Related papers: Transversely polarized Drell-Yan measurements at C…
The 160 GeV polarised muon beam available at CERN, with positive or negative charge, makes COMPASS a unique place for GPD studies. The first GPD related COMPASS results come from exclusive vector meson production on transversely polarised…
The COMPASS Collaboration is measuring the asymmetries in the azimuthal distributions of positive and negative hadrons produced in Deep Inelastic Scattering (DIS) on unpolarized protons. The data have been collected in 2016 and 2017 with a…
We estimate the single-spin asymmetries (SSA) which provide the access to transversity as well as to Boer-Mulders and Sivers PDFs via investigation of the single-polarized Drell-Yan (DY) processes with $ pp$, $pD$ and $DD$ collisions…
Azimuthal Asymmetries in unpolarized SIDIS can be used to probe the transverse momentum of quarks inside the nucleon. Furthermore, they give access to the so-far unmeasured Boer-Mulders function. We report on the first measurement of…
We examine in detail the diagrammatic mechanisms which provide the change of sign between the single transverse spin asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) and in the Drell-Yan process (DY). This asymmetry…
We calculate the gauge invariant Drell-Yan-like hadron tensors. In connection with new COMPASS results, we propose the single spin asymmetry which probes gluon poles together with chiral-odd and time-odd functions. The relevant pion…
First measurements of azimuthal asymmetries in hadron-pair production in deep-inelastic scattering of muons on transversely polarised ^6LiD (deuteron) and NH_3 (proton) targets are presented. The data were taken in the years 2002-2004 and…
Recently, a reconsideration of Drell-Yan cross sections at moderate energies and masses has suggested the possibility of relevant enhancements of the cross sections in some kinematical regions. If confirmed, these predictions could largely…
In 2022, the COMPASS collaboration performed semi-inclusive measurements of deep-inelastic muon-scattering on a transversely polarised deuteron (6LiD) target. From these data, transverse-spin-dependent dihadron asymmetries are extracted…
After reviewing the most important COMPASS results on transverse spin effects in SIDIS, I will present the recent work we have done on weighted Sivers asymmetries and "transversity induced" $\Lambda$ polarisation. Using the high statistics…
Accessing the Sivers TMD function in proton+proton collisions through the measurement of transverse single spin asymmetries (TSSAs) in Drell-Yan and weak boson production is an effective path to test the fundamental QCD prediction of the…
We compute all the leading-twist azimuthal spin asymmetries in the pion-proton induced Drell-Yan process. These spin asymmetries arise from convolutions of the leading-twist transverse-momentum-dependent parton distributions (TMDs) of both…
Although the proton was discovered about 100 years ago, its spin structure still remains a mystery. Recent studies suggest that the orbital angular momentum of sea quarks could significantly contribute to the proton's spin. The SeaQuest…
We calculate the hadron tensor related to the photon-induced Drell-Yan process, with incoming nucleon being transversally polarised. We predict the new single spin asymmetry which probes gluon poles and which is expressed in terms of photon…
The inclusive A_1,p and hadron double-spin asymmetries A_p^pi+, A_p^pi-, A_p^K+, A_p^K- measured at COMPASS (CERN SPS) in deep-inelastic scattering of a polarized muon beam off a polarized NH_3 solid target are presented. The results have…
We consider semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan events within transverse momentum dependent (TMD) factorization. Based on the simultaneous fit of multiple data points, we extract the unpolarized TMD distributions…
We present next-to-leading order predictions for double transverse-spin asymmetries in Drell--Yan dilepton production initiated by proton--antiproton scattering. The kinematic region of the proposed PAX experiment at GSI:…
We study single-spin asymmetries in semi-inclusive deep inelastic scattering with transversely polarized target. Based on the QCD factorization approach, we consider Sivers and Collins contributions to the asymmetries. We fit simple…
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…
We show that for Drell-Yan events by unpolarized hadronic projectiles and nuclear targets, azimuthal asymmetries can arise from the nuclear distortion of the hadronic projectile wave function, typically a spin-orbit effect occurring on the…