Self-consistent Green function approach for calculations of electronic structure in transition metals

We present an approach for self-consistent calculations of the many-body Green function in transition metals. The distinguishing feature of our approach is the use of the one-site approximation and the self-consistent quasiparticle wave function basis set, obtained from the solution of the Schrodinger equation with a nonlocal potential. We analyze several sets of skeleton diagrams as generating functionals for the Green function self-energy, including GW and fluctuating exchange sets. Their relative contribution to the electronic structure in 3d-metals was identified. Calculations for Fe and Ni revealed stronger energy dependence of the effective interaction and self-energy of the d-electrons near the Fermi level compared to s and p electron states. Reasonable agreement with experimental results is obtained

Transverse-Mass Spectra in Heavy-Ion Collisions at energies E_{lab} = 2--160 GeV/nucleon

Transverse-mass spectra of protons, pions and kaons produced in collisions of heavy nuclei are analyzed within the model of 3-fluid dynamics. It was demonstrated that this model consistently reproduces these spectra in wide ranges of incident energies E_{lab}, from 4A GeV to 160A GeV, rapidity bins and centralities of the collisions. In particular, the model describes the "step-like" dependence of kaon inverse slopes on the incident energy. The key point of this explanation is interplay of hydrodynamic expansion of the system with its dynamical freeze-out.Comment: 13 pages, 16 figures, summary is extended, version accepted by Phys. Rev.

Hydrodynamical description of a hadron-quark first-order phase transition

Solutions of hydrodynamical equations are presented for the equation of state of the Var der Waals type allowing for the first order phase transition. Attention is focused on description of the hadron-quark phase transition in heavy ion collisions. It is shown that fluctuations dissolve and grow as if the fluid is effectively very viscous. Even in spinodal region germs are growing slowly due to viscosity and critical slowing down. This prevents enhancement of fluctuations in the near-critical region, which is frequently considered as a signal of the critical point in heavy ion collisions.Comment: 4 pages, 4 figure

Elliptic Flow and Dissipation in Heavy-Ion Collisions at E_{lab} = (1--160)A GeV

Elliptic flow in heavy-ion collisions at incident energies $E_{lab}\simeq$ (1--160)A GeV is analyzed within the model of 3-fluid dynamics (3FD). We show that a simple correction factor, taking into account dissipative affects, allows us to adjust the 3FD results to experimental data. This single-parameter fit results in a good reproduction of the elliptic flow as a function of the incident energy, centrality of the collision and rapidity. The experimental scaling of pion eccentricity-scaled elliptic flow versus charged-hadron-multiplicity density per unit transverse area turns out to be also reasonably described. Proceeding from values of the Knudsen number, deduced from this fit, we estimate the upper limit the shear viscosity-to-entropy ratio as $\eta/s \sim 1-2$ at the SPS incident energies. This value is of the order of minimal $\eta/s$ observed in water and liquid nitrogen.Comment: 10 pages, 7 figures, version accepted by Phys. Rev.

Shell model in the complex energy plane and two-particle resonances

An implementation of the shell-model to the complex energy plane is presented. The representation used in the method consists of bound single-particle states, Gamow resonances and scattering waves on the complex energy plane. Two-particle resonances are evaluated and their structure in terms of the single-particle degreees of freedom are analysed. It is found that two-particle resonances are mainly built upon bound states and Gamow resonances, but the contribution of the scattering states is also important.Comment: 20 pages, 9 figures, submitted to Phys.Rev.

Анализ доступности железнодорожного транспорта для населения крупных агломераций

The study is focused on improvement of passenger transportation by rail transport, its availability, quality of related services for residents of large agglomerations. Correlation of growth in speed of movement of passengers, distance of travel, range and quality of services provided by the carrier, as well as planning of passenger traffic and spatial urban development models are considered. Particular attention is paid to the analysis of the improvement of passenger transportation by rail transport by assigning stops for long-distance passenger trains (including fast, speed and highspeed trains) in suburban areas of large agglomerations, since that aspect has not been yet sufficiently studied.It is concluded that it is necessary to continue research on transportation needs of the population of the agglomerations, to identify the features and patterns of changes in passenger traffic, emerging and redeeming in the suburban areas of the largest cities. This will allow transportation companies to better understand the transport services market, to develop and offer new transportation products to the population. That approach can increase the attractiveness of rail transport and its availability for the population of many cities thanks to a significant reduction in weighted average costs and travel time expenditures for passengers.В центре исследования находится совершенствование пассажирских перевозок железнодорожным транспортом, их доступности, качества связанных с ними услуг для жителей крупных агломераций. Рассматриваются вопросы соотношения роста скорости перемещения пассажиров, дальности поездки, спектра и качества предоставляемых перевозчиком услуг, равно как планирования пассажирских перевозок   и схем пространственного развития городов. Особое внимание уделено малоизученному до сих пор аспекту – совершенствованию технологии пассажирских перевозок железнодорожным транспортом за счёт назначения остановок пассажирских поездов дальнего следования (в том числе скорых, скоростных и высокоскоростных) в пригородных зонах крупных агломераций. Делается вывод о необходимости продолжения исследований в отношении транспортных потребностей населения агломераций, выявления особенностей и закономерностей изменения пассажиропотоков, зарождающихся и погашающихся в пригородных зонах. Это может повысить привлекательность железнодорожного транспорта и его доступность для населения многих городов за счёт ощутимого для пассажира сокращения средневзвешенных стоимостных и временных транспортных затрат

Continuum effects for the mean-field and pairing properties of weakly bound nuclei

Continuum effects in the weakly bound nuclei close to the drip-line are investigated using the analytically soluble Poschl-Teller-Ginocchio potential. Pairing correlations are studied within the Hartree-Fock-Bogoliubov method. We show that both resonant and non-resonant continuum phase space is active in creating the pairing field. The influence of positive-energy phase space is quantified in terms of localizations of states within the nuclear volume.Comment: 27 RevTeX pages, 12 EPS figures included, submitted to Physical Review

Photon emission from bare quark stars

We investigate the photon emission from the electrosphere of a quark star. It is shown that at temperatures T\sim 0.1-1 MeV the dominating mechanism is the bremsstrahlung due to bending of electron trajectories in the mean Coulomb field of the electrosphere. The radiated energy for this mechanism is much larger than that for the Bethe-Heitler bremsstrahlung. The energy flux from the mean field bremsstrahlung exceeds the one from the tunnel e^{+}e^{-} pair creation as well. We demonstrate that the LPM suppression of the photon emission is negligible.Comment: 35 pages, 5 figure

Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials

The cross section for bremsstrahlung from highly relativistic particles is suppressed due to interference caused by multiple scattering in dense media, and due to photon interactions with the electrons in all materials. We present here a detailed study of bremsstrahlung production of 200 keV to 500 MeV photons from 8 and 25 GeV electrons traversing a variety of target materials. For most targets, we observe the expected suppressions to a good accuracy. We observe that finite thickness effects are important for thin targets.Comment: 52 pages, 13 figures (incorporated in the revtex LaTeX file

The theory of the Landau, Pomeranchuk, Migdal effect

Bremsstrahlung of photons from highly relativistic electrons is investigated. The cross section of the processes, which is suppressed due to a multiple scattering of an emitting electron in dense media (LPM effect) and due to photon interaction with electrons of a medium, is calculated with an accuracy up to "next to leading logarithm" and with the Coulomb corrections taken into account. Making allowances for a multiple scattering and a polarization of a medium an analysis of radiation on a target boundary is carried out. The method of consideration of radiation in a thin target under influence of the LPM effect is developed. Interrelation with the recent experiment is discussed.Comment: 36 pages, LaTeX, 3 eps figure