Search for the Pair Production of Dark Particles $X$ with $K_L^0 \to XX$, $X \to \gamma\gamma$

C. Lin; J. K. Ahn; J. M. Choi; M. S. Farrington; M. Gonzalez; N. Grethen; Y. B. Hsiung; T. Inagaki; I. Kamiji; E. J. Kim; J. L. Kim; H. M. Kim; K. Kawata; A. Kitagawa; T. K. Komatsubara; K. Kotera; S. K. Lee; J. W. Lee; G. Y. Lim; Y. Luo; T. Matsumura; K. Nakagiri; H. Nanjo; T. Nomura; K. Ono; J. C. Redeker; T. Sato; V. Sasse; T. Shibata; N. Shimizu; T. Shinkawa; S. Shinohara; K. Shiomi; R. Shiraishi; S. Suzuki; Y. Tajima; Y. -C. Tung; Y. W. Wah; H. Watanabe; T. Wu; T. Yamanaka; H. Y. Yoshida

doi:10.1103/physrevlett.130.111801

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arXiv · 2209.11019

Search for the Pair Production of Dark Particles $X$ with $K_L^0 \to XX$, $X \to \gamma\gamma$

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Abstract

We present the first search for the pair production of dark particles $X$ via $K_L^0\to XX$ with $X$ decaying into two photons using the data collected by the KOTO experiment. No signal was observed in the mass range of 40 - 110 MeV/c$^2$ and 210 - 240 MeV/c$^2$. This sets upper limits on the branching fractions as $\mathcal{B}(K_L^0 \to XX)$ $<$ (1-4) $\times$ 10$^{-7}$ and $\mathcal{B}(K_L^0 \to XX)$ $<$ (1-2) $\times$ 10$^{-6}$ at the 90% confidence level for the two mass regions, respectively.

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C. Lin, J. K. Ahn, J. M. Choi, M. S. Farrington, M. Gonzalez, N. Grethen, Y. B. Hsiung, T. Inagaki, I. Kamiji, E. J. Kim, J. L. Kim, H. M. Kim, K. Kawata, A. Kitagawa, T. K. Komatsubara, K. Kotera, S. K. Lee, J. W. Lee, G. Y. Lim, Y. Luo, T. Matsumura, K. Nakagiri, H. Nanjo, T. Nomura, K. Ono, J. C. Redeker, T. Sato, V. Sasse, T. Shibata, N. Shimizu, T. Shinkawa, S. Shinohara, K. Shiomi, R. Shiraishi, S. Suzuki, Y. Tajima, Y. -C. Tung, Y. W. Wah, H. Watanabe, T. Wu, T. Yamanaka, H. Y. Yoshida. 2022-09-22. Search for the Pair Production of Dark Particles $X$ with $K_L^0 \to XX$, $X \to \gamma\gamma$. https://doi.org/10.1103/physrevlett.130.111801

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