Energy Loss Effect in High Energy Nuclear Drell-Yan Process

The energy loss effect in nuclear matter, which is another nuclear effect apart from the nuclear effect on the parton distribution as in deep inelastic scattering process, can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of the nuclear parton distribution studied only with lepton deep inelastic scattering experimental data, measured Drell-Yan production cross sections for 800GeV proton incident on a variety of nuclear targets are analyzed within Glauber framework which takes into account energy loss of the beam proton. It is shown that the theoretical results with considering the energy loss effect are in good agreement with the FNAL E866

Nuclear Shadowing in a Parton Recombination Model

Deep inelastic structure functions $F_2^A(x)$ are investigated in a $Q^2$ rescaling model with parton recombination effects. We find that the model can explain experimentally measured $F_2^A(x)$ structure functions reasonably well in the wide Bjorken$-x$ range ($0.005<x<0.8$). In the very small $x$ region ($x<0.02$), recombination results are very sensitive to input sea-quark and gluon distributions.Comment: preprint MKPH-T-93-04, IU/NTC 92-20, 25 pages, TEX file (without Figs. 1-14)., (address after April 1: Saga U., Japan

Pions in the nuclear medium and Drell-Yan scattering

We investigate the modification of the pion-cloud in the nuclear medium and its effect on the nuclear Drell-Yan process. The pion's in-medium self-energy is calculated in a self-consistent delta-hole model, with particle-hole contribution also included. Both the imaginary and real part of the pion's and delta's self-energy are taken into account and related through a dispersion relation assuring causality. The resulting in-medium pion light-cone momentum distribution shows only a slight enhancement compared to the one of the free nucleon. As a consequence the ratio of the cross-section for Drell-Yan scattering on nuclear matter and nucleonic target is close to unity in agreement with experiment.Comment: 33 pages, Latex with epsf, figures included, to appear in Phys. Rev.

Making a Net Zero Society - Follow the Social Science. Summary report

The Economic and Social Research Council-funded ACCESS network drew together an independent task force of experts to consider the role of social science in UK net zero policy. The task force, which ran for one year between 2023-2024, reviewed a range of social science perspectives, analysed examples of government net zero plans and built understanding from case studies of societal change. We now call upon government to make more consistent and effective use of social science in delivering UK net zero ambitions. Our work shows the huge opportunities, and wide range of benefits, that can be delivered through sustained action to reduce demand for energy. To achieve net zero we need actors from across society to be engaged. Actors that work at the mid-level, between scales, silos and sectors, are especially important. Engaging citizens in meaningful debate about change and generating positive visions of a net zero future will also be essential. We recommend that government establish a Net Zero Social Science Advisory Committee in the Department of Energy Security and Net Zero.Economic and Social Research Council (ESRC)Leverhulme Trus

Instantons And Baryon Mass Splittings in the MIT Bag Model

The contribution of instanton-induced effective inter-quark interactions to the baryon mass splittings was considered in the bag model. It is found that results are different from those obtained in the constituent quark model where the instanton effects are like those from one-gluon exchange. This is because in the context of the bag model calculation the one-body instanton-induced interaction has to be included.Comment: 23 pages, report ZTF-93/10 (to appear in Phys.Rev. D

A Proposed Test of Charge Symmetry in Σ\Sigma Decay

The semi-leptonic decays of $\Sigma^\pm$ offer a vehicle for observing charge symmetry-breaking. The effect is expected to be about 6\%, enhanced due to the replacement of two u quarks by d quarks. We propose that present experimental data be improved to search for this effect.Comment: 6 pages, submitted to Physical Review D, Brief Reports, Report # DOE/ER/40427-14-N9

Return of the EMC Effect: Finite Nuclei

A light front formalism for deep inelastic lepton scattering from finite nuclei is developed. In particular, the nucleon plus momentum distribution and a finite system analog of the Hugenholtz-van Hove theorem are presented. Using a relativistic mean field model, numerical results for the plus momentum distribution and ratio of bound to free nucleon structure functions for Oxygen, Calcium and Lead are given. We show that we can incorporate light front physics with excellent accuracy while using easily computed equal time wavefunctions. Assuming nucleon structure is not modified in-medium we find that the calculations are not consistent with the binding effect apparent in the data not only in the magnitude of the effect, but in the dependence on the number of nucleons.Comment: 11 pages, 6 figure

Pion Excess, Nuclear Correlations, and the Interpretation of (p⃗,n⃗\vec p, \vec n) Spin Transfer Experiments

Conventional theories of nuclear interactions predict a net increase in the distribution of virtual pions in nuclei relative to free nucleons. Analysis of data from several nuclear experiments has led to claims of evidence against such a pion excess. These conclusions are usually based on a collective theory (RPA) of the pions, which may be inadequate. The issue is the energy dependence of the nuclear response, which differs for theories with strong NN correlations from the RPA predictions. In the present paper, information about the energy dependence is extracted from sum rules, which are calculated for such a correlated, noncollective nuclear theory. The results lead to much reduced sensitivity of nuclear reactions to the correlations that are responsible for the pion excess. The primary example is $(\vec p,\vec n)$ spin transfer, for which the expected effects are found to be smaller than the experimental uncertainties. The analysis has consequences for Deep Inelastic Scattering (DIS) experiments as well.Comment: 16 pages, LaTeX, no figures, submitted to Phys. Rev.

A Light Front Treatment of the Nucleus-Implications for Deep Inelastic Scattering

A light front treatment of the nuclear wave function is developed and applied, using the mean field approximation, to infinite nuclear matter. The nuclear mesons are shown to carry about a third of the nuclear plus momentum, p+; but their momentum distribution has support only at p+ =0, and the mesons do not contribute to nuclear deep inelastic scattering. This zero mode effect occurs because the meson fields are independent of space-time position.Comment: 11 pages, revtex, 1 figur