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PandaX’s first attempt to “see” the solar neutrino floor

Background neutrinos can elastically scatter with target nucleus (coherently elastic neutrino-nucleus scattering or CEvNS), producing nuclear recoil signals in a dark matter detector that can mimic dark matter signals. This intrinsic background is the so-called “neutrino floor”, which will ultimately limit the sensitivity of dark matter direct detection. On the other hand, it also provides very interesting physics opportunities to study neutrino interactions. A first search for solar 8B neutrino CEvNS on xenon using PandaX-4T is carried out using the commissioning data set. The energy threshold of this search is further lowered compared to previous search for dark matter, with various techniques utilized to suppress the background that emerges from data with the lowered threshold. A blind analysis is performed on data with an effective exposure of 0.48 tonne-year and no significant excess of events is observed. Among results obtained using neutrino-nucleus coherent scattering, our results give the best constraint on solar 8B neutrino flux. We further provide more stringent limit on cross section between dark matter and nucleon in the mass range from 3 to 10 GeV. The paper has been submitted to arXiv and PRL. You may also find it here.

This new result is released at this year's 23rd International Conference on General Relativity and Gravitation in Beijing on July 5th. You can find the talk at here.