Dispersion relations and subtractions in hard exclusive processes

We study analytical properties of the hard exclusive processes amplitudes. We found that QCD factorization for deeply virtual Compton scattering and hard exclusive vector meson production results in the subtracted dispersion relation with the subtraction constant determined by the Polyakov-Weiss $D$-term. The relation of this constant to the fixed pole contribution found by Brodsky, Close and Gunion and defined by parton distributions is proved, while its manifestation is spoiled by the small $x$ divergence. The continuation to the real photons limit is considered and the numerical correspondence between lattice simulations of $D$-term and low energy Thomson amplitude is found.Comment: 4 pages, journal versio

Helicity-dependent photoabsorption cross sections on the nucleon

We examine the energy dependence of single-meson photoproduction as it contributes to the Gerasimov-Drell-Hearn (GDH) sum rule. For photon energies above approximately 1 GeV, through the full resonance region, this contribution dominates the proton sum rule integral. Over the same energy region, our single-pion contribution to the neutron sum rule also qualitatively follows a recent set of GDH data. The predicted neutral-pion contribution to the neutron sum rule is nearly zero above 1 GeV in this result. The SAID and Mainz (MAID) results are very different for a number of observables over this energy region.Comment: 7 pages, 5 figur

Reciprocal space study of Heisenberg exchange interactions in ferromagnetic metals

The modern quantum theory of magnetism in solids is getting commonly derived using Green's functions formalism. The popularity draws itself from remarkable opportunities to capture the microscopic landscape of exchange interactions, starting from a tight-binding representation of the electronic structure. Indeed, the conventional method of infinitesimal spin rotations, considered in terms of local force theorem, opens vast prospects of investigations regarding the magnetic environment, as well as pairwise atomic couplings. However, this theoretical concept practically does not devoid of intrinsic inconsistencies. In particular, naturally expected correspondence between single and pairwise infinitesimal spin rotations is being numerically revealed to diverge. In this work, we elaborate this question on the model example and canonical case of bcc iron. Our analytical derivations discovered the principal preference of on-site magnetic precursors if the compositions of individual atomic interactions are in focus. The problem of extremely slow or even absent spatial convergence while considering metallic compounds was solved by suggesting the original technique, based on reciprocal space framework. Using fundamental Fourier transform-inspired interconnection between suggested technique and traditional spatial representation, we shed light on symmetry breaking in bcc Fe on the level of orbitally decomposed total exchange surrounding

The Martin boundary of relatively hyperbolic groups with virtually abelian parabolic subgroups

Given a probability measure on a finitely generated group, its Martin boundary is a way to compactify the group using the Green's function of the corresponding random walk. We give a complete topological characterization of the Martin boundary of finitely supported random walks on relatively hyperbolic groups with virtually abelian parabolic subgroups. In particular, in the case of nonuniform lattices in the real hyperbolic space Hn\mathbb{H}^{n}Hn, we show that the Martin boundary coincides with the CAT(0)CAT(0)CAT(0) boundary of the truncated space

Effects of spin polarization on resonant photoemission from d-f states in TbNi2Mnx compounds

Resonant photoemission in narrow-band materials is described by the sum of first-and secondorder transitions, their quantum-mechanical interference leads to an increase in the spectrum from the valence bands and the appearance of an asymmetric dependence on the photon energy. These effects are studied theoretically and experimentally using the example of three-component intermetallic compounds TbNi2Mnx. The competition between the elastic and inelastic photoemission channels leads to a different dependence of photoemission spectra from nickel and manganese on photon energy. The elastic channel is realized on atoms with large magnetic moments, the inelastic Auger decay occurs on atoms with small moments. © 2018 The Authors, published by EDP Sciences.The research was carried out within the state assignment of FASO of Russia (theme uQ" ant" No. 01201463332), supported in part by RFBR (No. 18-02-00060) and UD RAS (No.15 -8 2-10). The authors express their gratitude to A. Preobrazhenskii and N. Vinogradov (synchrotron MAX-Lab, Lund, Sweden) for their assistance in carrying out experiments

Non-autonomous Hamiltonian systems related to highest Hitchin integrals

We describe non-autonomous Hamiltonian systems coming from the Hitchin integrable systems. The Hitchin integrals of motion depend on the W-structures of the basic curve. The parameters of the W-structures play the role of times. In particular, the quadratic integrals dependent on the complex structure (W_2-structure) of the basic curve and times are coordinate on the Teichmuller space. The corresponding flows are the monodromy preserving equations such as the Schlesinger equations, the Painleve VI equation and their generalizations. The equations corresponding to the highest integrals are monodromy preserving conditions with respect to changing of the W_k-structures (k>2). They are derived by the symplectic reduction from the gauge field theory on the basic curve interacting with W_k-gravity. As by product we obtain the classical Ward identities in this theory.Comment: 21 pages,Latex, Contribution in the Proceedings "International Seminar on Integrable systems". In memoriam Mikail V. Saveliev. Bonn, February, 199

Motivation cadets and students of educational institutions dependent on the Russian Interior Ministry in sports

As we know, human health - this is the largest value that can exist on earth. In order to constantly keep yourself in good shape should put a lot of effort to set specific goals and strive to achieve their speedyКак известно, здоровье человека – эта самая большая ценность, которая может существовать на земле. Для того чтобы постоянно поддерживать себя в отличной физической форме необходимо прилагать массу усилий, ставить перед собой определенные цели и стремиться к их скорейшему достижени

Contact types hierarchy and its object-oriented implementation

Technology of the object-oriented implementation for the multibody dynamics models is the key feature when developing the corresponding computer structures. We are based on an approach originating from concepts explained earlier. Following the guidelines outlined there one can develop the family of the constraint abstractions being adapted to any type of the machinery applications and relatively easily implement corresponding family of Modelica models. One also can reorder these classes hierarchically using sequences of the behaviour inheritance. Solutions concerning contact problems and corresponding examples are under consideration