Stringy corrections to Kaluza-Klein black holes

We consider string theory corrections to 4D black holes which solve the 5D vacuum Einstein equations. We find that the corrections vanish only for the extremal electric solution. We also show that for the non-extremal electric black hole the mass corrections are related to the charge corrections. The implications to string states counting and the correspondence principle for black holes and strings are discussed.     

Finite size effects for the dilute coupling Derrida model

There is a certain correspondence between the problems of information theory and spin-glass physics. The Derrida model occupies an important place here, as it is optimal in a certain sense. We have considered finite size corrections in the paramagnetic, spin-glass and ferromagnetic phases. At T = 0 the finite size corrections in the ferromagnetic phase have an important information theoretic meaning. We found singular corrections in the paramagnetic region and finite size corrections in the spin-glass region, which are responsible for the zero-modes. The connection between information theory and spin-glass physics and the physical meaning of finite size corrections are discussed in detail.     

Strahlungskorrekturen zure- p-Streuung für Winkel- und Energiekoinzidenz-Experimente

Calculations of radiative corrections to e-p-scattering are performed for experiments in which the final particles are detected in coincidence. Both the angles and energies of the outgoing particles are measured. The dependence of radiative corrections on angle and energy resolution parameters is discussed in detail.     

Radiative corrections to Higgs boson masses in supersymmetric models

The effect of radiative corrections on the Higgs masses and couplings in supersymmetric models is summarized. Radiative corrections in both the minimal and nonminimal models are discussed. It is pointed out that large singlet Higgs vacuum expectation values are screened out from the radiative corrections to the lightest Higgs mass in nonminimal models. In supersymmetric models the crucial mass limit for the Higgs search may be around 150 GeV.     

Radiative corrections to Higgs boson masses in supersymmetric models

The effect of radiative corrections on the Higgs masses and couplings in supersymmetric models is summarized. Radiative corrections in both the minimal and nonminimal models are discussed. It is pointed out that large singlet Higgs vacuum expectation values are screened out from the radiative corrections to the lightest Higgs mass in nonminimal models. In supersymmetric models the crucial mass limit for the Higgs search may be around 150 GeV.     

Spurious nature of certain unitarity corrections to the isobar model for three hadron final states

Various methods of implementing unitarity corrections to the isobar model for three hadron final states are discussed, and it is explained why some lead to spurious effects because insufficient attention is paid to analyticity. Recent calculations of unitarity corrections in the processes A1 → πππ and πN → ππN are shown to contain spuriously large effects. This may explain why fits to the first process were worsened when these corrections were included.     

Shadowing effects in nuclear parton distributions for small values ofx

The shadowing corrections to gluon and quark distributions in nuclei in the region of small values ofx are discussed. They are related to parton distributions in a pomeron which are in principle measurable in hard diffractive processes on the nucleon target. Multiple scattering corrections to shadowing are considered in a model dependent way. The perturbative QCD evolution of shadowing is also taken into account. Various possibilities of the partonic content of a pomeron are considered. It is shown in particular that the conventional parametrizations of parton distributions in a pomeron which are based on the assumption that it consists mostly of gluons imply substantial nuclear shadowing in gluon distributions in heavy nuclei. Possible phenomenological implications of shadowing corrections in nuclear parton distributions for various semi-hard processes with nuclear targets are briefly discussed.     

Elastic and inelastic scattering of high-energy particles on the deuteron

The scattering amplitudes on the deuteron at small momentum transfers are described, taking into account the shadow corrections. In the framework of Regge pole theory, the inelastic shadow corrections are expressed in terms of the amplitudes of inelastic processes. The validity limit of the formulae thus obtained is discussed.     

One-loop corrections to the Drell–Yan process in SANC

Radiative corrections to the neutral current Drell–Yan-like processes are considered. Complete one-loop electroweak corrections are calculated within the SANC system. Theoretical uncertainties are discussed. Numerical results are presented for typical conditions of LHC experiments. PACS 13.85.Qk; 12.15.Lk     

Nearly integrable systems

Intergable Hamiltonian systems with certain classes of perturbations such as higher order corrections are discussed. It is shown especially that integrable systems with first order corrections in the dispersive nonlinear wave equations can be transformed into higher order integrable systems at the same order approximation.     

One-loop corrections to the Drell–Yan process in SANC: the charged current case

Radiative corrections to the charged current Drell–Yan processes are revisited. Complete one-loop electroweak corrections are calculated within the automatic SANC system. Electroweak scheme dependence and the choice of the factorization scale are discussed. Comparisons with earlier calculations are presented. PACS 13.85.Qk, 12.15.Lk     

Exchange corrections to the density-density correlation function at a surface

The problem of calculating the density-density correlation function and of including the effects of exchange and correlation are discussed. It is shown in a model calculation how a particularly simple surface model can be easily extended to include exchange corrections. The effects of these corrections on the surface plasmon dispersion are found to be small.     

Sound transmission characteristics of Tee-junctions and the associated length corrections

The sound transmission characteristics of a Tee-junction formed by a sidebranch and an infinitely long duct are investigated numerically using the finite element method. The associated corrections of the branch length and the upstream duct length are also discussed in detail. The types of branch resonance that result in strong or weak sound transmission across the junction are determined and their effects on the length corrections examined. Results suggest that the type of sidebranch, the branch width, the branch length, and the order and the form of the resonance affect more significantly the length corrections of the duct section. The excitation of nonplanar higher branch modes gives rise to rapid increase in the duct length corrections and also results in lower sound transmission.     

Production of light fermion–antifermion pairs in \gamma\gamma collisions

The corrections to in the standard model are calculated for arbitrary light fermions f. The relevant analytical results are listed in a form that is appropriate for practical applications, and numerical results for integrated cross sections are discussed. The corresponding QED corrections are generally of the order of some per mille for arbitrary energies. The weak corrections to are negligible below the electroweak scale, reach the percent level at a few hundred GeV, and grow to about at 2 TeV. The weak corrections to and production have a shape similar to the one for , but they are larger by factors of about 1.4 and 3, respectively. Received: 18 December 1998 / Revised version: 1 March 1999 / Published online: 18 June 1999     

Connection between perturbation theory and lattice QCD

The problems associated with comparing perturbation theory and lattice Monte Carlo techniques when applied to QCD matter at zero net baryon number are discussed. In particular, the importance of next-to-leading order corrections to optimising the magnitude of the leading corrections to the equation of state and screening lenghts is emphasised.     

Dressed ion acoustic solitary waves in quantum plasmas with two polarity ions and relativistic electron beams

A theory for dressed quantum ion acoustic waves (QIAWs), which includes higher-order corrections when QIAWs are investigated by the reductive perturbation method, is presented for unmagnetized plasmas containing positive and negative ions and weakly relativistic electron beams. The properties of the QIAWs are investigated using a quantum hydrodynamic model, from which a Korteweg–de Vries equation is derived using the reductive perturbation method. An equation including higher-order dispersion and nonlinearity corrections is also derived, and the physical parameter space is discussed for the importance of these corrections.     

QCD radiative corrections to charged current heavy quark production

The QCD radiative corrections to charged current heavy quark production are given in the limit that the weak partner is massless, i.e. using a bottom structure function for top quark production. The results for charm production in neutrino nucleon scattering agree with those published before, but our method enables us to study all outgoing particles. The corrections to top production at the proposed LEP/LHC electroproton collider are discussed.     

Radiative corrections to photoeffect and the high-frequency end of the Bremsstrahlung spectrum

Radiative corrections to K-shell atomic photoeffect assuming a point Coulomb atomic potential and sufficiently high photoelectron velocities (αZ/β ? 1) are evaluated to lowest order in αZ. The result describes also the radiative corrections to the high-frequency end of the bremsstrahlung spectrum. The low- and high-energy limits are presented and discussed.