Charge-odd and single-spin effects in two-pion production in ep collisions

We consider double-photon and bremsstrahlung mechanisms for the production of two charged pions in high-energy electron (or proton) scattering off a transversely polarised proton. Interference between the relevant amplitudes generates a charge-odd contribution to the cross-section for the process. In the kinematical configuration with a jet nearly collinear to the electron, the spin-independent part may be used to the determine phase differences for pion-pion scattering in states with orbital momentum 0 or 2 and 1, while for the configuration with a jet nearly collinear to the proton, the spin-dependent part may be used to explain the experimental data for single-spin correlations in the production of negatively charged pions. We also discuss the backgrounds and estimate the accuracy of the results to be better than 10 %. In addition, simplified formulae derived for specific kinematics, with small total transverse pion momenta, are given. The accuracy is estimated to remain at the same level despite the lower energy.Comment: 13 pp, LaTeX 2e, uses acromake packag

New Method for Measuring the Ratio μpGE/GM\mu_p G_E/G_M Based on the Polarization Transfer from the Initial Proton to the Final Electron in the ep⃗→e⃗pe \vec p \to \vec e p Process

In this letter, we propose a new method for measuring the Sachs form factors ratio ($R =\mu_p G_E/G_M$) based on the transfer of polarization from the initial proton to the final electron in the elastic $e \vec p \to \vec e p$ process, in the case when the axes of quantization of spins of the target proton at rest and of the scattered electron are parallel, i.e., when an electron is scattered in the direction of the spin quantization axis of the proton target. To do this, in the kinematics of the SANE collaboration experiment (2020) on measuring double spin asymmetry in the $\vec e\vec p \to e p$ process, using Kelly (2004) and Qattan (2015) parametrizations, a numerical analysis was carried out of the dependence of the longitudinal polarization degree of the scattered electron on the square of the momentum transferred to the proton, as well as on the scattering angles of the electron and proton. It is established that the difference in the longitudinal polarization degree of the final electron in the case of conservation and violation of scaling of the Sachs form factors can reach 70%. This fact can be used to set up polarization experiments of a new type to measure the ratio $R$.Comment: 6 pages, 4 figures, 2 tables, for greater clarity, some minor additions have been mad

Surface polaritons at the interface of gyrotropic and nonlinear isotropic media

Surface polaritons at the interface of gyrotropic and non-linear isotropic media are investigated. Dispersion equation and existence conditions for TE surface polariton modes are obtained

Scimago Institutions Rankings for the Assessment of National Education System and Particular University

The article analyzes the results of the Scimago Institutions Rankings for the entire period of its existence and presents the detailed description of the rating methodology and necessary condition for the inclusion in the ranking list, i.e. the publication of more than 100 works by university stuff in the Scopus database. There has been an almost twofold increase in the number of universities in the ten-year ranking lists. The article illustrates the dynamics for a number of countries and analyzes the reasons for their shifts. The competition between China and the United States is demonstrated. It is noted how the adoption of political decisions, such as the “May decrees” in the Russian Federation or projects “211”, “985” in China increase the number of universities in the country participating in the ratings. Such countries as Vietnam, Iran, Indonesia succeeded in multiplying their positions in the university rankings. The article estimates the rate of growth in the number of publications for university in order to maintain its position in the scientometric rankings. The research conducts the analysis of the time required by the ranking agencies to implement and reflect the changes initiated by state competitiveness improvement programs

Surface polaritons in symmetry planes of biaxial crystals

An integral approach is presented in the theory of surface electromagnetic waves propagating along the plane interface of bianisotropic non-absorbing media including optically active gyrotropic and bigyrotropic ones. This approach gives a uniform way of obtaining the dispersion equation for surface polaritons for an arbitrary cut section of the bianisotropic crystals and allows us to establish the existence conditions of surface polaritons. An example of application of this approach for the boundary of bianisotropic and isotropic media is given