121347456
On nucleon parton distributions from the chiral quark-soliton model
119292449
Nuclear physics with a medium-energy Electron-Ion Collider
A polarized ep/eA collider (Electron-Ion Collider, or EIC) with variable center-of-mass energy √s ∼ 20–70 GeV and luminosity ∼1034 cm−2 s−1 would be uniquely suited to address several outstanding questions of Quantum Chromodynamics (QCD) and the microscopic structure of hadrons and nuclei: i) the three-dimensional structure of the nucleon in QCD (sea quark and gluon spatial distributions, orbital motion, polarization, correlations); ii) the fundamental color fields in nuclei (nuclear parton densities, shadowing, coherence effects, color transparency); iii) the conversion of color charge to hadrons (fragmentation, parton propagation through matter, in-medium jets). We briefly review the conceptual aspects of these questions and the measurements that would address them, emphasizing the qualitatively new information that could be obtained with the collider. Such a medium-energy EIC could be realized at Jefferson Lab after the 12GeV Upgrade (MEIC), or at Brookhaven National Lab as the low-energy stage of eRHIC.
4600129
Off - forward quark distributions of the nucleon in the large N(c) limit
We study the off-forward quark distributions (OFQD's) in the chiral quark-soliton model of the nucleon. This model is based on the large-${N}_{c}$ picture of the nucleon as a soliton of the effective chiral Lagrangian and allows one to calculate the leading twist quark and antiquark distributions at a low normalization point. We demonstrate the consistency of the approach by checking various sum rules for the OFQD's. We present numerical estimates of the isosinglet distribution $H(x,\ensuremath{\xi},{\ensuremath{\Delta}}^{2})$. In contrast with other approaches we find a strong qualitative dependence on the longitudinal momentum transfer, $\ensuremath{\xi}$. In particular, $H(x,\ensuremath{\xi},{\ensuremath{\Delta}}^{2})$ as a function of $x$ exhibits fast crossovers at $|x|=\ensuremath{\xi}/2$. Such behavior could lead to a considerable enhancement of the deeply virtual Compton scattering cross section.
16801030
Polarized antiquark flavor asymmetry in Drell–Yan pair production
Abstract. We investigate the role of the flavor asymmetry of the nucleon's polarized antiquark distributions in Drell–Yan lepton pair production in polarized nucleon–nucleon collisions at HERA (fixed–target) and RHIC energies. It is shown that the large polarized antiquark flavor asymmetry predicted by model calculations in the large–$N_c$ limit (chiral quark–soliton model) has a dramatic effect on the double spin asymmetries in high mass lepton pair production, as well as on the single spin asymmetries in lepton pair production through $W^\pm$–bosons at $M^2 = M_W^2$.
17230719
Chiral Lagrangian for excited pions
We construct a chiral Lagrangian containing, in addition to the usual pion field ({pi}), also its first radial excitation ({pi}{sup {prime}}). The Lagrangian is derived in the large-N{sub c} limit from a Nambu{endash}Jona-Lasinio (NJL) quark model with separable nonlocal interactions, with form factors corresponding to three-dimensional ground- and excited-state wave functions. Chiral symmetry breaking is governed by the NJL gap equation. The effective Lagrangian for {pi} and {pi}{sup {prime}} mesons shows the decoupling of the Goldstone pion and the vanishing of the {pi}{sup {prime}} leptonic decay constant f{sub {pi}{sup {prime}}} in the chiral limit, as required by axial-vector current conservation. We derive the excited-state contribution to the axial-vector current of the model using Noether{close_quote}s theorem. For a finite pion mass and {pi}{sup {prime}} masses in the range of 750{endash}1300 MeV, f{sub {pi}{sup {prime}}}/f{sub {pi}} is found to be of the order of 1{percent}. {copyright} {ital 1997} {ital The American Physical Society}
15375029
SMALL-x PHYSICS: From HERA to LHC and Beyond
▪ Abstract We summarize the lessons learned from studies of hard scattering processes in high-energy electron-proton collisions at HERA and antiproton-proton collisions at the Tevatron, with the ai...
22188300
Differences between mean-field dynamics and N-particle quantum dynamics as a signature of entanglement.
A Bose-Einstein condensate in a tilted double-well potential under the influence of time-periodic potential differences is investigated in the regime where the mean-field (Gross-Pitaevskii) dynamics become chaotic. For some parameters near stable regions, even averaging over several condensate oscillations does not remove the differences between mean-field and N-particle results. While introducing decoherence via piecewise deterministic processes reduces those differences, they are due to the emergence of mesoscopic entangled states in the chaotic regime.