Quark mass effects in deeply inelastic scattering

We argue that the difference between the structure functions corresponding to deep inelastic scattering with and without heavy quarks in the current fragmentation region scales at high Q² and fixed (low) x _Bj.     

Multiple scattering, parton energy loss, and modified fragmentation functions in deeply inelastic eA scattering

Modified quark fragmentation functions in deeply inelastic eA collisions and their QCD evolution equations are derived for the first time in the framework of multiple parton scattering. Induced radiation gives rise to additional terms in the evolution equations and thus softens the modified quark fragmentation functions. The results in the next-leading-twist depend on both diagonal and off-diagonal twist-four parton distributions and the combination of which clearly manifests the LPM interference pattern. The predicted modification depends quadratically on the nuclear size ( A2/3). Generalization to the case of hot QCD medium is also discussed.     

Elastic and inelastic φ photoproduction

The differential cross section of the reaction (γp → pφ) has been measured in the t range 0 ? t ? 0.4 GeV² and for photon energies from 3.0 to 6.7 GeV. In particular for the small t region the measurement accuracy was better than 10%. We obtained for the slope parameter B in an exponential parametrization of the differential cross section dσ/dt = Ae^?Bt values of $\text{B ? 6 ± 0.5}\text{GeV}{}^{\mathrm{?2}}$ which are significantly larger than the slopes obtained by most other experiments at higher t values. This indicates a t dependence of B particularly in the small t region.An energy dependence of the optical point (dσ/dt)_t=0, observed in our measurements, has been explained as a kinematic effect due to the VDM relation. A fit of our measurements is in excellent agreement with all other published values of (dσ/dt)_t=0(γp → φp), this implies that σ_tot(φp) must be essentially energy independent in this energy range.Spin density matrix elements of the φ have been evaluated and an analysis of the helicity amplitudes has been carried out. This analysis confirmed s-channel helicity conservation. Moments of spherical harmonics of the $\text{K}\text{K}$ angular decay distribution have been computed for 10 MeV $\text{K}\text{K}$ mass-bins from threshold to 1.3 GeV. The mass dependence of the normalized moments is generally smooth. Contributing amplitudes have essentially only even moments. The moment 〈Y₂⁰〉/〈Y₀⁰〉 changes sign above the φ mass.Differential cross sections for the inelastic φ production γp → φX have been evaluated for the first time both with respect to t?t_min and M_K. The integrated inelastic cross sections are comparable in size with the elastic ones. The slopes of the differential cross sections dσ/dt appear to become flatter with increasing M_X.     

Multi-step processes in high-energy elastic and inelastic nuclear scattering

Multi-step processes in elastic and inelastic nuclear scattering at intermediate and high energies are investigated using a formulation whereby a finite number of channels are explicitly treated while all the other channels are approximately accounted for through a “second-order potential matrix”. Within the framework of the eikonal approximation the problem reduces to a finite system of first-order coupled integro-differential equations with non-local potentials which depend on the two-body density matrix of the target nucleus. The relationship of the above formulation to the DWIA, the close-coupling method, and the Glauber multiple scattering model is examined. This approach is applied to the elastic and inelastic (2⁺, 4.43 MeV) scattering of 1 GeV nucleons by ¹²C. The corrections to the DWIA are sizeable, and the inelastic scattering appears to be very sensitive to the multi-step contributions and the nuclear structure.     

Deep inelastic Compton scattering and large-p T pion photoproduction in QCD hard collision model

Inclusive photon(pion) production at large-p _T in γp collisions is studied in the framework of QCD perturbation theory, taking into account the effects due to parton transverse momenta. The contributions from various components of photons are equally important at relatively smallp _T (e.g.,p _T?4 Ge V/c at \(\sqrt s = 17GeV\) ). At largep _T, however, the contributions from the subprocesses with direct photon coupling are most important; quark Compton scattering is the dominant subprocess in inelastic Compton scattering.     

Magnitude and alignment of transferred angular momentum in both quasi and deeply inelastic scattering

In-plane and out-of-plane angular correlations of fission fragments in coincidence with projectile-like fragments have been measured for the ⁸⁶Kr + ²³⁸U reaction at 730 MeV. The dependence of the magnitude and alignment of the angular momentum transferred to the fissioning heavy reaction product has been determined. Both quantities decrease strongly with decreasing energy loss in the quasi elastic region, in agreement with the predictions of a transport model.     

Deep inelastic scattering from the nuclear medium

We reexamine deep inelastic scattering from nuclei under assumptions commonly employed in the literature: that quarks remain confined in hadronic constituents of nuclei, that the nuclear cross section is the average of the free-space cross section of hadron i weighted by the probability of finding i in the nucleus, and that there are no final state interactions between the debris of hadron i and the rest of the nucleus. We develop a cluster expansion for the cross section of deep inelastic lepton scattering and the Drell-Yan process on nuclei. Using the “instant” from of dynamics, we find that large contributions to these processes arise from nuclear interactions and correlations. However, our theory differs in detail from other approaches, and we find that binding alone is unlikely to explain the EMC effect. Also, in contrast to many recent papers on the subject, we conclude that the contribution of pions (and other nonnucleonic consistuents of the nucleus) is strongly suppressed.     

Experimental aspects of inelastic nuclear resonance scattering

Hyperfine Interactions - We present an introduction to the technique of inelastic nuclear scattering. The details of experimental setup, instrumentation, and measuring procedure are discussed. The...     

Transport coefficients for deeply inelastic scattering from the Feynman path integral method

Friction and diffusion coefficients can be derived simply by combining statistical arguments with the Feynman path integral method. A transport equation for Feynman's influence functional is obtained, and transport coefficients are deduced from it. The expressions are discussed in the limits of weak, and of strong coupling.     

Resonant enhancement of inelastic light scattering in strongly correlated materials

We use dynamical mean field theory to find an exact solution for inelastic light scattering in strongly correlated materials such as those near a quantum-critical metal-insulator transition. We evaluate the results for q=0 (Raman) scattering and find that resonant effects can be quite large, and yield a double resonance, a significant enhancement of nonresonant scattering peaks, a joint resonance of both peaks when the incident photon frequency is on the order of U, and the appearance of an isosbestic point in all symmetry channels for an intermediate range of incident photon frequencies.     

Relation between nuclear matter and nuclear potential in inelastic alpha—nucleus scattering

Inelastic transition form factors for alpha—nucleus collective excitations are derived from deformed matter distributions by averaging an effective alpha nucleus interaction over the nucleons in the nucleus. The method is an extension of the procedure of calculating the real part of elastic alpha—nucleus potentials from nuclear matter distributions. Numerical examples for the nuclei of ⁴²Ca and ¹⁴²Nd are given. The resulting inelastic form factors depend on the multipolarity of the inelastic excitation and differ from those conventionally derived from a deformed optical potential.     

Shadowing in deep inelastic muon scattering from nuclear targets

Results are presented on the ratio of the inelastic muon-nucleus cross section per nucleon for carbon and calcium relative to that for deuterium. The measurements were made in the kinematic range of low x (0.003–0.1) and low Q² (0.3–3.2 GeV²) at an incident muon energy of 280 GeV. The calcium to deuterium ratio shows a significant x dependence which is interpreted as a shadowing effect. No strong Q² dependence is observed. This suggests that the effect is due at least partially to parton interactions within the nucleus.     

Scaling properties of nuclear shadowing in deep inelastic scattering

We present the perturbative QCD analysis of nuclear shadowing in deep inelastic scattering and prove it to be the scaling, rather than the higher twist, 1/Q², effect, contrary to numerous recent claims. We argue in favor of the scaling triple-pomeron contribution to the nuclear shadowing and comment on the mass spectrum of diffraction excitation by highly virtual photons. Our numerical predictions for shadowing are in good agreement with the recent EMC data.     

Anomalous surface enhanced molecular Raman scattering from inelastic tunneling spectroscopy junctions

Anomalously strong Raman spectra have been obtained from molecular monolayers adsorbed on the insulator in metal-insulator-metal tunnel junctions. We show unambiguously that Raman spectroscopy can readily detect molecular monolayers and consider the effects of surface roughness, the molecule-metal interface and the metal on our results.     

The role of nuclear binding in deep inelastic lepton-nucleon scattering

It is shown that the EMC-effect can be explained by the nuclear structure. The binding of nucleons is shown to play an important role. The contributions of mesons to the nuclear structure functions are discussed.     

Dynamics of metal centers monitored by nuclear inelastic scattering

Nuclear inelastic scattering of synchrotron radiation has been used now since 10 years as a tool for vibrational spectroscopy. This method has turned out especially useful in case of large molecules that contain a Mössbauer active metal center. Recent applications to iron–sulfur proteins, to iron(II) spin crossover complexes and to tin-DNA complexes are discussed. Special emphasis is given to the combination of nuclear inelastic scattering and density functional calculations.     

Colour transparency and scaling properties of nuclear shadowing in deep inelastic scattering

We present the perturbative QCD analysis of nuclear shadowing in the deep inelastic scattering at smallx in terms of the spatial wave function ofq \(\bar q\) fluctuations of virtual photons. The wave function formalism makes it quite obvious that shadowing is the scaling, rather than the higher twist, 1/Q ², effect, contrary to a numerous recent claims. We demonstrate explicitly how the scaling shadowing comes from the large, hadronic, size quarkantiquark pairs even in the limit ofQ ²→∞, and why it should very slowly, ∞1/log (Q ²/m ²) decrease at very largeQ ². We argue in favor of the scaling triple-pomeron contribution to the nuclear shadowing and present predictions for a cross section of diffraction dissociation of virtual photons and for the mass spectrum of diffraction excitation, which can be checked at HERA and Fermilab. We predict strikingly different scaling properties of diffraction dissociation and nuclear shadowing for the longitudinal and transverse photons. Our, numerial predictions for shadowing are in good agreement with the recent EMC data.     

Reaction intermediates in the catalytic Gif-type oxidation from nuclear inelastic scattering

Nuclear inelastic scattering (NIS) of synchrotron radiation, also known as nuclear resonant vibrational spectroscopy (NRVS), has been shown to provide valuable insights into metal-centered vibrations at Mössbauer-active nuclei. We present a study of the iron-centered vibrational density of states (VDOS) during the first step of the Gif-type oxidation of cyclohexene with a novel trinuclear Fe₃(μ₃-O) complex as catalyst precursor. The experiments were carried out on shock-frozen solutions for different combinations of reactants: Fe₃(μ₃-O) in pyridine solution, Fe₃(μ₃-O) plus Zn/acetic acid in pyridine without and with addition of either oxygen or cyclohexene, and Fe₃(μ₃-O)/Zn/acetic acid/pyridine/cyclohexene (reaction mixture) for reaction times of 1 min, 5 min, and 30 min. The projected VDOS of the Fe atoms was calculated on the basis of pseudopotential density functional calculations. Two possible reaction intermediates were identified as [Fe^(III)(C₅H₅N)₂(O₂CCH₃)₂]⁺ and Fe^(II)(C₅H₅N)₄(O₂CCH₃)₂, yielding evidence that NIS (NRVS) allows to identify the presence of iron-centered intermediates also in complex reaction mixtures.