Predictions for Sivers single spin asymmetries in one- and two-hadron electroproduction at CLAS12 and EIC

Abstract

The study of the Sivers effect, describing correlations between the transverse polarization of the nucleon and its constituent (unpolarized) parton's transverse momentum, has been the topic of a great deal of experimental, phenomenological and theoretical effort in recent years. Semi-inclusive deep inelastic scattering measurements of the corresponding single spin asymmetries (SSA) at the upcoming CLAS12 experiment at JLab and the proposed Electron-Ion Collider will help to pinpoint the flavor structure and the momentum dependence of the Sivers parton distribution function describing this effect. Here we describe a modified version of the $\mathtt{PYTHIA}$ Monte Carlo event generator that includes the Sivers effect. Then we use it to estimate the size of these SSAs, in the kinematics of these experiments, for both one and two hadron final states of pions and kaons. For this purpose we utilize the existing Sivers parton distribution function (PDF) parametrization extracted from HERMES and COMPASS experiments. Using this modified version of $\mathtt{PYTHIA}$, we also show that the the leading order approximation commonly used in such extractions may provide significantly underestimated values of Sivers PDFs, as in our Monte Carlo simulations the omitted parton showers and non-DIS processes play an important role in these SSAs, for example in the COMPASS kinematics.

18 pages, 27 figures. V2: updated to version published in PRD, two references have been added and some minor changes done to the text

References in corpus (10)

• PYTHIA 6.4 Physics and Manual
• Sivers Effect for Pion and Kaon Production in Semi-Inclusive Deep Inelastic Scattering
• Understanding the large-distance behavior of transverse-momentum-dependent parton densities and the Collins-Soper evolution kernel
• Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised proton
• Evidence for a Transverse Single-Spin Asymmetry in Leptoproduction of pi+pi- Pairs
• SIDIS in the target fragmentation region: polarized and transverse momentum dependent fracture functions
• Calculating Kaon Fragmentation Functions from NJL-Jet Model
• Sivers Effect in Dihadron Semi-Inclusive Deep Inelastic Scattering
• Azimuthal Correlations in the Structure Functions of polarized Dihadron Semi-Inclusive Deep Inelastic Scattering
• Sivers Effect in Dihadron Electroproduction

Cited by in corpus (13)

• Jet-based measurements of Sivers and Collins asymmetries at the future Electron-Ion Collider
• Accessing the Gluon Sivers Function at a future Electron-Ion Collider
• Di-hadron fragmentation and mapping of the nucleon structure
• A journey into the proton structure: Progresses and challenges
• The $g_T(x)$ contribution to single spin asymmetries in SIDIS
• Single-spin asymmetry in dihadron production in SIDIS off the longitudinally polarized nucleon target
• Monte Carlo Implementation of Polarized Hadronization
• Double spin asymmetry in dihadron production in SIDIS off the longitudinally polarized nucleon target
• Spin Orbit Correlations and the Structure of the Nucleon
• Double-spin asymmetry $A_{LT}^{\cos {\varphi }_S}$ in semi-inclusive DIS at CLAS12 and EIC within the collinear framework
• Single spin asymmetry $A_{UL}^{\sin ({\varphi }_h-{\varphi }_R)}$ in dihadron semi-inclusive DIS
• Single spin asymmetry $A_{UL}^{\sin (2{\varphi }_h-2{\varphi }_R)}$ in dihadron semi-inclusive DIS
• The cos${\varphi }_R$ asymmetry of dihadron production in double longitudinally polarized SIDIS