Observation of Beam Spin Asymmetries in the Process $ep\to e{\pi }^{+}{\pi }^{-}X$ with CLAS12

Abstract

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function $e(x)$, which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function $G_1^{\perp }$. A clear sign change is observed around the $\rho$ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark.

arXiv comment6 pages, 5 figures

References in corpus (23)

• The Spin Structure of the Nucleon
• A QCD Analysis of the Mass Structure of the Nucleon
• Parton Fragmentation Functions
• Transverse-momentum-dependent parton distributions up to N${}^3$LL from Drell-Yan data
• Observation of transverse polarization asymmetries of charged pion pairs in e+e- annihilation near sqrt s=10.58 GeV
• Partial-wave analysis of two-hadron fragmentation functions
• Two-hadron semi-inclusive production including subleading twist
• First extraction of Interference Fragmentation Functions from e+e- data
• Evidence for a Transverse Single-Spin Asymmetry in Leptoproduction of pi+pi- Pairs
• Azimuthal asymmetries at CLAS: Extraction of e^a(x) and prediction of A_{UL}
• Interference fragmentation functions in electron-positron annihilation
• The chirally-odd twist-3 distribution e(x)
• Transverse spin effects in hard semi-inclusive collisions
• The twist-three distribution $e^q(x,k_{\perp })$ in a light-front model
• Azimuthal asymmetries in unpolarized SIDIS and Drell-Yan processes: a case study towards TMD factorization at subleading twist
• Production of two hadrons in semi-inclusive Deep Inelatic Scattering
• Dihadron fragmentation functions in the quark-jet model: Longitudinally polarized quarks
• Accessing Quark Helicity through Dihadron Studies
• Beam spin asymmetry in semi-inclusive electroproduction of a hadron pair
• Relating hadronic CP-violation to higher-twist distributions
• Single-spin asymmetry in dihadron production in SIDIS off the longitudinally polarized nucleon target
• Spin Orbit Correlations and the Structure of the Nucleon
• Single spin asymmetry $A_{UL}^{\sin ({\varphi }_h-{\varphi }_R)}$ in dihadron semi-inclusive DIS

Cited by in corpus (11)

• 50 Years of Quantum Chromodynamics
• Precision Studies of QCD in the Low Energy Domain of the EIC
• The Present and Future of QCD
• Presenting Unbinned Differential Cross Section Results
• Strong Interaction Physics at the Luminosity Frontier with 22 GeV Electrons at Jefferson Lab
• Extraction of the higher-twist parton distribution $e(x)$ from CLAS data
• Production of vector mesons in the String+${}^3{P}_0$ model of polarized quark fragmentation
• A journey into the proton structure: Progresses and challenges
• Longitudinal Spin Transfer to $\Lambda$ Hyperons in CLAS12
• Probing nucleon spin structure in deep-inelastic scattering, proton-proton collisions and Drell-Yan processes
• Beam Spin Asymmetries of ${\pi }^{+}{\pi }^0$ Dihadrons from SIDIS at CLAS12