Speaker
Description
We present a detailed investigation of the relativistic spatial structure of transverse angular momentum, including both orbital and intrinsic spin, and examine how these quantities are modified by boost effects. Using the quantum phase-space (Wigner) formalism, we begin with three-dimensional spatial distributions of transverse orbital angular momentum, intrinsic spin, and boost in an arbitrary Lorentz frame. By integrating these 3D distributions along the longitudinal direction, we obtain, for the first time, the corresponding 2D spatial distributions of orbital angular momentum, intrinsic spin, total angular momentum, and boost for both spin-0 and spin-1/2 systems. These distributions are analyzed with respect to three physically relevant pivots: the center of mass, the center of energy, and the center of spin. We verify the transverse spin sum rule for all three pivots for spin-1/2 targets. Interestingly, we find that both the transverse total angular momentum and the boost distribution exhibit non-trivial structure even for spin-0 systems, highlighting the dynamical richness of relativistic effects. We further show how the spatial patterns of transverse orbital angular momentum, intrinsic spin, and total angular momentum vary with the target’s momentum. Finally, we also provide the corresponding distributions in the light-front Drell–Yan frame, establishing a clear connection between instant-form and light-front descriptions of transverse angular momentum and boost.
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