English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Experimental observations of strikingly large transverse single-spinasymmetries (TSSAs) opened a window into quark and gluon dynamics present inhadronic collisions, revealing large spin-momentum correlations within nucleonsand in the process of forming hadrons. Though originally measured in lowerenergy fixed target experiments, they have been found to persist in collisionswith momentum transfer well into the perturbative regime of quantumchromodynamics (QCD) and yet their origin remains poorly understood. TSSAmeasurements have allowed for the development of both transverse momentumdependent and collinear twist-3 descriptions of nonperturbative spin-momentumcorrelations for both initial- and final-state effects. Results are presentedfor the TSSAs of direct photons, neutral pions, and eta mesons in thepseudorapidity range $|\eta|<0.35$ from $p^\uparrow+p$ collisions with$\sqrt{s} = 200$ GeV at PHENIX. As hadrons, $\pi^0$ and $\eta$ mesons aresensitive to both initial- and final-state effects. At midrapidity, $\pi^0$ and$\eta$ measurements are sensitive to the dynamics of gluons along with a mix ofquark flavors. These results are a factor of three increase in statisticalprecision and extend to higher transverse momentum when compared with previousPHENIX measurements in this kinematic region. Because direct photon productiondoes not include hadronization, the direct photon TSSA is only sensitive tospin-momentum correlations in the proton. The kinematics of this result inparticular make the direct photon TSSA a clean probe of gluon dynamics in thetransversely polarized proton. All three of these asymmetries will helpconstrain the twist-3 trigluon collinear correlation function as well as thegluon Sivers function, improving our knowledge of spin-dependent gluon dynamicsin QCD.

Transverse Single-Spin Asymmetries of Midrapidity Direct Photons,  Neutral Pions, and Eta Mesons in 200 GeV Polarized Proton-Proton Collisions  at PHENIX