Polarized jet fragmentation functions

Abstract

We develop the theoretical framework needed to study the distribution of hadrons with general polarization inside jets, with and without transverse momentum measured with respect to the standard jet axis. The key development in this paper, referred to as "polarized jet fragmentation functions", opens up new opportunities to study both collinear and transverse momentum dependent (TMD) fragmentation functions. As two examples of the developed framework, we study longitudinally polarized collinear Λ and transversely polarized TMD Λ production inside jets in both pp and ep collisions. We find that both observables have high potential in constraining spin-dependent fragmentation functions with sizeable asymmetries predicted, in particular, at the future Electron-Ion Collider.

Jet-based measurements of Sivers and Collins asymmetries at the future electron-ion collider

“…In this case, the spin-vector s T of the incoming proton correlates with j T , which leads to a sin(φ s − φ h ) modulation usually referred to as the Collins asymmetry for hadron in-jet production. Following the work of [5,9,14,22,23,35,[45][46][47], the relevant cross section can be written as…”

“…For example, Higgs-plus-jet production at the LHC gives access to the gluon TMD PDF [2], while the hadron transversemomentum distribution inside jets probes TMD FFs [3][4][5]. Recently, jet production in deep-inelastic scattering (DIS) regime was proposed as a key channel for TMD studies [6][7][8][9]. Jets produced in polarized protonproton collisions probe the Sivers [10][11][12], transversity and Collins TMDs [13][14][15].…”

Spin asymmetries in electron-jet production at the future electron ion collider

“…In the sense of exclusive jet production, the theoretical advances in the collinear JFFs were first studied [23][24][25][26][27], then later studied in the context of inclusive jet production [28][29][30][31][32][33][34]. Besides longitudinal momentum fraction, one can study the transverse momentum distribution of the hadrons in the jet with respect to the jet axis by including transverse momentum dependence to the JFFs, namely transverse momentum dependent jet fragmentation functions (TMDJFFs) [35][36][37][38], which have close connections with the standard transverse-momentum-dependent fragmentation functions (TMDFFs) [39][40][41].…”

Jet Charge: A Flavor Prism for Spin Asymmetries at the Electron-Ion Collider

“…The advent of the ElC with its high luminosity and polarized beams will unlock the full potential of jets as novel tools for probing nucleon structure. It is thus not a surprise that jet physics at the EIC has become a fast emerging field of research [10][11][12][13][14][15][16][17][18]. While a lot of progress has been made in jet physics at the EIC, flavor separation in jet production and the associated spin asymmetries presents a major challenge and has not been addressed in the literature.…”

“…Within this context, there has now been some recent work on jet fragmentation functions, see Refs. [16,19], where measuring the distribution of hadrons inside jets allows for some amount of flavor separation.…”