セミナー情報

• 日時: 4月24日（金）
• 講師: 山中 拓夢氏(大阪大学)
• 題目: Sommerfeld Enhancement from Unstable Final-state Particles in Dark Matter Annihilation

概要

We study the final-state Sommerfeld enhancement (SE) in dark matter (DM) annihilation into heavier unstable particles, a process relevant to forbidden DM scenarios. If the annihilation products interact via long-range forces, their wave function is significantly distorted from a plane wave as they become non-relativistic near the kinematical threshold. This leads to a large enhancement of the annihilation cross section.

Unlike the conventional formulation of the SE from initial DM particles, the instability of the annihilation products must be taken into account. We formulate this effect by including the decay width of the annihilation products into the Schrödinger equation for the two-body wave function. We show that bound states of the annihilation products resonantly enhance the cross section if their decay width is narrow, and that off-shell contributions are automatically included within this framework. We also demonstrate that this resonant enhancement has a significant impact on the predicted DM relic abundance.