Resummation of double logarithms in electroweak high energy processes

At future linear $e^+e^-$ collider experiments in the TeV range, Sudakov double logarithms originating from massive boson exchange can lead to significant corrections to the cross sections of the observable processes. These effects are important for the high precision objectives of the Next Linear Collider. We use the infrared evolution equation, based on a gauge invariant dispersive method, to obtain double logarithmic asymptotics of scattering amplitudes and discuss how it can be applied, in the case of broken gauge symmetry, to the Standard Model of electroweak processes. We discuss the double logarithmic effects to both non-radiative processes and to processes accompanied by soft gauge boson emission. In all cases the Sudakov double logarithms are found to exponentiate. We also discuss double logarithmic effects of a non-Sudakov type which appear in Regge-like processes.Comment: 26 pages, 3 figures, Latex2

Baryon wave function in large-Nc QCD: Universality, nonlinear evolution equation and asymptotic limit

The 1/Nc expansion is formulated for the baryon wave function in terms of a specially constructed generating functional. The leading order of this 1/Nc expansion is universal for all low-lying baryons [including the O(1/Nc) and O(Nc^0) excited resonances] and for baryon-meson scattering states. A nonlinear evolution equation of Hamilton-Jacobi type is derived for the generating functional describing the baryon distribution amplitude in the large-Nc limit. In the asymptotic regime this nonlinear equation is solved analytically. The anomalous dimensions of the leading-twist baryon operators diagonalizing the evolution are computed analytically up to the next-to-leading order of the 1/Nc expansion.Comment: 44 page

Photon-Reggeon Interaction Vertices in the Nla

We calculate the effective vertices for the quark-antiquark and the quark-antiquark-gluon production in the virtual photon - Reggeized gluon interaction. The last vertex is considered at the Born level; for the first one the one-loop corrections are obtained. These vertices have a number of applications; in particular, they are necessary for calculation of the virtual photon impact factor in the next-to-leading logarithmic approximation.Comment: 20 pages, references adde

Exclusive diffractive production of real photons and vector mesons in a factorized Regge-pole model with non-linear Pomeron trajectory

Exclusive diffractive production of real photons and vector mesons in ep collisions has been studied at HERA in a wide kinematic range. Here we present and discuss a Regge-type model of real photon production (Deeply Virtual Compton Scattering), as well as production of vector mesons (VMP) treated on the same footing by using an extension of a factorized Regge-pole model proposed earlier. The model has been fitted to the HERA data. Despite the very small number of the free parameters, the model gives a satisfactory description of the experimental data, both for the total cross section as a function of the photon virtuality Q2 or the energy W in the center of mass of the gamma\star-p system, and the differential cross sections as a function of the squared four-momentum transfer t with fixed Q2 and W.Comment: 34 pages, 82 figures accepted by Physical Review

Dysmetabolic mechanisms of preeclampsia development

Background: An in-depth study of dismetabolic mechanisms in the genesis of pre-eclampsia (PE) has been updated because pregnancy is considered as a natural model of metabolic syndrome (MS), as well as the metabolic disorders are important in development of essential hypertension.Aims: to reveal clinical and laboratory parallels in pregnancy complicated by PE without MS and pregnancy proceeding on the background of MS to assess the role of metabolic disturbances in the development of PE.Materials and methods: 82 women with MS were examined in the dynamics of pregnancy and were divided into 2 groups depending on the implementation of PE: group I consisted of 50 women with PE on the background of MS, group II 32 women with MS without PE. We formed group III consisting of 44 pregnant women with PE without accompanying diseases to assess the pathogenetic value of metabolic disorders in the development of PE. The IV (control) group consisted of 30 healthy women with physiological pregnancy. Metabolic, hematological parameters, hormones, markers of the proinflammatory state, endothelial hemostasiological dysfunction, decidualization and placental angiogenesis, accumulation dynamics and distribution loci of adipose tissue were determined in all pregnant women.Results: In the groups of pregnant women with PE, changes similar to MS were revealed: pronounced diabetic and atherogenic disorders with the development of pathological insulin resistance, hyperinsulinemia and leptinemia, endothelial-platelet link hyperactivation, thrombotic and inflammatory status, visceral type of fat deposition, hyperuricemia, hypersympathicotonia. It is proved that in the hierarchy of mechanisms of PE formation, placental dysfunction is a secondary alteration factor, which additionally potentiates the insulin resistance increase and the effects of structural and functional destabilization of the vascular endothelium.Conclusions: The direction of metabolic changes during pregnancy, the common development of PE and MS indicate the important role of dismetabolic mechanisms in the formation of PE

Infrared safety of impact factors for colourless particle interactions

We demonstrate, to next-to-leading order accuracy, the cancellation of the infrared singularities in the impact factors which arise in the QCD description of high energy processes A + B -> A' + B' of colourless particles. We study the example where A is a virtual photon in detail, but show that the result is true in general.Comment: 31 pages latex including 10 figure

Production of a gluon with the exchange of three reggeized gluons in the Lipatov effective action approach

In the Regge kinematics the amplitude for gluon production off three scattering centers is found in the Lipatov effective action technique. The vertex for gluon emission with the reggeon splitting in three reggeons is calculated and its transversality is demonstrated. It is shown that in the sum of all contributions terms containing principal value singularities are cancelled and substituted by the standard Feynman poles. These results may be used for calculation of the inclusive cross-section for gluon production on two nucleons in the nucleus.Comment: 22 pages, 9 figures; submitted to Eur.Phys.Jour.

The BFKL Pomeron in 2+1 Dimensional QCD

We investigate the high-energy scattering in the spontaneously broken Yang - Mills gauge theory in 2+1 space--time dimensions and present the exact solution of the leading $\ln s$ BFKL equation. The solution is constructed in terms of special functions using the earlier results of two of us (L.N.L. and L.S.). The analytic properties of the $t$-channel partial wave as functions of the angular momentum and momentum transfer have been studied. We find in the angular momentum plane: (i) a Regge pole whose trajectory has an intercept larger than 1 and (ii) a fixed cut with the rightmost singularity located at $j=1$. The massive Yang - Mills theory can be considered as a theoretical model for the (non-perturbative) Pomeron. We study the main structure and property of the solution including the Pomeron trajectory at momentum transfer different from zero. The relation to the results of M. Li and C-I. Tan for the massless case is discussed.Comment: 28 pages LATEX, 3 EPS figures include