Within of the framework of semiclassical approximation a general formalism for deriving an effective current generating bremsstrahlung of arbitrary number of soft gluons (longitudinal or transverse ones) in scattering of higher-energy parton off thermal parton in hot quark-gluon plasma with subsequent extension to two and more scatterers, is obtained. For the case of static color centers an expression for energy loss induced by usual bremsstrahlung of lowestorder with allowance for an effective temperature-induced gluon mass and finite mass of the projectile (heavy quark), is derived. The detailed analysis of contribution to radiation energy loss associated with existence of effective three-gluon vertex induced by hot QCD medium, is performed. It is shown that in general, the bremsstrahlung associated with this vertex have no sharp direction (as in the case of usual bremsstrahlung) and therefore here, we can expect an absence of suppression effect due to multiple scattering. For the case of two color static scattering centers it was shown that the problem of calculation of bremsstrahlung induced by four-gluon hard thermal loop (HTL) vertex correction can be reduced to the problem of the calculation of bremsstrahlung induced by three-gluon HTL correction. It was shown that for limiting value of soft gluon occupation number N k ∼ 1/α s all higher processes of bremsstrahlung of arbitrary number of soft gluons become of the same order in coupling, and the problem of resummation of all relevant contributions to radiation energy loss of fast parton, arises. An explicit expression for matrix element of two soft gluon bremsstrahlung in small angles approximation is obtained. *

In a general line with our first work [1], within hard thermal loop (HTL) approximation a general theory of the scattering for an arbitrary number of colorless plasmons off hard thermal particles of hot QCD-medium is considered. Using generalized Tsytovich correspondence principle, a connection between matrix elements of the scattering processes and a certain effective current, generating these processes is established. The iterative procedure of calculation of these matrix elements is defined, and a problem of their gaugeinvariance is discussed. An application of developed theory to a problem of calculating energy losses of energetic color particle propagating through QCD-medium is considered. It is shown that for limiting value of the plasmon occupation number (∼ 1/g 2 , where g is a strong coupling) energy losses caused by spontaneous scattering process of energetic particle off soft-gluon waves is of the same order in the coupling as other known losses type: collision and radiation ones. The Fokker-Planck equation, describing decceleration (acceleration) and diffusion in momentum space of beam of energetic color particles scattering off soft excitations of quark-gluon plasma (QGP), is derived. *

In general line with our early works [Yu.A. Markov, M.A. Markova, Nucl. Phys. A770 (2006) 162; 784 (2007) 443] within the framework of a semiclassical approximation the general theory of calculation of effective currents and sources generating bremsstrahlung of an arbitrary number of soft quarks and soft gluons at collision of a high-energy color-charged particle with thermal partons in a hot quark-gluon plasma, is developed. For the case of one-and two-scattering thermal partons with radiation of one or two soft excitations, the effective currents and sources are calculated in an explicit form. In the model case of 'frozen' medium, approximate expressions for energy losses induced by the most simple processes of bremsstrahlung of soft quark and soft gluon, are derived. On the basis of a conception of the mutual cancellation of singularities in the sum of so-called 'diagonal' and 'off-diagonal' contributions to the energy losses, an effective method of determining color factors in scattering probabilities, containing the initial values of Grassmann color charges, is suggested. The dynamical equations for Grassmann color charges of hard particle used by us early are proved to be insufficient for investigation of the higher radiative processes. It is shown that for correct description of these processes the given equations should be supplemented successively with the higher-order terms in powers of the soft fermionic field. *

The first study of quasi-free Compton scattering on the neutron in the energy range of Eγ = 0.75 − 1.5 GeV is presented. The data reveals a narrow peak at W ∼ 1.685 GeV. This result, being considered in conjunction with the recent evidence for a narrow structure at W ∼ 1.68 GeV in the η photoproduction on the neutron, suggests the existence of a new nucleon resonance with unusual properties: the mass M ∼ 1.685 GeV, the narrow width Γ ≤ 30 MeV, and the much stronger photoexcitation on the neutron than on the proton. PACS numbers:Many properties of known baryons were transparently explained by the constituent quark model(CQM) [1] that treats baryons as bound system of three valence quarks in the ground or excited state. Some baryon properties remain a mystery: almost half of the CQM-predicted nucleon and ∆ resonances [2] still escape the reliable experimental identification [3] (so-called "missing resonances").The chiral quark soliton model (χQSM) is an alternative view of baryons which are treated as space/flavor rotational excitations of a classical object -a chiral mean-field. χQSM predicts the lowest-mass multiplets of baryons to be the 1/2 + octet and 3/2 + decuplet -exactly as CQM does. The χQSM predictions for higher multiplets are different from CQM [4].Thus, the experimental study of baryon resonances provides benchmark information for the development of theoretical models and for finding relations between them.

The solutions of Heisenberg equations and two-particles eigenvalue problems for nonrelativistic models of current-current fermion interaction and N, Θ model are obtained in the frameworks of dynamical mapping method. The equivalence of different types of dynamical mapping is shown. The connection between renormalization procedure and theory of selfadjoint extensions is elucidated. General considerationThe main problem of QFT follows from the fact that any solutions of Heisenberg equations (HE) are the operator distributions which products, always appearing in that equations, are ill-defined.So, the correct definition of field equations (and Hamiltonian itself) implies some knowledge about qualitative properties of its solutions which in their turn depend on the form of these equations by a very singular manner. The usual way to go out from this closed circle is connected with perturbation theory. It is based on the assumption that product of Heisenberg fields (HF) may be defined as well as for the free ones and solution of HE may be obtained by perturbation in the Fock space of renormalized free fields. However, it is impossible on such a way to work with nonrenormalizable theory and to understand the origin of the bound states. We consider another possibility which is based on the idea of dynamical mapping and reduce the product of HF to the normal ordering for the product of the physical fields. It is originated from the works of R.Haag In this approach the problem of making a sense for formal expression of HF:for Hamiltonian given as a functional H = H [Ψ( x, t)], is divided on two parts. The first one is the construction of the following operator realization of the initial fields Ψ( x, t 0 ) = Ψ[ψ] via physical fields ψ( x, t) ≡ ψ A α ( k) , which, on the one hand, should be consistent with CCR (CAR) (α = 1, 2) {Ψ α ( x, t) , Ψ β ( y, t)} = 0 = {ψ α ( x, t) , ψ β ( y, t)}, {Ψ α ( x, t) , Ψ † β ( y, t)} = δ 3 ( x − y) δ αβ = {ψ α ( x, t) , ψ † β ( y, t)}, {A α ( k) , A β ( q)} = 0; {A α ( k) , A † β ( q)} = δ 3 ( k − q) δ αβ ,