Journal ArticleSearch for charged excited states of dark matter with KamLAND-ZenAbe, S; Eizuka, M; Futagi, S; Gando, A; Gando, Y; Goto, S; Hachiya, T; Hata, K; Hosokawa, K; Ichimura, K; Ieki, S; Ikeda, H; Inoue, K; Ishidoshiro, K; Kamei, Y; Kawada, N; Kishimoto, Y; Koga, M; Kurasawa, M; Mitsui, T; Miyake, H; Morita, D; Nakahata, T; Nakajima, R; Nakamura, K; Nakamura, R; Nakamura, R; Nakane, J; Ozaki, H; Sakai, T; Shimizu, I; Shirai, J; Shiraishi, K; Shoji, R; Suzuki, A; Takeuchi, A; Tamae, K; Watanabe, H; Watanabe, K; Obara, S; Yoshida, S; Umehara, S; Fushimi, K; Kotera, K; Urano, Y; Ichikawa, A; Berger, BE; Fujikawa, BK; Learned, JG; Maricic, J; Axani, SN; Fu, Z; Smolsky, J; Winslow, LA; Efremenko, Y; Karwowski, HJ; Markoff, DM; Tornow, W; Dell'Oro, S; O'Donnell, T; Detwiler, JA; Enomoto, S; Decowski, MP; Weerman, KM; Grant, C; Li, A; Song, HParticle dark matter could belong to a multiplet that includes an electrically charged state. WIMP dark matter (χ0) accompanied by a negatively charged excited state (χ−) with a small mass difference (e.g. < 20 MeV) can form a bound-state with a nucleus such as xenon. This bound-state formation is rare and the released energy is O(1−10) MeV depending on the nucleus, making large liquid scintillator detectors suitable for detection. We searched for bound-state formation events with xenon in two experimental phases of the KamLAND-Zen experiment, a xenon-doped liquid scintillator detector. No statistically significant events were observed. For a benchmark parameter set of WIMP mass mχ0=1 TeV and mass difference Δm=17 MeV, we set the most stringent upper limits on the recombination cross section times velocity 〈σv〉 and the decay-width of χ− to 9.2×10−30cm3/s and 8.7×10−14 GeV, respectively at 90% confidence level.Elsevier2024-08-0110530373Physics Letters B855C1388460370-2693https://doi.org/10.1016/j.physletb.2024.1388462110720; 2310130National Science Foundation