### Conveners

#### TMDs

- Carlota Andres (Ecole Polytechnique, CPHT)

#### TMDs: Next-to-leading power

- Carlota Andres (Ecole Polytechnique, CPHT)

#### TMDs: Global extractions

- Jack Holguin (CPHT Ecole Polytechnique)

#### TMDs: Global extractions

- Jack Holguin (CPHT Ecole Polytechnique)

#### TMDs: Fragmentation

- Maxim Nefedov (IJClab, Orsay)

#### TMDs: Small-x

- Maxim Nefedov (IJClab, Orsay)

#### TMDs: Quarkonium

- Cyrille Marquet (CPHT - Ecole Polytechnique)

Parametrizing TMD parton densities and fragmentation functions in ways that consistently match their large transverse momentum behavior in standard collinear factorization has remained notoriously difficult. We show how the problem is solved using a recently introduced set of steps for combining perturbative and nonperturbative transverse momentum in TMD factorization. In this ``hadron...

The transverse momentum dependent (TMD) factorization describes the traverse-momentum differential cross-section in the limit of large virtuality of the probe and fixed other scales. To extend the description to a broader range of scales, one needs to incorporate power corrections. I present an overview of the recent development of power corrections to the TMD factorization, including the...

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...

In this work we describe how TMD Jet distributions are defined at NLP in a $q_T/Q$ expansion. These distributions are twist-3 distributions that contribute to SIDIS and $e^+e^-$ processes. We find that description of NLP contributions using jets in the large-$R$ limit significantly simplifies the discussion. Here we show what are the LO contributions to the twist-3 jets and cancellation of...

I will report on recent QCD global analyses of single-spin asymmetries involving two different types of observables. On the one hand, measurements of the Sivers, Collins, and sin(phi_S) effects in SIDIS, Collins effect in electron-positron annihilation, Sivers effect in Drell-Yan, and A_N in single-inclusive proton-proton collisions, are sensitive to important TMDs and collinear twist-3...

In this talk we present the latest results of the MAP collaboration about the extraction of Transverse-Momentum-Dependent (TMD) distributions at the N$^3$LL logarithmic accuracy. We discuss the extraction of unpolarized quark TMD Parton Distribution Functions (TMD PDFs) in the proton and in the pion, as well as TMD Fragmentation Functions (TMD FFs), from global fits of Drell-Yan and...

The factorization theorem plays an important role in the analysis of high energy quantum chromodynamic (QCD) processes, separating the nonperturbative hadronic interaction into the universal parton distribution functions (PDFs) and fragmentation functions (FFs) and the process-dependent interactions into short distance perturbative calculations, with any interference power suppressed. With a...

In this talk, we will present a recent re-analysis of Belle data for the transverse $\Lambda$ and $\bar{\Lambda}$ polarization in $e^+e^-$ annihilation processes within a TMD factorization approach and adopting the CSS framework.

We will also discuss the issue of isospin symmetry and the role of the charm quark contribution, with their impact on the description of the experimental data as...

In global extractions of transverse momentum dependent (TMD) distributions, the TMDs match the collinear parton density functions (PDF) in the limit of small transverse distances. The use of different PDF sets is one of the sources of discrepancy among TMD sets available. In this talk we discuss the influence of the PDF choice on the determination of unpolarized TMDPDFs and the description of...

Extending the TMD factorization to thrust-dependent observables entails difficulties ultimately associated with the behavior of soft radiation.

In this talk, the factorization properties of the thrust distribution of $e^+e^−$ annihilation into a single hadron are discussed and their peculiarities with respect to standard TMD factorization are highlighted.

I present the phenomenological...

The DGLAP evolution equations are arguably the most important evolution equations for collider physics applications. However, DGLAP doesn’t capture correlations in fragmentation, which e.g. enter in dihadron fragmentation or the study of energy flow within jets. In this talk I present a general non-linear collinear evolution equation, that accounts for these correlations. We have calculated...

Typically, a production of a particle with a small transverse momentum in hadron-hadron collisions is described

by CSS-based TMD factorization at moderate Bjorken $x_B\sim 1$ and by $k_T$-factorization at small $x_B$.

A uniform description valid for all $x_B$ is provided by rapidity-only TMD factorization developed in a series

of recent papers at the tree level. In this paper the ...

The ”tomography” of the proton and heavy nuclei, which refers to the three-dimensional imaging of elementary quarks and gluons in these QCD bound states, is one the primary goal of the future Electron-Ion Collider (EIC). Gluon tomography is mathematically encoded into the gluon Weizs̈acker-Williams (WW) transverse momentum dependent (TMD) distribution which, in light cone gauge, represents the...

Using the colour dipole picture and the colour glass condensate (CGC) framework, we systematically study the diffractive production of two (quark-antiquark) and three (quark, antiquark, and gluon) jets via coherent photon-nucleus interactions at high energy. We focus on the hard scattering regime where at least one of the transverse momentum scales in the problem (the photon virtuality and/or...

Factorization theorems have long been a successful and elegant tool to describe and interpret hadronic structure. The early parton model picture, first developed by Feynman, has now been generalized past the leading power description of inclusive processes like deep inelastic scattering (DIS) to semi-inclusive ones like SIDIS and much more. However, a consistent description of both collinear...

$J/\psi$-pair production at the LHC is currently the most promising tool to probe the unknown *gluon* transverse momentum distributions (TMDs). Data from LHCb at low transverse momenta are already available and more are expected soon from CMS and LHCb. Such data in the collider mode should soon allow one to probe the evolution of the unpolarised-gluon TMDs and to measure, for the first time,...

Quarkonia are very important tools to probe gluon transverse momentum dependent (TMD) distributions at lower energies as compared, for instance, to Higgs production. Among them, the $J/\psi$ meson is one of the most studied, since it frequently decays into lepton pairs, making its detection easier with respect to other quarkonia. Thus, describing observables that involve $J/\psi$ production...

We explore the possibility to use ultra-peripheral proton-lead collisions at the LHC to study inclusive $J/\psi$ photoproduction, namely when a quasi-real photon emitted by the fully stripped lead ion breaks a proton to produce the $J/\psi$. Owing to the extremely large energies of the colliding hadrons circulating in the LHC, the range of accessible $W_{\gamma p}$ largely exceed what has been...