5,832 research outputs found

    One loop light-cone QCD, effective action for reggeized gluons and QCD RFT calculus

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    The effective action for reggeized gluons is based on the gluodynamic Yang-Mills Lagrangian with external current for longitudinal gluons added, see [1]. On the base of classical solutions, obtained in [2], the one-loop corrections to this effective action in light-cone gauge are calculated. The RFT calculus for reggeized gluons similarly to the RFT introduced in [3] is proposed and discussed. The correctness of the results is verified by calculation of the propagator of A+A_{+} and AA_{-} reggeized gluons fields and application of the obtained results is discussed as well.Comment: 24 page

    On the application of the effective action approach to amplitudes with reggeon splitting

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    Application of the effective action approach to amplitudes with loop integration is studied for collisions on two and three centers with possible gluon emission. A rule is formulated for the integration around pole singularities in the induced vertices which brings the results in agreement with the QCD. It is demonstrated that the amplitudes can be restored from the purely transverse picture by introducing the standard Feynman propagators for intermediate gluons and quarks.Comment: 16 pages, 9 figures; submitted to Eur.Phys.Jour.

    Diffractive scattering on the deuteron projectile in the NLO: triple interaction of reggeized gluons

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    High-mass diffractive production of protons on the deuteron target is studied in the next-to-leading order (NLO) of the perturbative QCD in the BFKL approach. The non-trivial part of the NLO contributions coming from the triple interactions of the exchanged reggeons is considered. Analytic formulas are presented and shown to be infrared free and so ready for practical calculation.Comment: 28 pages, 2 figures; to be published in Eur.Phys.Jour.

    Inverse Compton scattering in mildly relativistic plasma

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    We investigated the effect of inverse Compton scattering in mildly relativistic static and moving plasmas with low optical depth using Monte Carlo simulations, and calculated the Sunyaev-Zel'dovich effect in the cosmic background radiation. Our semi-analytic method is based on a separation of photon diffusion in frequency and real space. We use Monte Carlo simulation to derive the intensity and frequency of the scattered photons for a monochromatic incoming radiation. The outgoing spectrum is determined by integrating over the spectrum of the incoming radiation using the intensity to determine the correct weight. This method makes it possible to study the emerging radiation as a function of frequency and direction. As a first application we have studied the effects of finite optical depth and gas infall on the Sunyaev-Zel'dovich effect (not possible with the extended Kompaneets equation) and discuss the parameter range in which the Boltzmann equation and its expansions can be used. For high temperature clusters (kBTe15k_B T_e \gtrsim 15 keV) relativistic corrections based on a fifth order expansion of the extended Kompaneets equation seriously underestimate the Sunyaev-Zel'dovich effect at high frequencies. The contribution from plasma infall is less important for reasonable velocities. We give a convenient analytical expression for the dependence of the cross-over frequency on temperature, optical depth, and gas infall speed. Optical depth effects are often more important than relativistic corrections, and should be taken into account for high-precision work, but are smaller than the typical kinematic effect from cluster radial velocities.Comment: LateX, 30 pages and 11 figures. Accepted for publication in the Astrophysical Journa

    Unifying approaches: BK equation from the Lipatov's effective action

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    We consider a direct derivation of the Balitsky-Kovchegov equation~\cite{Bal,Kovch} from the Lipatov's effective action~\cite{LipatovEff} formulated in terms of interacting ordered exponentials~\cite{OurZub}. We discuss the way the sub-leading eikonal corrections to the Balitsky-Kovchegov equation arise from the transverse field contribution and sub-leading eikonal corrections to the quark propagator. We outline other possible applications of the proposed calculation scheme.Comment: 22 page

    Wien Fireball Model of Relativistic Outflows in Active Galactic Nuclei

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    We study steady and spherically symmetric outflows of pure electron-positron pair plasma as a possible acceleration mechanism of relativistic jets up to the bulk Lorentz factor of greater than 10. These outflows are initiated by the ``Wien fireball'', which is optically thick to Compton scattering but thin to absorption and in a Wien equilibrium state between pairs and photons at a relativistic temperature.Comment: 16 pages, 13 figures, 1 table, ApJ in pres

    Evolution of the Low-Energy Photon Spectra in Gamma-Ray Bursts

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    We report evidence that the asymptotic low-energy power law slope alpha (below the spectral break) of BATSE gamma-ray burst photon spectra evolves with time rather than remaining constant. We find a high degree of positive correlation exists between the time-resolved spectral break energy E_pk and alpha. In samples of 18 "hard-to-soft" and 12 "tracking" pulses, evolution of alpha was found to correlate with that of the spectral break energy E_pk at the 99.7% and 98% confidence levels respectively. We also find that in the flux rise phase of "hard-to-soft" pulses, the mean value of alpha is often positive and in some bursts the maximum value of alpha is consistent with a value > +1. BATSE burst 3B 910927, for example, has a alpha_max equal to 1.6 +/- 0.3. These findings challenge GRB spectral models in which alpha must be negative of remain constant.Comment: 12 pages (including 6 figures), accepted to Ap

    Influence of scattering processes on electron quantum states in nanowires

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    In the framework of quantum perturbation theory the self-consistent method of calculation of electron scattering rates in nanowires with the one-dimensional electron gas in the quantum limit is worked out. The developed method allows both the collisional broadening and the quantum correlations between scattering events to be taken into account. It is an alternativeper seto the Fock approximation for the self-energy approach based on Green’s function formalism. However this approach is free of mathematical difficulties typical to the Fock approximation. Moreover, the developed method is simpler than the Fock approximation from the computational point of view. Using the approximation of stable one-particle quantum states it is proved that the electron scattering processes determine the dependence of electron energy versus its wave vector

    Effect of surface modification of 5KHV2S steel on the mechanism and intensity of contact wear

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    The paper presents the experimental study of the contact wear of 5KHV2S steel after surface modification. It is shown that without hardening of the surface layer, 5KHV2S steel is capable of satisfactory operation when a pulsating contact stress of 970 MPa is applied. The most qualitative type of surface modification is the hardening of the surface layer by nitrocementation carried out before quenching and tempering. The proposed technology of volumetric- surface hardening, including forging in a new forging tool, chemical-thermal treatment, quenching and lowtemperature tempering, provided the possibility of increasing the pulsating contact stress to 1 100 MPa, and the operation period during the first 13 000 loading cycles gives wear of the working surface no more than 0,1 mm
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