Transverse Lambda production at the future Electron-Ion Collider

Abstract

We provide a comprehensive overview of transversely polarized Λ production at the future Electron-Ion Collider (EIC). In particular, we study both spontaneous transverse Λ polarization as well as the transverse spin transfer within the Transverse Momentum Dependent (TMD) factorization region. To describe spontaneous Λ polarization, we consider the contribution from the TMD Polarizing Fragmentation Function (TMD PFF). Similarly, we study the contribution of the transverse spin transfer originating from the transversity TMD fragmentation function (TMD FF). We provide projections for the statistical uncertainties in the corresponding spin observables at the future EIC. Using these statistical uncertainties, we characterize the role that the future EIC will play in constraining these distributions. We perform an impact study in the semi-inclusive deep inelastic scattering process for spontaneous Λ polarization with a proton beam. We find that the projected experimental data leads to a significant decrease in the uncertainties for the u and sea TMD PFFs. Furthermore, to access the impact of the EIC on the transversity TMD FF, we perform the first extraction of the transversity TMD FF from the recent COMPASS data. We compare the statistical uncertainties of the future EIC with the theoretical uncertainties from our extraction and find that the EIC could have a significant role in constraining this distribution. Finally, we also provide projections for both spontaneous Λ polarization as well as the transverse spin transfer inside the jets in back-to-back electron-jet production at the EIC.

Snowmass 2021 White Paper: Electron Ion Collider for High Energy Physics

“…The authors of Ref. [357] provided projections for the statistical uncertainties in the corresponding spin observables at the future EIC. In particular, they studied the transverse polarization of Λ hyperons inside the jet produced in the scattering of an electron with either an unpolarized or transversely polarized proton beam.…”

Opportunities for precision QCD physics in hadronization at Belle II -- a snowmass whitepaper

“…One example is the observation of large transverse polarizations in Λ production with unpolarized beams [89,90], a phenomenon that is still not completely understood and that has been one of the motivating factors of a large program of spin structure measurements at several facilities over the last few decades. Consequently, the first measurement by Belle [91] prompted strong theoretical activity [92][93][94][95][96][97][98][99] it will also be the base for a hyperon program at the EIC [100].…”

Longitudinal and transverse polarizations of $Λ$ hyperon in unpolarized SIDIS and $e^+e^-$ annihilation

“…Recently, Belle collaboration has measured the transverse polarization of Λ hyperons produced in e + e − annihilation [26] and has inspired immediate parameterizations [27][28][29] and model calculations [30] of the D ⊥Λ 1T q (z Λ , p T ). Efforts have also been made towards predicting the transverse polarization of Λ hyperon in SIDIS [31][32][33][34]. We note in particular that the parameterization in [29] emphasizes on the isospin symmetry while those in [27,28] include quite significant isospin symmetry violations.…”