118976257
Quarks and Antiquarks in Nuclei
The Chiral Quark-Soliton model provides the quark and antiquark substructure of the nucleon, which is embedded in nuclear matter. This provides a new way to asses the effects of the nuclear medium on the nucleon. We calculate nuclear binding and saturation, describe the European Muon Collaboration (EMC) effect consistently with Drell-Yan experiments, and predict modifications to the polarized parton distributions. We also calculate the electromagnetic form factors of a bound proton, and find significant modifications of the electromagnetic form factors in the nuclear environment. In every case, the properties of the sea of quark-antiquark pairs in the nucleon are very important, and serve to mitigate the valence quark effect. The changes in the sea quarks when the nucleon is immersed in the nuclear medium are the primary mode by which consistency is maintained with experimental constraints (Drell-Yan data, magnetic moment), while still maintaining a significant effect needed to explain the deep inelastic scattering and polarization transfer data.
119434142
Role of the nuclear vector potential in deep inelastic scattering
We study the influence of the strong nuclear vector potential, treated using the mean-field approximation, in deep inelastic scattering. A physically consistent treatment of the electromagnetic current operator, combined with the use of the operator product expansion is presented and discussed.
120612585
Chiral solitons in nuclei: Saturation, EMC effect, and Drell-Yan experiments
The chiral quark-soliton model of the nucleon contains a mechanism for an attractive interaction between nucleons. This, along with the exchange of vector mesons between nucleons, is used to compute the saturation properties of infinite nuclear matter. This provides a new way to assess the effects of the nuclear medium on a nucleon that includes valence and sea quarks. We show that the model simultaneously describes the nuclear EMC effect and the related Drell-Yan experiments.
121485718
Return of the EMC effect
The relationship between the properties of nuclear matter and structure functions measured in lepton-nucleus deep inelastic scattering is investigated using light front dynamics. We find that relativistic mean field models such as the Walecka, Zimanyi-Moszkowski (and point-coupling versions of the same), and Rusnak-Furnstahl models contain essentially no binding effect, in accord with an earlier calculation by Birse. These models are found to obey the Hugenholtz\char21{}van Hove theorem, which is applicable if nucleons are the only degrees of freedom. Any model in which the entire Fock space wave function can be represented in terms of free nucleons must obey this theorem, which implies that all of the plus momentum is carried by nucleons, and therefore that there will be essentially no binding effect. The explicit presence of nuclear mesons allows one to obtain a modified form of the Hugenholtz\char21{}van Hove theorem, which is equivalent to the often-used momentum sum rule. These results argue in favor of a conclusion that the depletion of the deep inelastic structure function observed in the valence quark regime is due to some interesting effect involving dynamics beyond the conventional nucleon-meson treatment of nuclear physics.
119482861
Chiral solitons in nuclei: Electromagnetic form factors
We calculate the electromagnetic form factors of a bound proton. The chiral quark-soliton model provides the quark and antiquark substructure of the proton, which is embedded in nuclear matter. This procedure yields significant modifications of the form factors in the nuclear environment. The sea quarks are almost completely unaffected, and serve to mitigate the valence quark effect. In particular, the ratio of the isoscalar electric to the isovector magnetic form factor decreases by 20% at Q{sup 2}=1 GeV{sup 2} at nuclear density, and we do not see a strong enhancement of the magnetic moment.
17387311
NNLO Corrections to the Polarized Drell-Yan Coefficient Function
We present the full next-to-next-to-leading order (NNLO) corrections to the coefficient function for the polarized cross section d Δ σ / d Q of the Drell-Yan process. We study the effect of these corrections on the process p + p → l + l − + ‘ X ′ at an C.M. energy S = 200 GeV . All QCD partonic subprocesses have been included provided the lepton pair is created by a virtual photon, which is a valid approximation for a lepton pair invariant mass Q 50 GeV . For this reaction the dominant subprocess is given by q + q ¯ → γ * + ‘ X ′ and its higher order corrections so that it provides us with an excellent tool to measure the polarized sea-quark densities.
118236755
Recent Results in Charmless Hadronic B Decays from BABAR
We report results from five analyses based on data taken with the BABAR detector at the PEP-II asymmetric e{sup +}e{sup -} collider. Included are branching fraction measurements for many B-meson decays involving {eta}, {eta}{prime}, {omega}, {phi} or a{sub 0} mesons and the final state K{sub s}{sup 0}{pi}{sup +}{pi}{sup -}, and a full angular analysis of the decay B{sup 0} {yields} {phi}K*{sup 0}.
1705219
Heavy-quark correlations in deep inelastic scattering
Abstract We discuss some results for heavy quark correlations in next-to-leading order in deep inelastic electroproduction.
123273888
Electromagnetic production of trimuons in deep-inelastic muon scattering
We calculate the cross sections for the electromagnetic contribution to the reaction ..mu.. + N ..-->.. 3..mu.. + N, using the radiative quark-parton model. We discuss some features of the reactions which are expected experimentally, and helpful in distinguishing Compton production from muon radiative production.
119446494
QCD threshold corrections to di-lepton and Higgs rapidity distributions beyond N2LO
Abstract We present threshold enhanced QCD corrections to rapidity distributions of di-leptons in the Drell–Yan process and of Higgs particles in both gluon fusion and bottom quark annihilation processes using Sudakov resummed cross sections. We have used renormalisation group invariance and the mass factorisation theorem that these hard scattering cross sections satisfy as well as Sudakov resummation of QCD amplitudes. We find that these higher order threshold QCD corrections stabilise the theoretical predictions under scale variations.