Related papers: Transversity distributions and Drell-Yan spin asym…
We consider the azimuthal distribution of the final observed hadron in semi-inclusive deep-inelastic scattering and the lepton pair in the Drell-Yan process. In particular, we focus on the $\cos \phi$ modulation of the unpolarized cross…
Flavor asymmetry is investigated in polarized light-antiquark distributions by a meson-cloud model. In particular, rho meson contributions to Delta u-bar - Delta d-bar are calculated. We point out that the g_2 part of rho contributes to the…
In order to test the NMC finding of flavor asymmetry $\overline u-\overline d$ in the nucleon, existing Drell-Yan data for the tungsten target are often used. However, we have to be careful in comparing nuclear data with the nucleon ones.…
SU(3), baryon octets and a meson cloud model are compared for the flavor asymmetry of sea quarks in the $\Sigma^+$, as an example. Large differences are found, especially between SU(3) and the meson cloud model. We suggest Drell-Yan…
We investigate the Sivers asymmetry in the pion-induced single polarized Drell-Yan process in the theoretical framework of the transverse momentum dependent factorization up to next-to-leading logarithmic order of QCD. Within the TMD…
Proton transverse-spin azimuthal asymmetries are extracted from the COMPASS 2010 semi-inclusive hadron measurements in deep inelastic muon-nucleon scattering in those four regions of the photon virtuality $Q^2$, which correspond to the four…
We investigate the role of the transverse spin dependence in Drell Yan lepton pair production to NLO in QCD at parton level. In our analysis we deal with the large $p_T$ distributions. We give very compact expressions for the virtual…
We discuss the effects of so-called gluonic poles in twist-three hadronic matrix elements, as first considered by Qiu and Sterman, in the Drell-Yan process. These effects cannot be distinguished from those of time-reversal odd distribution…
We consider the leading and sub-leading twist $T$-odd and even contributions to the $\cos 2\phi$ azimuthal asymmetry in unpolarized dilepton production in Drell-Yan Scattering. We estimate the contributions' effects at $500 {\rm GeV}$, $ 50…
New possibilities arising from the availability at GSI of antiproton beams, possibly polarised, are discussed. The investigation of the nucleon structure can be boosted by accessing in Drell-Yan processes experimental asymmetries related to…
I shall present a rather pedagogical discussion of the transversity distributions in the quark-parton model and, in particular, the role of perturbative QCD corrections. Among the topics I shall discuss are: LO and NLO evolution, the Soffer…
We calculate the next-to-leading order perturbative QCD corrections to the transverse momentum weighted single transverse spin asymmetry in Drell-Yan lepton pair production in hadronic collisions. We identify the splitting function relevant…
Taking into account the effect of final state interaction, we calculate the non-zero (na\"{i}ve) $T$-odd transverse momentum dependent distribution $h_1^{\perp}(x,\kp^2)$ of the pion in a quark-spectator-antiquark model with effective…
The Drell-Yan massive lepton-pair production in hadronic collisions provides a unique tool complementary to the Deep-Inelastic Scattering for probing the partonic substructures in hadrons. We review key concepts, approximations, and…
In this paper, we extend the study of Drell-Yan processes with antiproton beams already presented in a previous work. We consider the fully polarized $\bar{p}^\uparrow p^\uparrow \to \mu^+ \mu^- X$ process, because this is the simplest…
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three azimuthal…
Polarized flavor asymmetry Delta u-bar/Delta d-bar is investigated in a meson-cloud model. A polarized nucleon splits into a rho meson and a baryon, then the polarized rho meson interacts with the virtual photon. Because of the difference…
The flavor asymmetry of the unpolarized antiquark distributions in the proton, dbar(x) - ubar(x) > 0, can qualitatively be explained either by Pauli blocking by the valence quarks, or as an effect of the pion cloud of the nucleon. In…
The Drell-Yan process is studied in the framework of TMD factorization in the Sudakov region $s\gg Q^2\gg q_\perp^2$ corresponding to recent LHC experiments with $Q^2$ of order of mass of Z-boson and transverse momentum of DY pair $\sim$…
We explain a gluon transversity, transverse-momentum-dependent parton distribution functions (TMDs), and parton distribution functions (PDFs) for spin-1 hadrons. The gluon transversity exists in hadrons with spin more than or equal to one,…