Jet analysis in lepton-hadron scattering from QCD

For deep inelastic lepton-hadron scattering we deduce from QCD perturbation theory the cross sections $\text{d}\text{σ}\text{d}\text{T}$ and $\text{d}\text{σ}\text{d}\text{S}$ in terms of the collective jet variables thrust T and spherocity S. We find that the shape of these cross sections depends mainly on the total hadronic energy W. While present data are consistent with the cross sections calculated they do not yet prove or disprove the presence of three-jet contributions. We predict that these contributions will be clearly visible for W ? 12 to 15 GeV.     

Event shapes in deep inelastic lepton-hadron scattering

The structure of hadronic final states in deep inelastic scattering expected from QCD is analyzed in terms of the shape parameters H_l and C_l. We find that the effects of the fragmentation of quarks and gluons into hadrons are typically governed by $\text{√s = [Q}{}^2\text{(1/x?1)]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. For √s?30 GeV, the distributions of events in H₂ and C₂ should allow a test of the perturbative QCD prediction of three-jet events.     

Strangeness in the proton as measured in elastic lepton-hadron scattering

In view of relevance of thevp-elastic scattering for the determination ofs-quark spin fraction, s in the proton, we reexamine the existing data. We use more refined parametrizations of both the vector and the axial vector form factors. The vector form factors are derived from the electromagnetic ones under assumptions on their strangeness content. Then we discuss the heavy quark contributions to the axial form factors and finally we perform a fit to thevp-elastic scattering data. previous conclusions about the fraction of the spin of the proton carried by thes-quark must be somewhat modified, especially if strangeness in the vector form factors is assumed.     

Multiplicities in highp t hadron-nucleus interactions

We present results obtained in π^? A (A=C, Cu, Pb) — collisions at 38 GeV/c. A single particle trigger selects events with one charged particle in the central region and large transverse momentum. The effect of this trigger on the multiplicities of all charged particles and of protons is shown.     

Polarized lepton-hadron scattering in asymptotically free gauge theories

We analyze polarized deep inelastic electron and neutrino scattering in asymptotically free gauge theories of the strong interactions. We compute the logarithmic deviations from Bjorken scaling in the moment sum rules for the structure functions due to the leading twist-2 and -3 operators that control the light-cone expansion. We also consider continuations to the elastic limit and to the Regge region.     

Tests for the charm changing charged current in lepton-hadron scattering

Starting from a weak charged hadronic current whose ΔC = 1 part is a general mixture of vector and axial vector currents, we work out experimental distributions of interest in inclusive and semi-inclusive lepton-hadron processes. Detailed consequences for the Cabibbo, Glashow-Iliopoulos-Maiani and De Rujula-Georgi-Glashow currents are presented. Special importance of the measurement of hadron multiplicities in the low-x region as a tool to probe the chiral structure of the charm changing current is pointed out.     

Measuring transversity densities in singly polarized hadron-hadron and lepton-hadron collisions

We show how the transverse polarization of a quark initiating a jet can be probed by the azimuthal distribution of two hadrons (of large z) in the jet. This permits a twist-2 asymmetry in hard processes when only one of the initial particles is polarized transversely. Applications to hadron-hadron and lepton-hadron scattering are discussed.     

Deep inelastic lepton-hadron scattering in massive vector gauge models

A class of strong interaction models in which the interactions between fractionally charged colored quarks are mediated by massive neutral vector gluons is considered. All the vector gluons acquire masses via the usual Higgs mechanism. The effective coupling constants $\text{g}$ (gauge coupling) and $\text{h}$ (quartic self-coupling) are supposed to approach a limit cycle in the limit of large space-like momenta. The large Q² behavior of the moments of the deep inelastic lepton-hadron structure functions is analysed using this hypothesis. It is shown that Bjorken scaling is violated by power terms of Q² multiplied by an oscillating function of Q².     

On the ω dependence of exclusive hadronic final states in lepton-hadron scattering

A framework is presented for studying the ω dependence of exclusive hadronic final states in lepton-hadron scattering (ω being Bjorken's scaling variable 2Mv/Q²). This is used for the analysis of K∫, KΛ, πN and πΔ final states.     

Rigorous results concerning light cone dominance in deep inelastic lepton-hadron scattering

We consider a class of distributions, appearing in electro-production and satisfying a Jost-Lehmann-Dyson representation. We then prove without further assumptions that only their singularity structure near the light cone is relevant for the behaviour of their Fourier transform in the Bjorken limit. Furthermore we study the ambiguity in this singularity structure introduced by the fact, that scaling is known only in the space like region of momentum space.Work supported by the Bundesministerium für Forschung und Technologie.     

Multiplicities of charged particles prior to fission

Electric monopole transitions between the 0 ₂ ⁺ , 0 ₁ ⁺ and 2 ₂ ⁺ , 2 ₁ ⁺ levels in⁷⁶Se, populated in the decay of⁷⁶Br, were investigated by means of conversion electrons and gammaray spectroscopy. TheK-electron intensity ratios ofE0 andE2 transitions connecting the 0 ₂ ⁺ level to the 0 ₁ ⁺ and 2 ₁ ⁺ levels and of theE0 andE2 components in the 2 ₂ ⁺ →2 ₁ ⁺ transition were determined. The ratioX(E0/E2) of theE0 toE2 reduced transition probabilities and, from the available lifetimes, theE0 strength parameters ρ(E0) were deduced for the two transitions. The results are compared with the predictions of current models.     

An intuitive approach to a generalized parton picture for high-energy lepton-hadron scattering

A generalized parton picture is developed, based on the impulse approximation. A parton is allowed to have non-point-like elastic form factors; inelastic current-parton scattering is taken into account explicitly. The amplitude of any exclusive channel of lepton-induced reactions is written down, with the parts containing the long-distance and the short-distance behavior of interaction dynamics clearly separated. Scaling violation is a natural feature of this picture. The inelastic structure functions, W₁ and νW₂, are studied in this scheme using various different theories; perturbative QCD, the scale-invariant parton model, the hadron bootstrap picture, and a phenomenological stripped-down hadron-parton model. The application of this picture to elastic lepton-hadron scattering and the problem of the selection of an infinite momentum frame are also discussed.     

Multiplicities and continuum γ-rays following heavy-ion reactions

The continuous γ-ray spectrum following (HI, xn) reactions is analyzed in terms of the competition between collective (rotational) and non-collective (statistical) modes of de-excitation at high spin. The dependence of the γ-ray intensity and of the multiplicity upon the parameters that define the rotational and the statistical modes is studied in an application of the model to the reaction ¹⁷⁶Yb(¹²C, 8n)¹⁸⁰Os at 120 MeV. It is found that that competition may be relevant throughout a rather large energy interval.     

Positivity inequalities for spin-dependent lepton-hadron scattering from the light-cone algebra of quark currents

Positivity inequalities restricting spin-dependent electron-nucleon scattering and neutrino-nucleon scattering have been found. Interesting bounds for the difference of the spin asymmetry on proton and neutron have been found from inequalities derived from the light-cone algebra of quark currents. The same results have been derived from the quark-parton model.     

The moment sum rules in the inclusive single soft pion observed lepton-hadron scattering

The moment sum rules are derived in inclusive lepton-hadron scattering where the single soft pion is observed. Further, it is suggested that charge asymmetry in these sum rules may give good evidence of the assumption to identify the soft pion at high energy as the directly produced pion in the central region.     

Trimuon final states in lepton-hadron scattering: Model-independent study of the production mechanism

It is pointed out the trimuon events due to conventional pair creation can be distinguished from heavy lepton and heavy quark production by model-independent spinparity selection rules. Asymmetries and (angular) moment integrals are defined which give a quantitative measure of the contributions due to the “new” sources. The same analysis can be applied to muon-pair production in hadronic collisions to determine the size of charm-particle (and other new flavor) production there.     

π0 Multiplicities in π+;p interactions at 10.5 GeVc

Measurement of the π⁰ multiplicity cross sections are reported for n₀ ? 6, where n⁰ is the number of produced π⁰ particles, and for N ? 8, where N is the number of charged particles. The inclusive π⁰ cross section is 29 ± 3 mb. Values for the correlation parameters, 〈n₀〉 and 〈n₀(n₀ ? 1)〉², are also presented.     

Fast 13C-NMR Spectral Editing for Determining CHn Multiplicities

With an improved version of the ¹³C DEPTQ NMR experiment all carbon multiplicities (C_q, CH, CH₂ und CH₃) can be identified unequivocally and most conveniently in two experiments and at best with only one scan each. This simplifies the analysis of ¹³C-NMR data on a routine level in general. With higher sample amounts and/or exploiting the high sensitivity of cryogenically cooled ¹³C probeheads the efficiency of such investigations may be improved. This makes this method attractive for fast ¹³C analysis of small-to-medium sized molecules in high-throughput laboratories.