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We report progresses on leading-twist transverse-momentum-dependent (TMD) gluon distributions, calculated in a spectator-model framework for the parent nucleon. We encode in our formalism a fit-based parameterization for the spectator-mass density, suited to describe the gluon content of the proton in a wide range of $x$. We present preliminary results on the $f$-type Sivers function, a key ingredient to access relevant spin-asymmetries emerging when the nucleon is transversely polarized. These studies are helpful to shed light on the gluon dynamics inside nucleons and nuclei, which is one of the primary goals of new-generation colliding facilities, as the Electron-Ion Collider, the High-Luminosity LHC, NICA-SPD, and the Forward Physics Facility., 6 pages, 2 figures. Presented by F.G. Celiberto at the European Physical Society Conference on High Energy Physics (EPS-HEP2021), 26-30 July 2021; version accepted for publication in the conference proceedings by PoS

We present preliminary results on the leading-twist transverse-momentum-dependent (TMD) gluon linearity function, which is directly connected to nucleon transverse-spin asymmetries originating from the density of linearly-polarized gluons. The function is calculated in a spectator-model framework for the parent proton and for the $f$-type gauge-link structure. Our work represents a further step toward the definition of a complete set of gluon TMD distributions at twist-2 that can be used to access the gluon dynamics inside nucleons and nuclei at new-generation colliders., Comment: 5 pages, 1 figure. Presented by F.G. Celiberto at the 22nd Particles and Nuclei International Conference (PANIC2021), 5-10 September 2021; version accepted for publication in the conference proceedings by PoS

We present the first extraction of the transversity distribution based on the global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important among other things for detecting possible signals of new physics in high-precision low-energy experiments., Talk presented at CIPANP 2018. 9 pages, LaTeX, 4 double figures in pdf

We present the first extraction of the transversity distribution based on the global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important among other things for detecting possible signals of new physics in high-precision low-energy experiments.

The transversity was recently extracted from data on the production of hadron pairs in semi-inclusive deep-inelastic scattering. This analysis can be conveniently performed in the framework of collinear factorization where the elementary mechanism is represented by the simple product of transversity and of a suitable chiral-odd function describing the fragmentation of a transversely polarized parton into a pair of hadrons inside the same current jet. The same elementary mechanism was predicted long ago to generate an asymmetry in the azimuthal distribution of the hadron pairs when they are produced in proton-proton collisions with one transversely polarized proton. Recently, the STAR Collaboration has observed this asymmetry. We analyze the impact of these data on our knowledge of transversity and we present its first preliminary extraction from a global fit of all data in hard processes with inclusive di-hadron production., Comment: 7 pages, 2 multiple figures, PoS style, adapted from the proceedings of the XXV International Workshop on Deep-Inelastic Scattering and Related Subjects, 3-7 April 2017, Univ. of Birmingham (UK)

In these proceedings, we propose an extraction of the valence transversity parton distributions. Based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets, this extraction of transversity is performed in the framework of collinear factorization. The recently released data for proton and deuteron targets at HERMES and COMPASS allow for a flavor separation of the valence transversities, for which we give a complete statistical study., To appear in the proceedings of the XXI International Workshop on Deep-Inelastic Scattering and Related Subjects 22-26 April 2013, Marseilles, France. To be published in PoS. Includes PoS.cls

The determination of quark angular momentum requires the knowledge of the generalized parton distribution $E$ in the forward limit. We assume a connection between this function and the Sivers transverse-momentum distribution, based on model calculations and theoretical considerations. Using this assumption, we show that it is possible to fit at the same time nucleon anomalous magnetic moments and semi-inclusive single-spin asymmetries. This imposes additional constraints on the Sivers function and opens a plausible way to quantifying the quark angular momentum., 4 pages, RevTeX style, 2 figures: updated version of fig.2, extended references accordingly; based on the proceedings of "XX International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2012)", March 26-30 2012, Bonn (Germany), and of "Sixth International Conference on Quarks and Nuclear Physics (QNP2012)", April 16-20 2012, Palaiseau (France)