An overview of the progress regarding the transversity distribution, the tensor charge and other transverse spin distributions will be given. Gluonic analogues will be discussed, as well as
transversity GPDs and GTMDs.
TMD Measurements at high momentum transfer have been carried out in polarized proton-proton collisions at RHIC, in pion induced Drell-Yan scattering off transversely polarized proton targets in COMPASS and in electron-positron annihilation in Belle and BaBar. Available results will be reviewed and the impact of future measurements at RHIC and the SPS will be discussed.
A review of recent SIDIS results about transverse spin and momentum dependent observables will be given. Results that are expected to come in the near future from running experiments will also be discussed.
In this talk, I will present our recent results on nucleon tomography study by utilizing jet observables in various hadronic collisions.
The SIDIS data collected from 2002 to 2010 in COMPASS using a high energy muon beam and transversely polarised proton and deuteron targets, have allowed to performed many unique measurements. In this talk the main results and their interpretation, as well as the new expected measurements, will be reviewed. The need of the more deuteron data and the perspectives from the future COMPASS data...
Correlators such as parton distribution functions (PDFs) exhibit flavor dependence, which is accessible from complementary Semi-Inclusive Deep Inelastic Scattering (SIDIS) measurements with proton and neutron targets. SIDIS off the neutron can be explored using nuclear targets, in particular the deuteron, wherein the quark flavor combination differs from that of the proton. Recent...
In this short talk, we discuss chiral-odd PDFs that can be accessed through dihadron observables: the transversity PDF and the twist-3 scalar PDF e(x).
The former is subject to positivity constraints, the Soffer bound. Recent analyses have explored the role of theoretical constraints on the tensor charge. We comment on that point, in view of future improvements in all global analyses.
As for...
We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back hadron electroproduction, where one hadron is produced in the current fragmentation region and the other in the target fragmentation region. The data were taken with a 10.2 and 10.6 GeV longitudinally polarized electron beam incident on an unpolarized liquid hydrogen target using...
Studies of the properties and the azimuthal distribution of hadrons produced in the Target Fragmentation Region serve as a test of our complete understanding of the different mechanisms in the SIDIS production of hadrons and provide additional information on the QCD dynamics that are not accessible with single hadron production in the Current Fragmentation Region. We present first...
In this talk I will briefly address the state of the art for our understanding of transverse-momentum-dependent distributions, with a focus on their phenomenology. I will introduce some of the topics which are currently under investigation and highlight the fundamental role of the present and future experimental facilities for the advancement of the field.
Single and dihadron fragmentation functions (FFs) are an essential tool in accessing the transverse spin and momentum structure of the nucleon. The chiral-odd FFs provide nearly unique access to the transvsersity distributions and the related tensor charges. Transverse momentum dependent FFs enable the study of various transverse momentum dependent distribution functions in the nucleon....
In semi-inclusive deep inelastic scattering (SIDIS) the non-zero transverse momentum of partons is reflected in the transverse momentum $P_T$ of the produced hadrons. Assuming Gaussian dependence of transverse momentum dependent (TMD) PDFs and fragmentation functions (FFs) upon quark transverse momentum, exponential distribution of $P_T^2$ is expected. In 2016 and 2017, COMPASS experiment at...
The azimuthal asymmetries, given by the amplitudes of the modulations in the azimuthal angle $\phi_{h}$ of the hadrons produced in SIDIS, give access to the Transverse-Momentum-Dependent structure of the nucleon. In unpolarized SIDIS, of particular interest are the $\cos\phi_{h}$ and $\cos2\phi_{h}$ modulations, generated by the Cahn effect and by the Boer-Mulders TMD PDF $h_1^{\perp}$,...
Transverse momentum dependent (TMD) distributions match collinear parton density functions (PDF) in the limit of small transverse distances, which is accounted for by global extractions of TMD distributions. We study the influence of the PDF choice on the determination of unpolarized TMDPDFs and the description of TMD Drell-Yan-pair and Z-boson production data. We find that PDF essentially...
In this talk, I will discuss our update to the global analysis of transverse single-spin asymmetries that now extracts the novel quark-gluon-quark fragmentation function \tilde{H} and explores the role played by the Soffer bound on transversity and lattice QCD computations of the isovector tensor charge.
In this presentation, I will discuss the physics opportunities with the Electron-Ion Collider (EIC) and the current status of the EIC.
Data from Belle Collaboration for associated (with a light unpolarized hadron) and single-inclusive production of transversely polarized $\Lambda$-hyperons in $e^+e^-$ annihilation processes allowed to extract, for the first time, the $\Lambda$ polarizing fragmentation function, by adopting a simplified TMD approach. Recent theoretical developments on the computation of cross sections for...
Extending TMD factorization to thrust-dependent observables entails difficulties ultimately associated with the behavior of soft radiation. As a consequence, the definition of the TMDs has to be revised, while keeping (and extending) its universality properties. Moreover, the regularization of the rapidity divergences intertwines with the thrust dependence, leading to a new kind of...
Soft gluon resummation is essential to obtain precise predictions for QCD processes with more scales involved. The formalism to follow in such scenarios is the Transverse Momentum Dependent factorization theorem. However, for practical applications a Monte Carlo approach is needed. We present the Parton Branching (PB) method- a Monte Carlo approach to obtain QCD collider predictions based on...
Being motivated mainly by the LHC physics, the currently used Monte Carlo Event Generators (MCEGs) lack of the quark spin degree of freedom in their hadronization models, and can not reproduce observed transverse spin effects such as the Collins and the dihadron asymmetries, and longitudinal spin effects such as the jet handedness. To guide the interpretation of SIDIS and $𝑒^+𝑒^−$ data as well...
A key step towards a better understanding of the nucleon structure is the study of Generalized Parton Distributions (GPDs). GPDs are nowadays the object of an intense effort of research since they convey an image of the nucleon structure where the longitudinal momentum and the transverse spatial position of the partons inside the nucleon are correlated. Moreover, GPDs give access to the...
We will report on recent attempts to access universal
GPDs from Deeply virtual Compton scattering and Deeply
virtual meson production.
We discuss the problem of model dependency in the phenomenology of generalised parton distributions (GPDs). We present results of our resent analyses, where we have addressed this problem. This includes the extraction of D-term, which is related to the so-called mechanical properties of the nucleon, and the analysis on the deconvolution of deeply virtual Compton scattering (DVCS) amplitudes. A...
Generalized TMDs (GTMDs) of hadrons are the most general two-parton correlation functions. The Fourier transforms of GTMDs are partonic Wigner functions. During the past few years, several interesting developments have taken place in this field. In this talk, we give a brief overview of these objects and the various developments that has taken place, including, in particular, the...
I will discuss how quarkonium production can be used to probe transverse-momentum-dependent functions (TMDs), and the role played by a new type of non-perturbative functions: the TMD shape functions.
We study the polar and azimuthal decay angular distributions of $J/\psi$ mesons produced in semi-inclusive, deep-inelastic electron-proton scattering. For the description of the quarkonium formation mechanism, we adopt the framework of nonrelativistic QCD, with the inclusion of the intermediate color-octet channels that are suppressed at most by a factor $v^4$ in the velocity parameter $v$...
I will discuss recent calculations of jet correlation and substructure observables relevant for spin asymmetries and nucleon structure
I critically appraise current limitations in precision and accuracy of collinear parton distribution and fragmentation function determination. I focus on open issues related to quantifying data inconsistencies, theoretical uncertainties, and methodological bias. I discuss their relevance in relationship with ongoing and future experimental programs at particle colliders.
We compute the single-spin asymmetry A_UL in semi-inclusive
deep-inelastic scattering of unpolarized leptons and longitudinally polarized
protons at large transverse momentum of the produced hadron. Our calculation is
performed in collinear factorization at the lowest order of QCD perturbation
theory. For photon exchange the asymmetry is T-odd and receives contributions
from the...
I will introduce the problem of the determination of the W boson mass at hadron colliders and the role of non-perturbative effects.
In this talk we present the methodology used in the NNPDF4.0 global analysis. We introduce state of the art techniques in Machine Learning applied to PDF determination, automatised hyperparameter selection and tests to asses the quality and reliability of the methodology.
The entire methodology is open sourced and available for users willing to perform their own PDF analysis.
Some spin observables in the collinear twist-3 formalism will be reviewed.
The STAR Collaboration at RHIC investigates the internal spin structure of the proton with a broad range of measurements in polarized $pp$ collisions. Transverse spin studies aim to elucidate 3D transverse momentum structure and parton transversity. Dijet opening angle measurements are sensitive to the Sivers $\langle k_T \rangle$ and a non-zero spin dependent result in $pp$ collisions is...
Phenomenological analyses of hadron structure from semi-inclusive observables require the use of models to characterize nonperturbative effects, embedded into a formalism of TMD evolution. Constraints provided by pQCD calculations must be imposed in order to maximize predictive power. This is particularly important when attempting to use phenomenological extractions over wide scale...
The TMD factorization at the next-to-leading power has an involved structure of singularities. I discuss the definition and properties of transverse momentum dependent (TMD) distributions of the twist-three including evolution, symmetry relations, parametrization, interpretation, and singularities. I demonstrate that the physical TMD distributions (in terms of which observables are written)...
We present an estimate of the cos$2\phi$ azimuthal asymmetry in back-to-back production of $J/\psi$ and a jet in the process: $e~p\to e~J/\psi~Jet~X$. We calculate the asymmetry using TMD factorization in a generalized parton model (GPM) framework and use non-relativistic QCD (NRQCD) to obtain the $J/\psi$ production rate. We incorporate both color singlet and color octet contributions to the...
An overview of recent results from PHENIX on transverse spin and transverse-momentum-dependent observables will be presented.
Non-perturbative parton distributions that arise in the TMD factorization of cross-sections have dynamics dominated by the lightcone. This renders them inaccessible to direct lattice QCD calculations due to the sign problem in real-time calculations. To circumvent this issue, one may construct a lattice-calculable TMD that shares the same IR physics as the physical TMD appearing in...
There was recent theoretical progress on transverse-momentum-dependent parton distribution functions (TMDs) and parton distribution functions (PDFs) for spin-1 hadrons at twists 3 and 4. We expect that the field of structure functions for spin-1 hadrons will become an interesting topic in 2020's and 2030' due to experimental projects at the Jefferson Laboratory, the Fermilab, the NICA, the...
I will present an overview of recent progress and results in Lattice QCD focusing on the direct measure of moments of the transversity PDF, as well as using the quasi-PDF/GPD approach.
The Collins-Soper kernel describing the rapidity evolution of TMDPDFs is nonperturbative for large transverse separations or small transverse momenta. I will discuss recent lattice QCD calculations that aim to determine the nonperturbative behavior of the quark Collins-Soper kernel.
The investigation of the nucleon spin structure via measurements of dimuons produced in the Drell-Yan process is one of the main goals of the phase-II research program of the COMPASS experiment (M2 beamline, SPS, CERN).
In 2015 and 2018, COMPASS performed Drell-Yan measurements using a 190 GeV/c $\pi^-$ beam impinging on a transversely polarized NH$_3$ target and on an unpolarized tungsten...
After fifty years of investigations, the nucleon structure is still far from being understood and continues to represent a unique test bench for QCD. Despite the enormous progresses achieved in five decades of deep-inelastic scattering (DIS) experiments, a number of crucial open questions are still on the carpet and subject of intense theoretical and experimental studies. In the last two...
Fracture functions describes the hadron production in the target fragmentation region (TFR) in the hard processes, namely -- the spin and transverse momentum dependent correlations between struck parton in the target and produced hadron in TFR.
In this talk I'll shortly describe the formalism and present the theoretical results for SIDIS and Drell-Yan processes.
New experimental results on...
We will discuss recent updates from JAM on gluon polarization in the nucleon and polarized sea asymmetries and the role of the various theoretical constraints, in particular positivity constraints.
I present the study of the TMD distributions of twist-three. It includes definition, interpretation, symmetry properties, and LO evolution equations. I show that the evolution of twist-three TMD distributions is essentially simplified in the large-Nc limit.
I discuss different aspects of the interplay between determinations of Parton Distribution Functions and constraints of Effective Field Theories based on fits collider data.
We investigate the photoproduction of quarkonium pairs at EIC kinematical region by exploring the contributions from single-parton scatterings and double-parton scatterings. The NRQCD framework is used for the quarkonium formation mechanism.
Transverse-momentum dependent parton distributions are genuine non-perturbative functions that describe the 3-dimensional structure of a hadron. These distributions should be extracted from data. However, even if one restricts himself to the leading power distributions, eight of them has to be considered. A way to reduce the complexity, they can be evaluated in a model-independent way in...
An overview of recent results from PHENIX on transverse spin and transverse-momentum-dependent observables will be presented.
An overview of recent results from PHENIX on transverse spin and transverse-momentum-dependent observables will be presented.
