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This talk summarizes recent progress in top quark physics studies for high energy linear electron-positron colliders as presented at the LCWS2000 Workshop at Fermilab. New results were presented for top pair production at threshold and in the continuum, as well as for top production at γγ colliders.
The transverse polarization (or transversity) distributions ∆T q(x), introduced 20 years ago by Ralston and Soper [1] and studied in more detail in the last decade [2], are one of the three sets of leading-twist quark and antiquark distribution functions – the other two are the momentum distributions q(x) and the helicity distributions ∆q(x). (Note that ∆T q is often called h1). Formally ∆T q i...
Article history: Received 9 October 2015 Received in revised form 20 November 2015 Accepted 14 December 2015 Available online 17 December 2015
A particularly simple confinement scenario [1] is available in the minimal Coulomb gauge. It attributes confinement of color to the long range of the color-Coulomb potential Vcoul(R). This quantity is the instantaneous part of the 4-4 component of the gluon propagator, Dμν(x) ≡ 〈gAμ(x) gAν(0)〉, namely D44(x, t) = Vcoul(|x|)δ(t) +P (x, t). The vacuum polarization term P (x, t) is less singular t...
The motion of quark is studied in a confining bag having central color field. The Dirac equation is solved for a quark in such bag and its energy spectrum is found. It is pointed out the possibility to identify the external color field with the background field of gluon condensation. This makes the received energy spectrum of quark useful for comparison with the energy spectrum of hadrons.
A realistic hyperon (Y )-nucleon (N) interaction based on the quark model and the oneboson-exchange potential is constructed. The Nijmegen potential model D with the SU(3) flavor symmetry is modified with a quark exchange interaction at the short-distance, which replaces the short-range repulsive core in the original model. The flavor-spin dependences of the short-range repulsion are qualitativ...
We study the modification of the multiplicity distributions in MLLA due to the presence of a QCD medium. The medium is introduced though a multiplicative constant (fmed) in the soft infrared parts of the kernels of QCD evolution equations. Using the asymptotic ansatz for quark and gluons mean multiplicities 〈nG〉 = e γy and 〈nQ〉 = r e respectively, we study two cases: fixed γ as previously consi...
We considered the quark-meson coupling model for a nucleon. The model describes a nucleon as an MIT bag, in which quarks are coupled to the scalar and the vector mesons. A set of coupled equations for the quark and the meson fields are obtained and are solved in a self-consistent manner. We show that the mass of a dressed MIT bag interacting with σand ω-meson fields differs considerably from th...
We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. We discuss the basic concepts of the method, including renormalization of the gauge link. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.
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