Conveners
3-dimensional structure of nucleon - TMD
- Ting Lin (Shandong University)
- Yuxiang Zhao (University of Science and Technology of China (USTC))
3-dimensional structure of nucleon - TMD
- Alessandro Bacchetta (University of Pavia and INFN)
- Dingyu Shao (Fudan University)
3-dimensional structure of nucleon - TMD: 2
- Valentin Moos (NYCU)
- Shu-yi Wei (Shandong University)
3-dimensional structure of nucleon - TMD: 1
- Zhihong Ye (Tsinghua University)
- Yiyu Zhou (Department of Physics, University of Turin, via Pietro Giuria 1, I-10125 Torino, Italy)
Description
Conveners: Christopher Dilks, Andrea Signori, Ting Lin
The Solenoidal Large Intensity Device (SoLID) is an advanced spectrometer under development in Hall A at Jefferson Lab. Designed for high-luminosity operation (10³⁷–10³⁹ cm⁻²s⁻¹) with both polarized (NH3 and 3He) and unpolarized hydrogen and deuterium targets, SoLID features large acceptance and full azimuthal coverage. It will fully exploit the capabilities of the 12 GeV CEBAF upgrade and is...
Abstract: Fragmentation Function (FF) plays a crucial role in describing the hadronization process. We report the measurements of normalized differential cross sections of inclusive pi0 and Ks production as a function of hadron momentum at six energy points with q^2 transfer from 5 to 13 GeV^2 at BESIII. The results with a relative hadron energy coverage from 0.1 to 0.9 significantly deviate...
For the last two decades, the PHENIX collaboration at Brookhaven National Laboratory has explored nuclear spin physics by leveraging the Relativistic Heavy Ion Collider’s unique ability to collide transversely or longitudinally polarized protons. Eta meson production is a particularly practical channel at PHENIX as their detection is possible through diphoton decays in both the central and...
In proton-proton ($pp$) collisions involving a transversely polarized proton beam and an unpolarized proton beam, a left-right or azimuthal asymmetry is observed in the distribution of final-state scattered particles. The experimentally measurable quantity is known as the Transverse Single Spin Asymmetry ($A_N$). This asymmetry arises from fundamental Transverse Momentum Dependent (TMD)...
This talk will present recent results on the determination of transverse momentum distributions by the MAP collaboration, with a particular emphasis on the flavor dependence of unpolarized TMDs, on the helicity TMD, and on machine-learning methods."
After the conceptual improvements to transverse momentum dependent (TMD) extractions of a flavour dependent ansatz as well as a more robust propagation of uncertainties onto the resulting TMD functions in ART23, the following work ART25 is a state of the art determination of the unpolarised TMD parton distribution functions and -fragmentation functions such as the Collins-Soper kernel via a...
In this talk, I will present the first extraction of TMD helicity distributions, by analyzing double spin asymmetry data from SIDIS.
We present the global analysis of Sivers functions, worm-gear distribution functions, transversity distribution functions, and Collins fragmentation functions within the transverse momentum dependent factorization. This analysis encompasses the latest data from SIDIS, DY, and W±/Z-boson production processes. In addition, based on a combined analysis of world data and simulated data, we...
In this work, we investigate the nuclear modification effects in transverse momentum dependent
(TMD) observables by implementing a nuclear covariance matrix in the treatment of theoretical uncertainties. Global QCD analysis is performed with the aforementioned nuclear covariance matrix to verify its equivalence with the traditional approach of including a nuclear correction parameter. The...
The polarized transverse-mementum-dependent fragmentation function (TMD FF) $D_{1T}^\perp$ have attracted lots of attention from both experiment and theory communities. Starting from a isospin symmetric parametrization for $D_{1T}^\perp$, we have studied transverse polarizations of $\Lambda$ in various collisions. Recently we focus on nuclear collisions and study the QGP medium effects via QCD...
We present an analysis of lepton-jet azimuthal decorrelation in deep-inelastic scattering (DIS) at next-to-next-to-next-to-leading logarithmic (N$^{3}$LL) accuracy, combined with fixed-order corrections at $\mathcal{O}(\alpha_s^2)$. In this study, jets are defined in the lab frame using the anti-$k_T$ clustering algorithm and the winner-take-all recombination scheme. The N$^{3}$LL resummation...
We present two complementary advances toward precision QCD predictions for multi-jet processes at the LHC, both based on observables constructed with the Winner-Take-All (WTA) recombination scheme. First, we develop two generalizations of the transverse-momentum slicing variable $q_T$ applicable to jet final states, enabling a slicing approach for processes like $pp \to 2$ jets. A proof of...
We propose a novel strategy to systematically isolate the nucleon’s intrinsic non-perturbative three-dimensional structure by employing 0-jettiness to suppress initial-state radiation in transverse momentum-dependent (TMD) observables. Applying this method to transverse single spin asymme tries (SSAs) in W$^\pm$ and Z$^0$ boson production at RHIC, we demonstrate a substantial enhancement of...
we explore the Bjorken $x$ weighted EEC in DIS from the TFR to CFR. In both regions, a factorization theorem can be derived with SCET, based on which the logarithms can be resummed to all orders in $\alpha_s$. The singular distributions can be derived from the factorized formula, which are compared against the full fixed-order QCD calculations up to NLO. Additionally, we present the...
In this work, we introduce a new jet observable, the one-point energy correlators (EC), designed to characterize the in-jet energy flow distribution by measuring energy deposition at a specific angle relative to the jet axis. Building upon the transverse momentum dependent physics, we aim for the EC to provide novel insights into jet substructure and offer a new approach to study TMD physics,...
We propose a novel method to probe the Collins effect, a key signature of the nucleon's 3D structure, using an intra-jet energy correlator. This new observable, based on the energy-weighted azimuthal distribution of hadrons within a jet, can be measured in transversely polarized proton-proton collisions at RHIC. The resulting $\sin(\phi_h - \phi_S)$ single-spin asymmetry provides a direct...
We initiate a systematic study of fragmentation energy correlators (FECs), which generalize traditional fragmentation functions and encode non-perturbative information about transverse dynamics in parton fragmentation processes.
We define boost-invariant, non-perturbative FECs and derive a corresponding collinear factorization formula. A spin decomposition of the FECs is carried out,...
The Energy-Energy Correlators (EEC), initially developed in $e^+e^-$ collisions, provide a powerful method for probing the angular structure of energy flows within jets. In hadronic collisions with transverse polarization, the polarized EEC (pEEC) offers unique sensitivities to parton spin-orbit correlations and spin-dependent transverse-momentum-dependent (TMD) effects. In this presentation,...
In the recent years, it has been realized that deep-inelastic scattering with polarization control could provide a variety of spin and azimuthal angle dependent observables sensitive to the quark-gluon interactions. New parton distributions and fragmentation functions have been introduced to describe the rich complexity of the hadron structure and move towards a multi-dimensional imaging of...
SpinQuest at Fermilab is a fixed-target experiment to primarily measure the Drell-Yan process using transversely polarized NH$_3$ and ND$_3$ targets and unpolarized 120-GeV proton beam. In the Drell-Yan process, a quark in one scattering hadron and an anti-quark in the other hadron annihilate into a virtual photon and then decay into a muon (lepton) pair. The angular distribution of...
Jet transverse single spin asymmetries, $A_N$, are only sensitive to the
initial state effects as final state effects are not present. They are
therefore an excellent tool to single out the quark-gluon and tri-gluon
correlation functions that are the higher-twist equivalents to the
transverse momentum moments of the Sivers functions for quarks and
gluons. sPHENIX has taken transversely...
We investigate semi-inclusive deep inelastic scattering (SIDIS) off a tensor-polarized spin-1 target, focusing on the production of an unpolarized hadron. We derive a comprehensive differential cross-section expression, characterized by 23 structure functions, which depend on the target spin states and the azimuthal distribution of the final-state hadron.
Within the TMD factorization...
We investigate the Sivers asymmetry in the production of vector mesons, specifically $\rho^0$ and $K^*$, in SIDIS processes in the TMD factorization framework. By employing the Sivers function extracted from pion and kaon production data, we calculate the transverse single-spin asymmetry for $\rho^0$ production and compare it with recent COMPASS measurements. Our results align well with the...
Transverse single spin asymmetries (TSSAs, denoted AN ) in transversely
polarized p↑ + p collisions provide critical insights into the proton’s spin structure, yet their unexpectedly large magnitudes at forward rapidities remain a
puzzle. Observed across experiments, including those at RHIC, these asymmetries have yet to be fully explained by theoretical models, such as those based...
Direct photon single spin asymmetries, $A_N$, have the advantage that they
are not sensitive to final state effects and that the hard scattering
process is predominantly quark-gluon scattering at RHIC energies.
Therefore, direct photons provide a clean probe to study the quark-gluon
and tri-gluon correlations in single spin asymmetries with particularly
the latter hardly constrained at...
The transverse single-spin asymmetry ($A_{\mathrm{N}}$) serves as a crucial probe for understanding the mechanisms of particle production in polarized high energy particle collisions as well as the internal dynamics of quarks and gluons within a polarized nucleon. The RHICf collaboration measured a non-zero transverse single-spin asymmetry ($A_{\mathrm{N}}$) for very forward ($\eta > 6$)...
Neutral mesons transverse single spin asymmetries, $A_N$, provide insights
into the spin-orbit correlations inside the nucleon via higher twist
correlation functions. As forward rapidities they are known to be very
large while at central rapidities vanishing asymmetries have been
measured. The sPHENIX experiment with electromagnetic calorimetry over a
rapidity range from -1.1 to 1.1 will...
We investigate $\Lambda$ production in semi-inclusive deep inelastic scattering using a polarized lepton beam and find that the spin transfer is significantly suppressed by target fragmentation. As further demonstrated by a model estimation, experimental data can be well described once the target fragmentation is taken into account. Our findings suggest that, at the medium-energy scales of...
Jets produced in association with a ${Z^0}$ or ${W^\pm}$ boson in hadronic collisions are naturally polarized due to the parity violation of weak interaction, making these processes ideal for extracting information about the longitudinal spin transfer $G_{1L}$, and for studying the phenomenon of polarized jet quenching. In this work, we compute the polarization of $\Lambda$ hyperons in $pp$...
The study of the Collins asymmetry in $p^{\uparrow}p$ collisions provides a crucial experimental probe for quark transversities and polarized transverse-momentum-dependent (TMD) fragmentation functions.
In this talk, we present high-precision measurements of the Collins asymmetry for $\pi^{\pm}$ within jets from transversely polarized ${p^{\uparrow}p}$ collisions at $\sqrt{s}$ = 510 GeV by...
According to current understanding, the QCD vacuum contains a condensate of quark-antiquark pairs: $u\bar{u}$, $d\bar{d}$, and $s\bar{s}$. Due to the vacuum’s quantum numbers, $J^{PC} = 0^{++}$, these pairs are expected to appear as maximally entangled spin-triplet states with aligned spins. A recent proposal suggests that the $s\bar{s}$ pairs in the quark condensate may be experimentally...
We present a lattice QCD calculation of the Collins-Soper kernel, which governs the rapidity evolution of transverse-momentum-dependent (TMD) distributions, using Large Momentum Effective Theory (LaMET). Quasi-TMD wave functions are computed with three meson momenta on CLQCD configurations (multiple lattice spacings) employing clover quarks and varied hadronic states. HYP smearing is applied...
The fragmentation process has been proposed as a possible origin of the transverse $\Lambda$ polarization, described by polarizing fragmentation functions (pFFs). In $pp$ collisions, this mechanism can be studied by measuring the $\Lambda$ polarization within jets. We present the first measurement of the transverse polarization of $\Lambda$/$\overline{\Lambda}$ hyperons relative to the jet...
We study the pion's leading and sub-leading twist PDFs, i.e., f(x) and e(x), using a newly developed technique within Dyson-Schwinger equations approach. We will show how the complexities brought by high Fock-state components, zero mode issue and dynamical chiral symmetry breaking can be handled in a consistent and symmetry-preserving framework that connects continuum QCD dynamics to...
The transverse polarization of $\Lambda$ hyperons in unpolarized hadron--hadron reactions, first observed decades ago, is still not fully understood. The polarizing fragmentation functions, which are expected to contribute to the $\Lambda$ polarization, can be investigated by measuring the $\Lambda/\bar{\Lambda}$ transverse polarization inside jets in $pp$ collisions. In this contribution, we...
In 2024, the sPHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory completed its first ever transversely polarized proton data taking, collecting approximately 100 billion unbiased collisions. The sPHENIX tracking system, composed of a vertex detector with monolithic active pixel sensor technology, an intermediate silicon strip detector, and a compact time...
