Forward hadron-hadron scattering at high energy

The high energy elastic scattering of pp, , pπ⁺, pπ⁻, pk⁺ andpk ⁻ processes is studied at forward directions. The expressions for total scattering cross-sections and the ratios of real-to-imaginary parts of the forward amplitude are derived inP+f model. For the Regge part of the scattering amplitude, the standard form is taken. For the pomeron part, the Harari-Freund conjecture is assumed. The background is assumed to get dominant contributions from the multiparticle exchanges in that channel. These contributions are obtained by parametrising the branch cuts by conformal mapping and polynomial expansion methods. The agreement with the experiment is good. The fits suggest strong exchange degeneracy forpp andkp which in turn is consistent with the Harari-Freund duality.     

Spin effects in high energy hadron-hadron scattering

The spin-flip amplitudes of the meson-nucleon and nucleon-nucleon scattering are calculated in the framework of the dynamic model taking into account the interactions at large distances. The consideration of the strong form factors at the corresponding vertex and prea-symptotic contributions allowed us to describe correctly the differential cross sections and spin effects of hadron-hadron scattering at high energies. On this basis predictions at high and superhigh energies are made.     

Evolution equations at large-x and higher twist effects

Approximate solutions of Altarelli-Parisi (AP) equataions for flavour non-singlet and singlet structure functions at large-x are presented. A bound on higher twist (HT) effect incorporating infinite number of non-leading terms is obtained. Comparision is then made with recent SLAC, BCDMS, and EMC data at large-x.     

Evolution equations at large-x and higher twist effects

Approximate solutions of Altarelli-Parisi (AP) equataions for flavour non-singlet and singlet structure functions at large-x are presented. A bound on higher twist (HT) effect incorporating infinite number of non-leading terms is obtained. Comparision is then made with recent SLAC, BCDMS, and EMC data at large-x.     

Large corrections to high-pT hadron-hadron scattering in QCD

We have computed the first non-trivial QCD corrections to the quark-quark scattering process which contributes to the production of hadrons at large p_T in hadron-hadron collisions. Using quark distribution functions defined in deep inelastic scattering and fragmentation functions defined in one particle inclusive e⁺e^? annihilation, we find that the corrections are large. This implies that QCD perturbation theory may not be reliable for large-p_T haron physics.     

About the vacuum structure in QCD and hadron-hadron scattering

We comment on an unconventional factorization scheme which has been recently proposed by Nachtmann and Reiter. These authors propose to take into account the influence of the vacuum structure of QCD by including a correlation in spin and colour for the partons that initiate a hard scattering process. We show on a specific example that such a factorization is either trivial in colour or spoiled by leading twist infrared divergences.     

The vacuum structure in QCD and hadron-hadron scattering

Standard ideas on the structure of the vacuum in QCD suggest it to be full of fluctuating color fields. We investigate the possible influence of the chromomagnetic vacuum fields on high energy hadron-hadron reactions. We suggest that high energy quarks traversing these fields will produce soft gluon and photon radiation analogous to synchrotron radiation from electrons and positrons in a storage ring. We argue that this radiation will lead to polarization phenomena for quarks in spin- and colorspace which in turn can explain theK-factor in the Drell-Yan reaction. We point out that jet production offers another way to study these polarization phenomena. We present then a calculation of the number of “synchrotron” photons which should be emitted inp?p collisions at high energies. Thus, we predict a sizable signal of prompt photons of nnergy less than a few hundred MeV with a characteristic frequency distribution. Observation of such photons would give strong support to our naive picture. Finally we point out a number of other phenomena like charmed particle decays where our “synchrotron” effect may be of importance.     

Factorization in relativistic heavy-ion scattering

We have calculated the total cross sections for relativistic nucleus-nucleus scattering in the Glauber theory and conclude that there will be no factorization, due to the short-range nature of nucleon-nucleon interaction as compared to the sizes of the colliding nuclei.     

A higher twist in string theory

Considering the gauge field and its dual in heterotic string theory as a unified field, we show that the equations of motion at the rational level contain a twisted differential with a novel degree seven twist. This generalizes the usual degree three twist that lifts to twisted K-theory and raises the natural question of whether at the integral level the abelianized gauge fields belong to a generalized cohomology theory. Some remarks on possible such extension are given.     

Quark gluon scattering at higher orders in QCD

The infrared evolution equation which sums up leading logarithmic terms is solved for the partonic reactionqgqX in the elastic case i.e.M _X0. The results of the exactO( _s ³ ) calculation are reproduced.