Flux confinement in the leading logarithm model

We study the statics of quasi-abelian quark and antiquark source charges in the approximation in which leading logarithm radiative corrections are retained in the gauge gluon effective action functional. We show that the partial differential equation for the flux function is of degenerating elliptic type, leading to flux confinement within a free boundary which is a characteristic. The static potential increases linearly for large source separations, with a logarithmic subdominant term.     

Chiral symmetry restoration in hadron spectra

The evidence and the theoretical justification of chiral symmetry restoration in high-lying hadrons is presented.     

Hump-backed QCD plateau in hadron spectra

New data on inclusive energy distribution of hadrons from quark jets ine ⁺ e ^? annihilation are shown to agree with the quantitative predictions of perturbative QCD, supporting the hypothesis of local parton-hadron duality.     

The modified Glauber approximation

This article reviews the modified Glauber approximation which has been considered for electron and positron-atom scatterings at intermediate energies during the last decade. The theoretical basis for the proposal of the method is expounded and the results of the calculation in various atomic collision processes are presented. Some alternative methods of approximation which may be used in an attempt to improve the modified Glauber approximation at this range of energies are also discussed.     

The Sudakov form factor beyond the leading logarithmic approximation

We present the general form of the asymptotic behavior of the massless electron-photon vetex function in quantum electrodynamics in the limit whereq ², the virtual mass of the photon, becomes large. All the logarithms inq ² are taken into account, whereas inverse powers ofq ² are neglected. In contradistinction to previous investigations we consider the off-shell vertex function and work in the Feynman gauge. Extensive use is made of the α-representation of Feynman integrals.     

Quenching of hadron spectra in DIS on nuclear targets

The multiple scatterings incurred by a hard quark produced in a nuclear medium induce the emission of soft gluons which carry a fraction of the quark energy and eventually affect the hadronization process. Here, the depletion of semi-inclusive hadron spectra in DIS on various nuclei (N, Ne, Cu, Kr) is computed as a function of and z to leading order in through medium-modified fragmentation functions. Using the transport coefficient previously determined from Drell-Yan production, the predictions are found to be in good agreement with EMC and HERMES preliminary data. Calculations on Xe targets are also presented and discussed.Received: 24 June 2003, Published online: 20 August 2003     

Mass generation in coalescence — Effects on hadron spectra

Different scenarios for the creation of constituent mass in the hadron formation process are discussed. Effects of these may be observable in hadron momentum spectra.     

Re-hardening of hadron transverse mass spectra in relativistic heavy-ion collisions

We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma formation     

Largep T double photon production in hadronic collisions-beyond leading logarithm QCD calculation

We calculateO(α _s ) corrections to largep _T double photon production in hadronic collisions. We find that these corrections to the basic \(q\bar q \to \gamma \gamma \) subprocess are important, preventing to describe double photon production on the basis of the leading logarithm approximation only. We give a phenomenological discussion of the results obtained at SPS, ISR and \(Sp\bar pS\) energies. In particular, we investigate how the effect of the intrinsic parton <K _T> may be disentangled from the perturbative contribution. We also calculate the aplanarity distribution characteristic of 3 jet events.     

The evolution of short distance phase space quanta into hadron jets

A statistical model fore ⁺ e ^? annihilation into hadrons is presented which explains at the same time some short distance phenomena (multiple jet structure, rate of three jet events, scaling) and large distance phenomena (hadron final states, multiplicities). We investigate the change of phase space structure with time under the assumption that the interaction volume expands with velocity of light. At short distancesL?m _π ^?1 elementary quanta in the instantaneous phase space with mass spreadΔm～L ^?1 can be produced. They are unstable and evolve into the jets of hadrons. The time evolution of the system is uniquely determined by sequential application of our principle of equipartition in instantaneous phase space.     

Collinear radiative electron-positron scattering in the leading logarithmic approximation

Radiative corrections to the cross section of the radiative large-angle Bhabha scattering process at high energies are calculated. The kinematics in which a hard photon is emitted along one of the momentum directions of the charged fermions is considered. Contributions coming from the emission of virtual, soft, and hard additional photons are taken into account in the leading logarithmic approximation. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 12, 851–855 (25 June 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Analytic calculation of hadron spectra by random-walk approximations in lattice QCD

We explain the detail of how to calculate the meson and baryon spectrum by a random walk approximation analytically. The results are compared with experimental values and Monte Carlo results.     

CP-violating asymmetries in penguin-inducedB-meson decays beyond the leading logarithmic approximation

We investigate CP-violating phenomena both in semi-inclusive and exclusive penguin-inducedB-meson decays by using low energy effective Hamiltonians for |ΔB|=1, ΔC=ΔU=0 transitions including leading and next-to-leading order OCD corrections. In particular, we discuss the renormalization scheme dependences arising beyond the leading order and their explicit cancellation for the physical transition amplitudes. In order to estimate the hadronic matrix elements needed for the exclusive penguin modes, we apply both the Bauer, Stech, Wirbel model and the meson model of Brodsky and Lepage. Numerical results are presented for semi-inclusive \(b \to q'\bar qq(q',q \in \{ d,s\} )\) modes and the exclusive decaysB ^?→K ^? K ⁰, \(B^ - \to \pi ^ - \bar K^0 \) , and \(B_d^0 \to K^0 \bar K^0 \) .