Sommerfeld enhancement from unstable final-state particles in dark matter annihilation

Fuente: arXiv
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Auteurs principaux: Abe, Tomohiro, Sato, Ryosuke, Yamanaka, Takumu
Format: Preprint
Publié: 2026
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author Abe, Tomohiro
Sato, Ryosuke
Yamanaka, Takumu
author_facet Abe, Tomohiro
Sato, Ryosuke
Yamanaka, Takumu
contents We study the Sommerfeld enhancement of the annihilation cross section of dark matter into heavier unstable particles. In this process, the annihilation products become non-relativistic near the kinematical threshold. If they experience long-range interactions with each other, their wave function is distorted from a plane wave, and the annihilation cross section can be significantly enhanced. When evaluating the Sommerfeld enhancement from the long-range interactions between the annihilation products, the decay of the products needs to be taken into account. We treat this issue by including the decay width in the Schrödinger equations of the two-body wave function of the annihilation products. We find that bound states of the annihilation products with a narrow decay width enhance the annihilation cross section through a resonant effect. At the same time, this formulation automatically includes the annihilation process with off-shell final state particles, which is relevant for a wide decay width. We show that the resonant effect significantly affects the prediction of the dark matter relic abundance.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02647
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Sommerfeld enhancement from unstable final-state particles in dark matter annihilation
Abe, Tomohiro
Sato, Ryosuke
Yamanaka, Takumu
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
We study the Sommerfeld enhancement of the annihilation cross section of dark matter into heavier unstable particles. In this process, the annihilation products become non-relativistic near the kinematical threshold. If they experience long-range interactions with each other, their wave function is distorted from a plane wave, and the annihilation cross section can be significantly enhanced. When evaluating the Sommerfeld enhancement from the long-range interactions between the annihilation products, the decay of the products needs to be taken into account. We treat this issue by including the decay width in the Schrödinger equations of the two-body wave function of the annihilation products. We find that bound states of the annihilation products with a narrow decay width enhance the annihilation cross section through a resonant effect. At the same time, this formulation automatically includes the annihilation process with off-shell final state particles, which is relevant for a wide decay width. We show that the resonant effect significantly affects the prediction of the dark matter relic abundance.
title Sommerfeld enhancement from unstable final-state particles in dark matter annihilation
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2603.02647