Transverse $\Lambda$ Polarization in $e^{+}{e}^{-}$ collisions

Abstract

In this paper we study transverse polarization of $\Lambda$ hyperons in single-inclusive leptonic annihilation. We show that when the transverse momentum of the $\Lambda$ baryon is measured with respect to the thrust axis, a transverse momentum dependent (TMD) factorization formalism is required and the polarization is generated by the TMD polarizing fragmentation function (TMD PFF), $D_{1T}^{\perp }$. However, when the transverse momentum of the $\Lambda$ baryon is measured with respect to the momentum of the initial leptons, a collinear twist-3 formalism is required and the polarization is generated by the intrinsic collinear twist-3 fragmentation function $D_T$. Thus while these measurements differ from one another only by a change in the measurement axis, they probe different distribution functions. Recently, Belle measured a significant polarization in single-inclusive $\Lambda$ baryon production as a function of the transverse momentum with respect to the thrust axis. However, this data can in principle be re-analyzed to measure the polarization as a function of the transverse momentum of the $\Lambda$ baryon with respect to the lepton pair. This observable could be the first significant probe of the function, $D_T$. In this paper, we first develop a TMD formalism for $\Lambda$ polarization; we then present a recent twist-3 formalism that was established to describe $\Lambda$ polarization. Using the TMD formalism, we demonstrate that the $\Lambda$ polarization at OPAL and Belle can be described using the twist-2 TMD factorization formalism. Finally, we make a theoretical prediction for this polarization in the collinear twist-3 formalism at Belle.

11 pages, 7 figures

References in corpus (9)

• Parton Fragmentation Functions
• Understanding the large-distance behavior of transverse-momentum-dependent parton densities and the Collins-Soper evolution kernel
• Partonic Pole Matrix Elements for Fragmentation
• Light-cone divergence in twist-3 correlation functions
• A model independent analysis of gluonic pole matrix elements and universality of TMD fragmentation functions
• Measurement of the transverse polarization of $\Lambda$ and $\bar{\Lambda }$ hyperons produced in proton-proton collisions at $\sqrt{s}=7$ TeV using the ATLAS detector
• Factorization for the light-jet mass and hemisphere soft function
• Polarization of Lambda and Anti-Lambda in 920 GeV Fixed-Target Proton-Nucleus Collisions
• Leading and higher twist contributions in semi-inclusive e+e- annihilation at high energies

Cited by in corpus (15)

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• Transverse Lambda production at the future Electron-Ion Collider
• Transverse Momentum Dependent Fragmentation Functions from recent BELLE data
• Several Topics on Transverse Momentum-Dependent Fragmentation Functions
• Probing the longitudinal spin transfer via dihadron polarization correlations in unpolarized $e^{+}{e}^{-}$ and $pp$ collisions
• Transverse $\Lambda$ polarization in $e^{+}{e}^{-}$ processes within a TMD factorization approach and the polarizing fragmentation function
• Inclusive and semi-inclusive production of spin-3/2 hadrons in $e^{+}{e}^{-}$ annihilation
• Spin correlations and Bell nonlocality in $\Lambda \bar{\Lambda }$ pair production from $e^{+}{e}^{-}$ collisions with a thrust cut
• Observation of $\Lambda$ hyperon local polarization in pPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV
• Deep Exclusive Meson Production as a probe to the puzzle of $\Lambda$ hyperon polarization
• Measurement of transverse $\Lambda$ and $\bar{\Lambda }$ hyperon polarization in $p$Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV
• Transverse spin polarization as a novel probe of medium-induced transverse-momentum-broadening effect
• Extracting the $\Lambda$ Polarizing Fragmentation Function from Belle $e^{+}{e}^{-}$ Data Within the TMD Formalism
• Kinematic regions in the $e^{+}{e}^{-}\to hX$ factorized cross section in a $2$-jet topology with thrust
• Measurement of transverse polarization of $\Lambda$ and $\bar{\Lambda }$ hyperons inside jets in $pp$ collisions at $\sqrt{s}=200$ GeV