Search for Sub-GeV Axion-Like Particles at EBES Pilot Run Using 4 GeV Positron Beam at KEK LINAC
Abstract
We report the results of a search for sub-GeV axion-like particles (ALPs) using pilot run data from the Electron Beam-dump Experiment at KEK LINAC Switching Yard 3 (EBES). The data were collected in December 2023 with a 4 GeV positron beam and correspond to 5.7×1013 positrons on target. In the pilot run setup, a tungsten beam dump and a single PbO calorimeter were used. We consider ALP production via the Primakoff process induced by bremsstrahlung photons in the beam dump, followed by the decay a→γγ. The background was estimated with a data-driven method, and a signal region was defined such that the expected background yield is below 0.1 events. No events were observed after unblinding. Upper limits at the 90% confidence level were derived in the ALP mass-coupling plane, extending the experimental coverage into a region of parameter space not explored by previous searches.
Versions
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BibTeX
@misc{fusayasu2026search,
title = {{Search for Sub-GeV Axion-Like Particles at EBES Pilot Run Using 4 GeV Positron Beam at KEK LINAC}},
author = {Takahiro Fusayasu and Tomoya Iizawa and Fumihito Ikeda and Akimasa Ishikawa and Masako Iwasaki and Hiroshi Iwase and Takahiro Kawahara and Aoi Masaki and Fusashi Miyahara and Yu Morikawa and Yuichi Okayasu and Toshiyuki Ono and Hidetoshi Otono and Yasuhito Sakaki and Takumi Seino and Yuta Shimasaki and Taikan Suehara and Yosuke Takubo and Shusaku Tsumura and Kosuke Uemura and Yifu Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.07108},
eprint = {2605.07108},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.07108},
}
RIS
TY - UNPB
TI - Search for Sub-GeV Axion-Like Particles at EBES Pilot Run Using 4 GeV Positron Beam at KEK LINAC
AU - Takahiro Fusayasu
AU - Tomoya Iizawa
AU - Fumihito Ikeda
AU - Akimasa Ishikawa
AU - Masako Iwasaki
AU - Hiroshi Iwase
AU - Takahiro Kawahara
AU - Aoi Masaki
AU - Fusashi Miyahara
AU - Yu Morikawa
AU - Yuichi Okayasu
AU - Toshiyuki Ono
AU - Hidetoshi Otono
AU - Yasuhito Sakaki
AU - Takumi Seino
AU - Yuta Shimasaki
AU - Taikan Suehara
AU - Yosuke Takubo
AU - Shusaku Tsumura
AU - Kosuke Uemura
AU - Yifu Zhang
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2605.07108
UR - https://arxiv.org/abs/2605.07108
AB - We report the results of a search for sub-GeV axion-like particles (ALPs) using pilot run data from the Electron Beam-dump Experiment at KEK LINAC Switching Yard 3 (EBES). The data were collected in December 2023 with a 4 GeV positron beam and correspond to 5.7×10^13 positrons on target. In the pilot run setup, a tungsten beam dump and a single PbO calorimeter were used. We consider ALP production via the Primakoff process induced by bremsstrahlung photons in the beam dump, followed by the decay a→γγ. The background was estimated with a data-driven method, and a signal region was defined such that the expected background yield is below 0.1 events. No events were observed after unblinding. Upper limits at the 90% confidence level were derived in the ALP mass-coupling plane, extending the experimental coverage into a region of parameter space not explored by previous searches.
ER -