The 24th International Spin Symposium

Session

Nucleon Helicity Structure

helicity

19 Oct 2021, 18:50

Room 501 (Kunibiki Messe)

Conveners

Nucleon Helicity Structure: Chair: Jinlong Zhang

• Itaru Nakagawa (RIKEN)
• Maria Zurek (Argonne National Laboratory)

Nucleon Helicity Structure: Chair: Jinlong Zhang

• Maria Zurek (Argonne National Laboratory)
• Itaru Nakagawa (RIKEN)

Nucleon Helicity Structure: Chair: Maria Żurek (ANL)

• There are no conveners in this block

Nucleon Helicity Structure: Chair: Maria Żurek (ANL)

• There are no conveners in this block

102. Useful relations and sum rules for PDFs and multiparton distribution functions of spin-1 hadrons

Qin-Tao Song (Zhengzhou University)

19/10/2021, 18:50

Nucleon Helicity Structure

Parallel Session Presentation

Sum rules for structure functions and their twist-2 relations have important roles in constraining their magnitudes and $x$ dependencies and in studying higher-twist effects. The Wandzura-Wilczek (WW) relation and the Burkhardt-Cottingham (BC) sum rule are such examples for the polarized structure functions $g_1$ and $g_2$. Recently, new twist-3 and twist-4 parton distribution functions were...

54. Helicity quasi-PDFs in a large Nc nucleon

Hyeon-Dong Son (Ruhr-University Bochum)

19/10/2021, 19:15

Nucleon Helicity Structure

Parallel Session Presentation

We discuss the properties of the helicity quark quasi-distributions in the large Nc limit. Within the framework of the chiral quark-soliton model, we review the properties of the quasi-PDFs such as the sum rules and the positivity. Numerical results for quark and antiquark isovector helicity distributions are presented. Significant antiquark flavor asymmetry is observed in a wide range of...

98. Measurement of the anti-quark flavor asymmetry in the proton at FNAL-SeaQuest

Kenichi Nakano (University of Virginia)

20/10/2021, 11:15

Nucleon Helicity Structure

Parallel Session keynote talk (by invitation only)

The flavor asymmetry of the unpolarized distributions of light anti-quarks (i.e. $\overline{u}(x)$ and $\overline{d}(x)$) in the proton was observed by several deep-inelastic muon scattering experiments. The ratio $\overline{d}(x)/\overline{u}(x)$ was measured by Drell-Yan experiments NA51 at CERN and E866 at Fermilab and a large asymmetry was reported.

The mechanism of this asymmetry has been studied via...

43. Measurement of longitudinal spin transfer of the $\mathrm{\Lambda }(\overline{\mathrm{\Lambda }})$ hyperon in longitudinally polarized $\mathrm{p}$$+$$\mathrm{p}$ collisions at $\sqrt{s}=200$ $\mathrm{G}\mathrm{e}\mathrm{V}$ at RHIC-STAR

Yi Yu (Shandong University)

20/10/2021, 11:45

Nucleon Helicity Structure

Parallel Session Presentation

Since the first surprising results on the spin structure of the proton by the EMC experiment in the late 1980s, much progress has been made in understanding the origin of the proton spin. However, the sea quark contribution to the proton spin, for example, the helicity distributions of the strange quark (anti-quark), $s(\overline{s})$, is still not well constrained by experimental data. Since the...

83. Studies of Neutral Current Neutrino-Nucleon Scattering with the MicroBooNE Detector

Lu Ren (New Mexico State University)

20/10/2021, 12:05

Nucleon Helicity Structure

Parallel Session Presentation

The MicroBooNE experiment is an 85 ton active volume liquid-argon time projection chamber (LArTPC) located in the Booster Neutrino Beamline at Fermilab. The excellent calorimetric and spatial resolution of the LArTPC allows us to identify isolated proton tracks with lengths as short as 2 cm, which is equivalent to proton kinetic energy T = 50 MeV. We report the progress towards the first...

88. Collinear twist-3 approach to hyperon polarization in SIDIS

Kazuki Takada (Niigata University)

20/10/2021, 12:25

Nucleon Helicity Structure

Parallel Session Presentation

We discuss the production of transversely polarized hyperons in semi-inclusive deep inelastic scattering in the framework of the collinear twist-3 factorization. In this framework, the twist-3 cross section consists of three contributions depending on the origins for the polarizations: (i) Twist-3 distribution in the initial proton combined with the twist-2 transversity fragmentation function...

91. Small-x Helicity Evolution and the Proton Spin Puzzle

Dr Daniel Pitonyak

22/10/2021, 07:00

Nucleon Helicity Structure

Parallel Session keynote talk (by invitation only)

We report on the first phenomenological analysis of the world polarized deep-inelastic scattering (DIS) data incorporating small-x helicity (Kovchegov-Pitonyak-Sievert) evolution. This framework allows for one to predict the behavior of helicity parton distribution functions (PDFs) down to very low x. Consequently, one can control the uncertainties in these functions beyond the measured...

75. First Extraction of Polarized Sea Asymmetry from Weak Boson Production in Proton-Proton Collisions

Christopher Cocuzza (Temple University)

22/10/2021, 07:30

Nucleon Helicity Structure

Parallel Session Presentation

We present the first global QCD analysis of helicity parton distribution functions (PDFs) to include the latest polarized $W$-lepton production data from the STAR collaboration at the Relativistic Heavy-Ion Collider. This data allows the first extraction of a nonzero helicity light quark sea asymmetry within a global QCD analysis. By performing a simultaneous extraction of the unpolarized...

190. J/psi spin asymmetry measurements in p+p collisions at 200 and 510 GeV by the PHENIX experiment at RHIC

alexandre lebedev (Iowa State University)

22/10/2021, 07:50

Nucleon Helicity Structure

Parallel Session Presentation

Studies of heavy quark bound states, like J/psi meson, provide a useful tool to investigate QCD properties. Many general features of J/psi production, such as cross-sections and transverse momentum distributions are well described by many existing models. In order to differentiate between various theoretical models one has to study J/psi production in more details. One of the observables which...

149. The role of the chiral anomaly in polarized deeply inelastic scattering: Topological screening and emergent axion-like dynamics

Dr Andrey Tarasov (The Ohio State University)

22/10/2021, 08:40

Nucleon Helicity Structure

Parallel Session Presentation

I’ll discuss the role of the chiral anomaly in deep inelastic scattering (DIS) of electrons off polarized protons employing a worldline formalism, which is a powerful framework for the computation of perturbative multi-leg Feynman amplitudes. I’ll demonstrate how the triangle anomaly appears at high energies in the DIS box diagram for the polarized structure function $g_1(x_B,Q^2)$ in both the...

113. Measurement of Direct Photon Cross Section and Double Helicity Asymmetry at $\sqrt{s}$ = 510 GeV in $\overrightarrow{p}+\overrightarrow{p}$ Collisions at PHENIX

Mr Zhongling Ji (Stony Brook University)

22/10/2021, 09:10

Nucleon Helicity Structure

Parallel Session Presentation

The proton spin decomposition provides key information about the structure of the nucleons. Since late 1980s, experiments showed that the quark spin contributes only $\sim$30\% to the proton spin, with remaining part coming from gluon spin as well as quark and gluon orbital angular momentum. While the quark spin contribution was better constrained by polarized deep inelastic scattering (DIS),...

142. Recent Longitudinal Spin Results with Charged Pions and Jets at PHENIX

Dr Ross Corliss (Stony Brook University)

22/10/2021, 09:30

Nucleon Helicity Structure

Parallel Session Presentation

Operated at the Relativistic Heavy Ion Collider at Brookhaven until beginning its recent upgrade into sPHENIX, the PHENIX experiment has collected a wealth of data from polarized proton collisions. Analysis of these data sets continues to offer insight into the spin structure of the proton. In particular, RHIC's polarized proton-proton data help constrain polarized PDFs in the proton, and...

99. Constraining the Polarized Gluon Distribution Function of the Proton with Recent STAR Measurements

Nick Lukow (Temple University)

22/10/2021, 09:50

Nucleon Helicity Structure

Parallel Session Presentation

The contribution of the gluon spin to the spin of the proton is being studied through the use of the unique capability of the Relativistic Heavy Ion Collider (RHIC) to collide longitudinally polarized protons at $\sqrt{s}=200$GeV and $\sqrt{s}=510$GeV. The kinematic coverage of the Solenoidal Tracker At RHIC (STAR) allows access to gluons through quark-gluon and gluon-gluon scattering...

55. Illuminating the nucleon spin

Miguel Echevarria (Universidad de Alcalá)

Nucleon Helicity Structure

Parallel Session keynote talk (by invitation only)

I will discuss the extension of the nucleon spin sum rule to QCDxQED. I will present the QED corrections to the evolution of the quark and gluon helicity and orbital-angular-momentum (OAM) distributions, which are calculated for the first time, and the necessary inclusion of photon and lepton helicity and OAM distributions.