Jet Charge with Global Event Shapes: Probing Quark Flavor Dynamics

Abstract

We propose measuring the jet electric charge of jet regions, defined within the framework of global event shapes, as a probe of quark flavor dynamics within the nucleon and the hadronization process. In particular, we consider a measurement of the jet region charge while simultaneously keeping track of the energy flow throughout the event, as characterized by the global event shape. As a concrete example, we focus on the measurement of the 1-Jettiness jet charge ($Q$), the jet charge of the jet region ($J$) defined within the framework of the 1-Jettiness global event shape ($τ_1$) for the Deep Inelastic Scattering (DIS) process, $e^- + p \to e^- + J + X$, with unpolarized or longitudinally polarized protons. The 1-Jettiness distribution, binned according to jet charge, allows for enhanced quark flavor separation of the initial state unpolarized or polarized PDFs. On the other hand, the jet charge distribution binned by 1-Jettiness can serve as a probe of quark flavor dynamics in the final state hadronization process. We derive a factorization theorem for simultaneous measurements of $τ_1$ and $Q$ in the resummation region, $τ_1 \ll P_{J_T}$, where $P_{J_T}$ denotes the transverse momentum of the jet region. The factorization theorem contains a new universal charged jet function, generalizing the standard jet function to include a jet charge measurement. Therefore these universal functions can be extracted from a global analysis of N-jettiness and thrust at $e^+e^-$ colliders. We provide simulation studies to demonstrate the sensitivity of the 1-Jettiness jet charge observable to quark flavor dynamics in nucleon structure and explore the possibility of probing the final state hadronization process. This observable is well-suited for applications with existing HERA data and the future Electron-Ion Collider (EIC).