EWS time delay in low energy e C60 elastic scattering

TL;DR

This work addresses the temporal aspects of low-energy elastic $e$-$C_{60}$ scattering by computing Eisenbud-Wigner-Smith (EWS) time delays within a non-relativistic partial-wave framework. It compares two interaction potentials—an annular square well (ASW) and a density functional theory (DFT, LDA) description—both with and without a static polarization potential, enabling a detailed study of how polarization and model choice influence resonant and non-resonant delays. The authors extract resonance parameters via Fano fits and map resonant phase shifts and time delays across partial waves up to $\ell=15$, showing that DFT yields more resonances and longer delays, while polarization lowers resonant energies and can introduce subtle, near-threshold features. The results demonstrate high sensitivity of time delay to the interaction potential, suggesting that precise measurements of $EWS$ time delays in $e$-$C_{60}$ scattering could provide deep insights into fullerene-electron interactions and support potential ultrafast scattering experiments and quantum-memory applications.

Abstract

Time delay in a projectile-target scattering is a fundamental tool in understanding their interactions by probing the temporal domain. The present study focuses on computing and analyzing the Eisenbud-Wigner-Smith (EWS) time delay in low energy elastic e C60 scattering. The investigation is carried out in the framework of a non-relativistic partial wave analysis (PWA) technique. The projectile-target interaction is described in (1) Density Functional Theory (DFT) and (2) Annular Square Well (ASW) static model, and their final results are compared in details. The impact of polarization on resonant and non-resonant time delay is also investigated.

Figures (8)

• Figure 1: (a) ASW and (b) DFT model potentials with and without polarization effects.
• Figure 2: TCS of $e-C_{60}$ elastic scattering using (a) ASW (black) and ASW-P (red); (b) DFT (blue) and DFT-P (magenta). Resonances are labeled with corresponding partial wave numbers. The inset shows magnified TCS in the low-energy region.
• Figure 3: Phase shift (upper panel) and corresponding time delay (lower panel) in the near-zero energy range using model potentials ASW (black) ASW-P(red), DFT (blue) and DFT-P (magenta). Inset shows the magnified view of time delay for $\ell$=1 and 3 partial waves.
• Figure 4: Comparison of $e-C_{60}$ elastic scattering resonant cross-sections calculated using PWA (black) with that from Fano fitting (orange) for ASW (upper panel) and ASW-P (lower panel). Vertical line indicates the resonant energy $E_r$.
• Figure 5: Comparison of $e-C_{60}$ elastic scattering resonant cross-sections calculated using PWA (black) with that from Fano fitting (orange) for DFT (upper panel) and DFT-P (lower panel). Vertical line indicates the resonant energy $E_r$.