120351727
An MIT bag model on S3
Abstract We study an MIT bag on a three-dimensional hypersphere, S 3 ( L ), as a model for baryons at finite density. First we construct the solutions of the free Dirac equation on S 3 . We then study a model where the quarks are confined to an MIT bag occupying a sector of S 3 , while the complementary sector is filled with non-perturbative vacuum. The energy and size of such a bag are studied as a function of the hypersphere radius, i.e., the average baryon density. This system, where the non-perturbative vacuum is described by a volume energy, B , does not go to a completely perturbative phase at high densities. We argue that this behaviour is related to a general instability of the MIT bag with respect to formation of small volumes of non-perturbative vacuum inside a bag and suggest additional non-volume terms for the vacuum energy to avoid this problem. This model does, however, show a transition from a three-quark to a six-quark ground state at high densities, which indicates its approach to chiral-symmetry restoration and deconfinement.
125666710
Nucleon matrix elements of twist - three and twist -4 operators from the instanton vacuum
121347456
On nucleon parton distributions from the chiral quark-soliton model
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...
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.
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 $M^2 = M_W^2$.
27937897
Creation and detection of a mesoscopic gas in a nonlocal quantum superposition.
We investigate the scattering of a quantum matter wave soliton on a barrier in a one-dimensional geometry, and we show that it can lead to mesoscopic quantum superposition states, where the atomic gas is in a coherent superposition of being in the half-space to the left of the barrier and being in the half-space to the right of the barrier. We propose an interferometric method to reveal the coherent nature of this superposition, and we discuss in detail the experimental feasibility.