Related papers: Non-collinearity in high energy processes
Single-spin asymmetries were long thought to vanish in high-energy scattering processes because of their specific time-reversal behavior. Time-reversal-odd phenomena, however, appear naturally when one includes effects of intrinsic…
In this paper we discuss the incorporation of gauge links in hadronic matrix elements that describe the soft hadronic physics in high energy scattering processes. In this description the matrix elements appear in soft correlators and they…
Distribution functions in hard processes can be described by quark-quark correlators, nonlocal matrix elements of quark fields. Color gauge invariance requires inclusion of appropriate gauge links in these correlators. For transverse…
High energy hadronic scattering processes can be described in terms of partonic scattering processes and parton distribution and fragmentation functions. These are bilocal matrix elements of quark operators. Colour gauge-invariance requires…
In these lectures I want to discuss how the structure functions in deep inelastic scattering relate to quark and gluon correlation functions. In particular we will consider the issue of intrinsic transverse momenta of quarks, which becomes…
We investigate the gluon transverse momentum dependent correlators as Fourier transform of matrix elements of nonlocal operator combinations. At the operator level these correlators include both field strength operators and gauge links…
In a high-energy scattering process with hadrons in the initial state, color is involved. Transverse momentum dependent distribution functions (TMDs) describe the quark and gluon distributions in these hadrons in momentum space with the…
We discuss the use of time reversal symmetry in the classification of parton correlators. Specifically, we consider the role of (small) intrinsic transverse momenta in these correlators and the determination of the proper color gauge link.…
Inclusive and semi-inclusive deep inelastic leptoproduction offers possibilities to study details of the quark and gluon structure of hadrons. In many of these experiments polarization is an essential ingredient. We also emphasize the…
The color gauge-invariant transverse momentum dependent (TMD) quark correlators contain process dependent gauge links in the bilocal matrix elements. In this paper, we split these process dependent correlators into universal TMD…
In these lectures I want to discuss how the structure functions in deep inelastic scattering relate to quark and gluon correlation functions. In particular we will consider the issue of intrinsic transverse momenta of quarks, which becomes…
We consider the color gauge invariance of a factorized description of the Drell-Yan process cross section. In particular, we focus on the next-to-leading twist contributions for polarized scattering and on the cross section differential in…
We analyze the Sivers asymmetry in light-cone gauge. The average transverse momentum of the quark distribution is related to the correlation between the quark distribution and the transverse component of the gauge field at $x^-\pm \infty$.…
A better understanding of transverse momentum (k_T-) dependent quark distributions in a hadron is needed to interpret several experimentally observed large angular asymmetries and to clarify the fundamental role of gauge links in…
The effect of perturbative QCD interactions on the high energy scattering of electroweak vector bosons, when the exchanged channel has pion quantum numbers, is considered. The chiral anomaly is shown to appear in the couplings of particular…
Transverse momentum dependent (TMD) parton correlators describing the partonic structure of hadrons contain gauge links, required by color gauge invariance. The required gauge links enter in the matrix elements that contain the parton…
We discuss the transformation of the QCD temporal-gauge Hamiltonian to a representation in which it can be expressed as a functional of gauge-invariant quark and gluon fields. We show how this objective can be realized by implementing the…
When QCD is described by a nonrelativistic effective field theory, operators consisting of gluonic correlators of two chromoelectric or -magnetic fields will often appear in descriptions of quarkonium physics. At zero T, these correlators…
The role of transverse momentum of quarks in semi-inclusive leptoproduction will be discussed. It involves generalized distribution and fragmentation functions which depend on both the longitudinal lightcone momentum fraction of the quarks…
We review applicability of QCD factorization theorem to multiple scattering in deeply inelastic lepton-nucleus scattering. We show why A^{1/3}-type nuclear enhancement can be calculated consistently in perturbative QCD. We derive the…