arXiv subjects
Publications and source records attributed to A. P. Kobushkin.
We report some highlights from the ARIES APEC workshop on ``Storage Rings and Gravitational Waves'' (SRGW2021), held in virtual space from 2 February to 18 March 2021, and sketch a tentative landscape for using accelerators and associated technologies for the detection or generation of gravitational waves.
We argue that storage rings can be used for the detection of low-frequency gravitational-wave background. We explain the systematic shrinkage of the machine circumference of the storage ring of the SPring-8, observed by Takao and Shimada (Proceedings of EPAC 2000, Vienna, 2000, p.1572), by the influence of the relic gravitational-wave background. We show that the systematic shrinkage of the machine circumference can be explained by a relic gravitational-wave background even if it is treated as a stochastic system incoming on the plane of the machine circumference from all quarters of the Universe. We show that the rate of the systematic shrinkage of the machine circumference does not depend on the radius of the storage ring and it should be universal for storage rings with any radius.
We calculate momentum distributions of neutrons and protons in $^3$He in the framework of a model which includes 3N interactions together with 2N interactions. It is shown that contribution of 3N interactions becomes essential in comparison with contribution coming from 2N interaction for internal momentum in $^3$He $k>$~250~MeV/c. We also compare calculated momentum distribution of protons with so-called empirical momentum distribution of protons extracted from A$(^3\mathrm{He},p)$ breakup cross-sections measured for protons emitted at zero degree. It is concluded that 3N interactions cannot completely explain the disagreement between the available data on the empirical momentum distribution of protons in $^3\mathrm{He}$ and calculations based on 2N interaction, which is observed at high momentum region of the momentum distribution, $k>$~250~MeV/c.
Using a recent parametrization of the fully antisymmetric three-nucleon wave function, based on the Paris and CD-Bonn potentials, we analyze the momentum distributions of constituents in 3He, as well as the spin-dependent observables for (3He,d) and (3He,p) breakup reactions. Special attention is paid to the region of small relative momenta of the 3He constituents, where the single parameter, D_2, has determining role for the spin-dependent observables in the d+p channel. This fact results in some useful relations between experimental observables.
We discuss two-photon exchange (TPE) in elastic electron scattering off the trinucleon systems, 3He and 3H. The calculations are done in the semirelativistic approximation with the trinucleon wave functions obtained with the Paris and CD-Bonn nucleon-nucleon potentials. An applicability area of the model is wide enough and includes the main part of kinematical domain where experimental data exist. All three TPE amplitudes (generalized form factors) for electron 3He elastic scattering are calculated. We find that the TPE amplitudes are few times more significant in the scattring of electrons off 3He then in the electron proton scattering.
We analyze the momentum distributions of constituents in 3He, as well as the spin-dependent observables for (3He,d), (3He,p), and (d,p) breakup reactions. Special attention is paid to the region of small relative momenta of the helium-3 and the deuteron constituents, where a single parameter, D_2, has determining role for the spin-dependent observables. We extract also this parameter for the deuteron, basing on existing data for the tensor analyzing power of this reaction.
It is shown that the amplitude of elastic ed scattering beyond Born approximation contains six generalized form factors, but only three linearly independent combinations of them (generalized charge, quadrupole and magnetic form factors) contribute to the reaction cross section in the second order perturbation theory. We examine two-photon exchange and find that it includes two types of diagrams, when two virtual photons interact with the same nucleon and when the photons interact with different nucleons.We discuss contribution of the two-photon exchange in reaction observables, generalized \mathcal A and \mathcal B structure functions and tensor polarization of the deuteron.
We discuss the elastic ed scattering beyond Born approximation. It is shown that the reaction amplitude contains six generalized form factors, but only three linearly independent combinations of them (we call them generalized charge, quadrupole and magnetic form factors) contribute to the reaction cross section in the second order perturbation theory. We examine two-photon exchange and find that it includes two types of diagrams, when two virtual photons interact with the same nucleon and when the photons interact with different nucleons. Estimations based on nonrelativistic calculations with the deuteron wave function for realistic NN potential show that the main contribution to the generalized charge, quadrupole and magnetic form factors comes from diagrams of the first type.
We discuss effects of two-photon exchange (TPE) in various observables of the elastic ep-scattering. The imaginary part of the TPE amplitude manifests in target and beam normal spin asymmetries. The real part contributes to the cross-section. A model-independent phenomenological analysis of experimental data is performed. Its results are compared with theoretical calculations.
In the framework of Glauber-Sitenko model we calculate contribution of Coulomb interaction in cross-section of A(d,p) reaction at high energy and zero angle. It is demonstrated that such effect significantly increases the differential cross section only at peak, where the proton momentum $p$ is near half of the deuteron momentum $p_d$ in lab. frame, $p \sim \frac12 p_d$. The Coulomb interaction do not change the results in the high momentum region, where quark effects should be taken into account.
We calculate total cross section for production of the $Ξ_{3/2}(1862)$ exotic baryon in $\bar{K}N \to KΞ_{3/2}$ reaction assuming the following spin-parity values of the $Ξ_{3/2}$ baryon 1/2+, 1/2-, 3/2+, 3/2-. We demonstrate that the reaction total cross section strongly depends on the spin of the $Ξ_{3/2}$ baryon.
We provide systematic analysis of the differential cross section of the proton-$^3{\rm He}$ elastic scattering at $θ_{\rm cm}=180^{\circ}$ and at $T_p<700$ MeV. Three mechanisms are discussed: 2N pair exchange in the triplet and singlet spin states, pion exchange and direct mechanism. It is shown that t Tp>150 MeV tree-body structure, including triplet and singlet states of the 2N pair, becomes of great importance for understanding energy dependence of the reaction observables. Prediction for the differential cross section and the polarization correlation $C_{00nn} which can be studied now in experiment are given. PACS number(s): 21.30.Cb, 21.30.-x, 25.40.Cm, 25.55.Ci
Electron-deuteron elastic scattering data ($A(Q^2)$ and $B(Q^2)$ structure functions and polarization observables $t_{20}$, $t_{21}$ and $t_{22}$) are fit with a model that respects asymptotic properties of pQCD at high momentum transfer. The data analysis shows that pQCD starts from $Q^2=3.5 \rm (GeV/c)^2$. Predictions for the magnetic structure function $B(Q^2)$ and the polarization observables at high momentum transfer are given.
It is considered how spin-orbit potential for two nucleons is changed when one of them is imbedded in nuclear matter. It is emphasized that there appears new tipe of potential antisymmetric under nucleon spins which is proportional to mass difference between free and imbedded nucleons. The longest range behaviour of such potential is estimated.
We study how d+3He beckward elastic scattering is connected with momentum distribution of the deuteron in 3He. With this aim th relativistic calculations in the framework of proton exchange is investigated. We also consider possible reaction mechanisms beyond the proton exchange
We discuss deuteron $A(d,p)X$ breakup and cumulative pion production $A(d,π)X$ in the framework of constituent quark model of the deuteron. We demonstrate that consideration of the Pauli principle at the quark level, as well as multiple scattering, affect drastically cross section and polarization observables of these reactions and provide good description of the experimental data.
We consider properties of narrow baryon states observed recently in reaction $pp\to pπ^+X$. Two lowest of them (with mass 1004 and 1044 MeV, respectively) are stable against strog decay. Moreover we conclude that they cannot decay to $γN$ and thus this states are a kind of metastable levels in quark system. The simplest decay channel is assumed to be $2γN$ and possible quark configuration with such properties is discussed. New experiment for verification of status of this states in $γN$ collision is proposed.
The differential cross section, the tensor analyzing power, $T_{20}$, and the polarization transfer, $κ_0$, in $^{12}C(d,p)$ breakup at relativistic energy are calculated within a model which incorporates multiple scattering and Pauli principle at quark level. It is shown that the rescattering and quark exchange affect drastically the polarization observables for kinematical region corresponding to high internal momentum in the deuteron.