cross sections in e + e − annihilation are well described within the approach based on an ...account of the final-state interaction of produced particles. This statement is valid for the production of charged and neutral particles. Interaction of D ( * ) and D ¯ ( * ) is taken into account using the effective potential method. Its applicability is based on the fact that for near-threshold resonance the characteristic width of peak in the wave function is much larger than the interaction radius. The transition amplitudes between all three channels play an important role in the description of cross sections. These transitions are possible since all channels have the same quantum numbers J P C = 1 − − . Published by the American Physical Society 2024
—
Computer simulations of the DNA damage are widely used due to their large application area. The computational methods to predict DNA breaks are based on molecular concepts about the formation of ...breaks, the geometric structure of DNA, and information about the distribution of absorbed energy in a DNA molecule. Intercomparison of the accuracy of calculations performed by different schemes is commonly difficult, since the calculations employ different prerequisites, postulates, and algorithms. The same applies to determination of the parameters of the DNA lesion models due to scatter of experimental data. A comparative analysis of predictions is performed based on two basic models of the DNA structure, that is, the molecular and volume, which use different assumptions with respect to the formation mechanism of single- and double-strand DNA breaks, in the case of irradiation of DNA molecules with protons and α-particles. Calculations of the efficiency of radiation-induced DNA damage, considering contribution of the direct effect, molecular structure of DNA, and stochastic structure of charged tracks show the dependence of the frequency of occurrence of DNA damage on the model parameters. The parameter domains were found, within which predictions generated by the models are either in agreement or differ from one another.
Bremsstrahlung on noble gases at low energies Milstein, A.I.; Salnikov, S.G.; Kozlov, M.G.
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
11/2022, Letnik:
530
Journal Article
Recenzirano
Odprti dostop
A detailed analysis of the bremsstrahlung spectrum at nonrelativistic electron scattering on argon and xenon is carried out. It is shown that the approximate formulas widely used for the description ...of bremsstrahlung spectra lead to predictions that significantly differ from the exact results. In the limit when the photon frequency tends to zero, a rigorous proof of the relationship between the spectrum of the bremsstrahlung with a transport cross section of electron scattering on an atom is given. This proof does not require any assumptions about the dependence of the scattering phases on energy. For electron energies lower than the luminescence threshold, it is shown that the predictions for a number of radiated photons obtained by the exact formula are in good agreement with the available experimental data.
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