Revisiting puffy dark matter with novel insights: partial wave analysis

We present a comprehensive study on the self-interaction cross-section of puffy dark matter (DM) particles, which have a significant intrinsic size compared to their Compton wavelength. For such puffy DM self-interaction cross-section in the resonant and classical regimes, our study demonstrates the significance of the Yukawa potential and the necessity of partial wave analysis: (i) Due to the finite-size effect of puffy DM particles, the new Yukawa potential of puffy DM is found to enlarge the Born-effective regime for the self-interaction cross-section, compared with the point-like DM; (ii) Our partial wave analysis shows that depending on the value of the ratio between R-chi (radius of a puffy DM particle) and 1/m(phi) (force range), the three regimes (Born-effective, resonant and classical) for puffy DM self-interaction cross-section can be very different from the point-like DM; (iii) We find that to solve the small-scale anomalies via self-interacting puffy DM, the Born-effective and the resonant regimes exist for dwarf galaxies, while for the cluster and Milky Way galaxy the non-Born regime is necessary.

Automated summary

We conducted a comprehensive study on the self-interaction cross-section of puffy dark matter particles, taking into account the significant intrinsic size of these particles. Our study highlights the importance of the Yukawa potential and partial wave analysis in understanding this cross-section in the resonant and classical regimes. We found that the finite-size effect of puffy dark matter particles enlarges the Born-effective regime, and the three regimes for the self-interaction cross-section can differ significantly from point-like dark matter, depending on the ratio between the particle radius and the force range.