Transverse single-spin asymmetry for very forward neutral pion production in polarized $p+p$ collisions at $\sqrt{s}=510$ GeV

Abstract

Transverse single-spin asymmetries of very forward neutral pions generated in polarized $p+p$ collisions allow us to understand the production mechanism in terms of perturbative and non-perturbative strong interactions. During 2017 the RHICf Collaboration installed an electromagnetic calorimeter in the zero-degree region of the STAR detector at the Relativistic Heavy Ion Collider (RHIC) and measured neutral pions produced at pseudorapidity larger than 6 in polarized $p$+$p$ collisions at $\sqrt{s}$ = 510 GeV. The large non-zero asymmetries increasing both in longitudinal momentum fraction $x_F$ and transverse momentum $p_T$ have been observed at low transverse momentum $p_T<1$ GeV/$c$ for the first time at this collision energy. The asymmetries show an approximate $x_F$ scaling in the $p_T$ region where non-perturbative processes are expected to dominate. A non-negligible contribution from soft processes may be necessary to explain the nonzero neutral pion asymmetries.

arXiv commentThis paper submitted to PRL is the final result of arXiv:1902.07852

References in corpus (13)

• Fragmentation of Transversely Polarized Quarks Probed in Transverse Momentum Distributions
• QGSJET-II: towards reliable description of very high energy hadronic interactions
• Cross Sections and Transverse Single-Spin Asymmetries in Forward Neutral-Pion Production from Proton Collisions at \sqrt{s} = 200 GeV
• Measuring transversity densities in singly polarized hadron-hadron and lepton-hadron collisions
• The RHIC Zero Degree Calorimeter
• Forward Neutral Pion Transverse Single Spin Asymmetries in p+p Collisions at \sqrt{s}=200 GeV
• Twist-3 Formalism for Single Transverse Spin Asymmetry Reexamined: Semi-Inclusive Deep Inelastic Scattering
• Towards an explanation of transverse single-spin asymmetries in proton-proton collisions: the role of fragmentation in collinear factorization
• Measurements of longitudinal and transverse momentum distributions for neutral pions in the forward-rapidity region with the LHCf detector
• Measurement of zero degree single photon energy spectra for sqrt(s) = 7TeV proton-proton collisions at LHC
• The STAR Vertex Position Detector
• Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV
• Cross Sections and Transverse Single-Spin Asymmetries in Forward Jet Production from Proton Collisions at $\sqrt{s}=500$ GeV

Cited by in corpus (7)

• Measurement of transverse single-spin asymmetries of ${\pi }^0$ and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions
• Transverse momentum dependent forward neutron single spin asymmetries in transversely polarized $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV
• Energy Independence of the Collins Asymmetry in $p^{\uparrow }p$ Collisions
• Probing nucleon spin structure in deep-inelastic scattering, proton-proton collisions and Drell-Yan processes
• Performance of RHICf detector during operation in 2017
• Triple Regge exchange and transverse single-spin asymmetries of the very forward neutral pion production in polarized $p+p$ collisions
• Towards a test of the Born rule in high-energy collisions