Probing CP violation in dark scalar decays at the SHiP experiment
Abstract
We investigate CP violation in the decays of a GeV-scale dark scalar boson into mesons, muons and photons. Both scalar and pseudoscalar couplings to the SM fermions are considered to study how the CP structure of the dark scalar boson can be probed through its decays. The scalar and pseudoscalar interactions predominantly induce decays into two-meson and three-meson final states, respectively. We propose the simultaneous observation of these two classes of decay modes as a probe of CP violation in the dark scalar sector. The expected signal rates at the SHiP and FASER2 experiments are evaluated based on the dark scalar production from heavy-meson decays. We find that the ratio of three-meson to two-meson decay events at SHiP has the potential to probe a wide range of the CP-violating parameter space for dark scalar masses around the GeV scale. We also show that the two-muon and di-photon channels can provide complementary information for the CP violation search.
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BibTeX
@misc{aoki2026probing,
title = {{Probing CP violation in dark scalar decays at the SHiP experiment}},
author = {Mayumi Aoki and Takashi Shimomura},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11088},
eprint = {2610.11088},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11088},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Probing CP violation in dark scalar decays at the SHiP experiment
AU - Mayumi Aoki
AU - Takashi Shimomura
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.11088
UR - https://arxiv.org/abs/2610.11088
AB - We investigate CP violation in the decays of a GeV-scale dark scalar boson into mesons, muons and photons. Both scalar and pseudoscalar couplings to the SM fermions are considered to study how the CP structure of the dark scalar boson can be probed through its decays. The scalar and pseudoscalar interactions predominantly induce decays into two-meson and three-meson final states, respectively. We propose the simultaneous observation of these two classes of decay modes as a probe of CP violation in the dark scalar sector. The expected signal rates at the SHiP and FASER2 experiments are evaluated based on the dark scalar production from heavy-meson decays. We find that the ratio of three-meson to two-meson decay events at SHiP has the potential to probe a wide range of the CP-violating parameter space for dark scalar masses around the GeV scale. We also show that the two-muon and di-photon channels can provide complementary information for the CP violation search.
ER -