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Main Authors: Duan, Kai-Kai, Wang, Xiao, Li, Wen-Hao, Xu, Zhi-Hui, Tsai, Yue-Lin Sming, Fan, Yi-Zhong
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2506.13352
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author Duan, Kai-Kai
Wang, Xiao
Li, Wen-Hao
Xu, Zhi-Hui
Tsai, Yue-Lin Sming
Fan, Yi-Zhong
author_facet Duan, Kai-Kai
Wang, Xiao
Li, Wen-Hao
Xu, Zhi-Hui
Tsai, Yue-Lin Sming
Fan, Yi-Zhong
contents This study examines the impact of solar modulation on the antiproton excess observed by AMS-02, which may indicate dark matter (DM) annihilation. We analyze three solar modulation models: the force-field approximation (FFA), a time-, charge-, and rigidity-dependent FFA, and a three-dimensional numerical simulation based on the Parker transport equation. Based on AMS-02 latest antiproton data (2025), our results show that the significance of the DM signal is sensitive to the chosen modulation model, with a 2$σ$ signal for the FFA (4$σ$ if including data from H, He, C, O, B/C, and B/O) and a reduced significance for more complex models. We also address systematic uncertainties using two methods: the add-in-quadrature method, which assumes uncorrelated uncertainties between energy bins, and the nuisance parameter method, which treats systematic uncertainties as nuisance parameters during the fitting process. Fitted to AMS-02 antiproton data, DM annihilation to the $b\bar{b}$ scenario with three different solar modulation models shows that the add-in-quadrature method causes overfitting, whereas the nuisance parameters approach leads to underfitting. Statistically, the signal region of the FFA model using the add-in-quadrature method is the most reliable. This work highlights the need for refined solar modulation models and a better treatment of uncertainties for a conclusive interpretation of the AMS-02 data.
format Preprint
id arxiv_https___arxiv_org_abs_2506_13352
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scrutinizing the impact of the solar modulation on AMS-02 antiproton excess
Duan, Kai-Kai
Wang, Xiao
Li, Wen-Hao
Xu, Zhi-Hui
Tsai, Yue-Lin Sming
Fan, Yi-Zhong
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
This study examines the impact of solar modulation on the antiproton excess observed by AMS-02, which may indicate dark matter (DM) annihilation. We analyze three solar modulation models: the force-field approximation (FFA), a time-, charge-, and rigidity-dependent FFA, and a three-dimensional numerical simulation based on the Parker transport equation. Based on AMS-02 latest antiproton data (2025), our results show that the significance of the DM signal is sensitive to the chosen modulation model, with a 2$σ$ signal for the FFA (4$σ$ if including data from H, He, C, O, B/C, and B/O) and a reduced significance for more complex models. We also address systematic uncertainties using two methods: the add-in-quadrature method, which assumes uncorrelated uncertainties between energy bins, and the nuisance parameter method, which treats systematic uncertainties as nuisance parameters during the fitting process. Fitted to AMS-02 antiproton data, DM annihilation to the $b\bar{b}$ scenario with three different solar modulation models shows that the add-in-quadrature method causes overfitting, whereas the nuisance parameters approach leads to underfitting. Statistically, the signal region of the FFA model using the add-in-quadrature method is the most reliable. This work highlights the need for refined solar modulation models and a better treatment of uncertainties for a conclusive interpretation of the AMS-02 data.
title Scrutinizing the impact of the solar modulation on AMS-02 antiproton excess
topic Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2506.13352