Phase space and multihadron production in annihilation processes at present energies

With the conjecture that the weak neutral current should have equal status in symmetry as the other weak and electromagnetic currents, we determine it to be a pure axial-vector. This means that the weak interaction of the neutral current is parity conserving. The fundamental interactions of leptons thereby complete the whole scheme of (1 + γ₅)/2, (1 ? γ₅)/2,1 and γ₅.     

Stochastic processes and multihadron production

Acta physica Academiae Scientiarum Hungaricae - Statistical multihadron production models are considered in a stochastic framework. The predictions of the stochastic quark model of hadron clusters...     

The pomeron-particle total cross section and diffractive production of showers at very high energies

The experimental data of ISR and NAL for the process pp → pX are used for the determination of the pomeron-particle total cross section and the triple-pomeron vertex. Estimates of the cross sections of the diffractive production of one and several showers of particles are given. It is shown that at s ～ 10³ GeV² the cross section of all inelastic diffractive processes is ～ 6 mb and grows with energy. A theoretical estimate of the amplitude of pomeron-pomeron scattering is given.     

Hard diffractive quarkonium hadroproduction at high energies

We present a study of heavy quarkonium production in hard diffractive processes by pomeron exchange for Tevatron and LHC energies. The numerical results are computed using a recent experimental determination of the diffractive parton density functions in the pomeron and these are corrected by unitarity corrections through the gap survival probability factor. We give predictions for single as well as central diffractive ratios. These processes are sensitive to the gluon content of the pomeron at small Bjorken variable x and may be particularly useful in studying small-xphysics. They may also be a good place to test the different available mechanisms for quarkonium production at hadron colliders. PACS 13.60.Hb; 12.38.Bx; 12.40.Nn; 13.85.Ni; 14.40.Gx     

Systematics of hadron-proton diffractive scattering at high energies

We apply the eikonal formalism to existingπ ^±,K ^±,p, \(\bar p\) ,∑ ^? andΞ ^? elastic scattering data on a target proton in order to perform a detailed test of the additivity of eikonals of the constituent quark-quark interaction. The difference between the pion and kaon channels imposes an obvious flavor dependence. In addition, the systematic treatment of meson and baryon scattering for all values oft requires a renormalization of the fundamental interaction strength which persists in a rescattering treatment of the problem as well as with the inclusion of gluonic degrees of freedom. A variety of form factors and elementary amplitudes are studied with wide ranging consequences on the quality of the reproduction of the data.     

Two-photon processes at very high energies

Formulae are presented by which a numerically stable computer program for two-photon processes above $\text{s}\text{= 100}\text{GeV}$ can be constructed. For this purpose a new method for evaluating matrix elements is introduced. It is then shown that two-photon processes should be no background to Drell-Yan signals in pp collisions. A comparison is made between two-photon physics at e⁺e^?, ep and pp collisions.     

Peripherical processes in QED at high energies

In this review we consider the high energy processes in QED frames in peripherical kinematics. The key feature of this kinematics is that processes have a large cross section which do not decrease with the increasing of the initial center of mass energy. Two purposes to study peripheral processes are: the background processes with large total cross sections and the structure of jets in the fragmentation region.We describe the various QED peripherical processes in terms of Impact Factors and give the explicit expressions for the differential distributions and spin correlation effects, as well as estimates of the total cross section of peripheral processes in photon-photon, photon-lepton and lepton-lepton collisions.A special attention is paid to the small-angle Bhabha scattering process which is relevant for beam monitoring at LEP I, LEP II.Based on analytical properties of the amplitudes some relations (QED sum rules) between the high energy asymptotic of the cross sections of inelastic processes in e ⁺ e ^? collisions and higher order perturbative contributions to the electron Dirac and Pauli form-factors are derived.For practical using we present some loop momentum integrals.     

On charm production at high energies

A number of new huge neutrino telescopes have been built, are being built, and are planned to be built all over the world. With these setups, cosmic neutrinos of high energies can be studied experimentally. Atmospheric neutrinos represent the main backgrounds to such experiments—namely, the atmospheric neutrinos determine how large a setup should be to measure diffuse cosmic neutrino fluxes or what angular resolution of a setup should be in order that searches for pointlike neutrino sources in the sky be successful. The atmospheric-neutrino fluxes are calculated in the present study. At high energies, the atmospheric-neutrino fluxes consist mostly of neutrinos produced in the atmosphere through charmed-particle decays. Three sources of information about charm production are used: (1) data obtained in accelerator experiments, (2) data on cosmicray muons, and (3) predictions of the NLO and QGSM QCD models for the charm-production at energies not available at modern accelerators. The uncertainties in the calculated fluxes of atmospheric neutrinos from charmed-particle decays are estimated to be at a level of 3–5 orders of magnitude.     

Some charge exchange processes at very high energies

A systematic study of the cross sections for the charge exchange scattering of the type N₁ + + (N₂ + e)(N₁ + e) + N₂ for various nuclei at high energies has been presented. A discussion of the results revealing interesting features has also been included.The authors are thankful to Professor P. K.Ghosh for his interest in this work. Computations reported in this article were done on the IBM 1130 system at the Computer Centre, Calcutta University.     

Multifractal statistics of multiparticle production at high energies

It is shown that high energy multiparticle production near the morphological phase transition from monofractality to multifractality is characterized by a multifractal Bernoulli distribution. Experimental data on hadron-hadron, hadron-nucleus and on heavy ions collisions are used to show an universal character of this distribution (and, consequently, of the morphological phase transition) in multiparticle production at high energies. Received: 23 July 1998 / Revised version: 25 November 1998     

A wave-packet formulation of multiparticle production at high energies

Starting from a free boson gas in a box, we formulate a statistical approach to multi-particle production. The specific feature of the small box quantization is the fact that one-particle wave functions are wave packets instead of plane waves. In this context we investigate the jet model with Bose-Einstein (BE) statistics. The transverse cut-off function is naturally related to the size of the box (production region). We compare our results with experimental data.     

Pomeron structure in processes of diffractive open-charm production

On the basis of the Capella-Kaidalov-Merino-Tran Thanh Van (CKMT) model, the parametrization of the gluon density in the Pomeron is determined from data of the ZEUS experiment devoted to studying diffractive D*-meson production. Experimental data on the open-charm contribution to the diffractive structure function are successfully reproduced within this conceptual framework.     

The diffractive component of particle production in the dual multistring fragmentation model

The single diffractive component is introduced in the dual Monte Carlo chain decay model of soft particle production. The diffractively excited multiparticle states in this model arise from the fragmentation of two chains formed out of the valence quarks and antiquarks (or diquarks) of the diffractively excited hadron and a sea quark-antiquark pair of the Pomeron, considered to be a gluonic object. In this way the excited clusters behave in a way quite similar to multiparticle states formed in nondiffractive meson-hadron collisions. The calculated multiparticle states agree quite well with recent data from the UA4-SPS collider collaboration and with recent data on strange particle production in diffractive photon-proton collisions.     

Phenomenology of light- and strange-quark simultaneous production at high energies

This letter presents an extension of EPL116(2017)62001 to light- and strange-quark nonequilibrium chemical phase-space occupancy factors (γ_q,s). The resulting damped trigonometric functionalities relating γ_q,s to the nucleon-nucleon center-of-mass energies (\(\sqrt {{s_{NN}}} \)) looks very similar except different coefficients. The phenomenology of the resulting γ_q,s(\(\sqrt {{s_{NN}}} \)) describes a rapid decrease at \(\sqrt {{s_{NN}}} \) ? 7GeV followed by a faster increase up to ~20 GeV. Then, both γ_q,s become nonsensitive to \(\sqrt {{s_{NN}}} \). Although these differ from γ _s (\(\sqrt {{s_{NN}}} \))obtained at γ _q (\(\sqrt {{s_{NN}}} \))=1, various particle ratios including K⁺/π⁺, K^?/π^?, Λ/π^?, Λ?/π^?, Ξ⁺/π⁺, and Ω/π^?, can well be reproduced, as well. We conclude that γ_q,s(\(\sqrt {{s_{NN}}} \)) should be instead determined from fits of various particle yields and ratios but not merely from fits to the particle ratio K⁺/π⁺.     

Phenomenology of single-spin effects in hadron production at high energies

Within a phenomenological model, experimental data on the transverse single-spin asymmetry (A _N ) and polarization (P _N ) of hadrons are analyzed for 68 different inclusive reactions in hadron-hadron, hadron-nucleus, nucleus-nucleus, and lepton-nucleon interactions. A mechanism that is based on the interaction of the chromomagnetic moment of massive constituent quarks with the effective nonuniform chromomagnetic field of QCD strings formed after the initial color exchange is considered as the origin of single-spin effects. Quark-spin precession in the chromomagnetic field is taken into account. Dynamical masses and anomalous chromomagnetic moments are estimated for constituent u, d, s, c, and b quarks.     

Single pion production by linearly polarized photons at high energies

There exists a one-to-one correspondence between the dependence of the single-pion-photoproduction amplitude on the linear polarization of the photons at high energies and small momentum transfer in the direct channelγ+N→π+N on one hand and the parity of the exchanged particle-system in the crossed channelγ+π→N+¯N on the other.