Related papers: Recent Cold QCD Results from STAR
In this contribution, we will present a short overview of the transverse momentum dependent (TMD) approach as a tool for studying the 3-dimensional structure of hadrons in high-energy (un)polarized hadron collisions. We will then summarize…
We study the transverse single-spin asymmetry for single-hadron production in proton-proton collisions within the framework of collinear twist-3 factorization in Quantum Chromodynamics. By taking into account the contribution due to parton…
We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse momentum dependent parton distribution functions…
We develop the theoretical framework needed to study the distribution of hadrons with general polarization inside jets, with and without transverse momentum measured with respect to the standard jet axis. The key development in this paper,…
We initiate the study of transverse momentum-dependent (TMD) fragmentation functions for heavy quarks, demonstrate their factorization in terms of novel nonperturbative matrix elements in heavy-quark effective theory (HQET), and prove new…
We evaluate the pion and kaon transverse momentum dependent parton distribution functions (TMDPDFs) in the instanton liquid model (ILM), a model of the QCD vacuum at low resolution. The relevant TMDs are factored into a constituent quark…
Using a generalized parton model approach including spin and intrinsic parton motion effects, and assuming the validity of factorization for large pT jet production in hadronic collisions, we study the azimuthal distribution around the jet…
An azimuthal dependence of pions produced in polarized Deep Inelastic Scattering, gamma^* - p(transv. polarized) -> pion + X, has been recently observed and might be related to the so-called Collins effect. We discuss in details, for a…
We investigate the nucleon tensor charge from current experiments by a combined analysis of the Collins asymmetries in two hadron production in $e^+e^-$ annihilations and semi-inclusive hadron production in deep inelastic scattering…
Preliminary results obtained by the COMPASS experiment for longitudinal-spin-dependent azimuthal asymmetries in single-hadron muoproduction off protons are presented for the first time. The analysis was carried out on the full data sample…
We present a global analysis of Sivers functions, transversity distribution functions, and Collins fragmentation functions within the transverse momentum dependent factorization. This analysis encompasses the latest data from semi-inclusive…
The STAR experiment at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is carrying out a spin physics program colliding transverse or longitudinal polarized proton beams at $\sqrt{s}=200-500 $GeV to gain a…
We study the leading-power gluon transverse momentum dependent distributions (TMDs) of relevance to the study of asymmetries in the scattering off transversely polarized hadrons. Next-to-leading-order perturbative calculations of these TMDs…
We investigate the use of jets to measure transverse momentum dependent distributions (TMDs). The example we use to present our framework is the dijet momentum decorrelation at lepton colliders. Translating this momentum decorrelation into…
The STAR collaboration has reported precision measurements on the transverse single spin asymmetries for the production of forward $\pi^0$ mesons from polarized proton collisions at the center of mass energy of 200 GeV. Disentangling…
The STAR experiment at RHIC is carrying out a comprehensive high-energy spin physics program to understand the internal structure and dynamics of the proton in polarized proton-proton collisions at $\sqrt{s} = 200$ GeV and $\sqrt{s} =…
In 2015 the first collisions between polarized protons and nuclei occurred at the Relativistic Heavy Ion Collider (RHIC), at a center-of-mass energy of $\sqrt{s_{NN}}=200$ GeV. Comparisons between spin asymmetries and cross-sections in…
Approximate relations among transverse momentum dependent quark distribution functions are established in the framework of the QCD parton model. The validity of such results survives QCD evolution effects, owing to the Politzer theorem on…
The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV positive muon beam and a transversely polarised NH_3 target. The…
In semi-inclusive DIS of polarized leptons on a transversely polarized target eight azimuthal modulations appear in the cross-section. Within QCD parton model four azimuthal asymmetries can be interpreted at leading order, two of them being…