E. Aprile, J. Aalbers, K. Abe, M. M. Abu Rmeileh, M. Adrover, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, D. Antón Martin, S. R. Armbruster, F. Arneodo, L. Baudis, M. Bazyk, V. Beligotti, L. Bellagamba, R. Biondi, A. Bismark, K. Boese, R. M. Braun, G. Bruni, R. Budnik, C. Cai, C. Capelli, J. M. R. Cardoso, A. P. Cimental Chávez, A. P. Colijn, J. Conrad, J. J. Cuenca-García, V. D’Andrea, L. C. Daniel Garcia, M. P. Decowski, A. Deisting, C. Di Donato, P. Di Gangi, S. Diglio, K. Eitel, S. el Morabit, R. Elleboro, A. Elykov, A. D. Ferella, C. Ferrari, H. Fischer, T. Flehmke, M. Flierman, R. Frankel, D. Fuchs, W. Fulgione, C. Fuselli, F. Gao, R. Giacomobono, F. Girard, R. Glade-Beucke, L. Grandi, J. Grigat, H. Guan, M. Guida, P. Gyorgy, R. Hammann, C. Hils, L. Hoetzsch, N. F. Hood, M. Iacovacci, Y. Itow, J. Jakob, F. Joerg, Y. Kaminaga, M. Kara, S. Kazama, P. Kharbanda, M. Kobayashi, D. Koke, K. Kooshkjalali, A. Kopec, E. Kozlova, H. Landsman, R. F. Lang, L. Levinson, A. Li, H. Li, I. Li, S. Li, S. Liang, Z. Liang, Y.-T. Lin, S. Lindemann, M. Lindner, K. Liu, M. Liu, F. Lombardi, J. A. M. Lopes, G. M. Lucchetti, T. Luce, Y. Ma, C. Macolino, G. C. Madduri, J. Mahlstedt, F. Marignetti, T. Marrodán Undagoitia, K. Martens, J. Masbou, S. Mastroianni, V. Mazza, J. Merz, M. Messina, A. Michel, K. Miuchi, R. Miyata, A. Molinario, S. Moriyama, M. Murra, J. Müller, K. Ni, C. T. Oba Ishikawa, U. Oberlack, K. Otsuzuki, S. Ouahada, B. Paetsch, Y. Pan, Q. Pellegrini, R. Peres, J. Pienaar, M. Pierre, G. Plante, T. R. Pollmann, F. Pompa, A. Prajapati, L. Principe, J. Qin, D. Ramírez García, A. Ravindran, A. Razeto, R. Singh, L. Sanchez, J. M. F. dos Santos, I. Sarnoff, G. Sartorelli, M. T. Schiller, P. Schulte, H. Schulze Eißing, M. Schumann, L. Scotto Lavina, M. Selvi, F. Semeria, F. N. Semler, P. Shagin, S. Shi, H. Simgen, Z. Song, A. Stevens, C. Szyszka, A. Takeda, Y. Takeuchi, P.-L. Tan, D. Thers, G. Trinchero, C. D. Tunnell, K. Valerius, S. Vecchi, S. Vetter, G. Volta, B. von Krosigk, C. Weinheimer, D. Wenz, C. Wittweg, V. H. S. Wu, Y. Xing, D. Xu, Z. Xu, M. Yamashita, J. Yang, L. Yang, J. Ye, M. Yoshida, L. Yuan, G. Zavattini, Y. Zhao, M. Zhong, T. Zhu (XENON Collaboration)
5 min
Abstract
We report a 3.3 $σ$ measurement of coherent elastic neutrino-nucleus scattering from solar $^8$B neutrinos using a 6.77 t$\times$yr exposure from the XENONnT experiment, inferring a solar $^8$B neutrino flux of $(5_{-2}^{+3})\times 10^6\,\mathrm{cm}^{-2}\mathrm{s}^{-1}$, consistent with previous measurements. In the presence of the $^8$B "neutrino fog", we find no evidence for light dark matter, and observe diminishing returns in sensitivity with increasing exposure. A 93% increase in exposure from the previous search improves the median sensitivity to 5 GeV/$c^2$ weakly interacting massive particles-nucleon cross section by 10%. The dataset was also used to measure the weak mixing angle at $\sim$ 0.02 GeV/$c$ momentum transfer and constrain physics beyond the Standard Model.
Sam: Most fakes come from echoes after a big energy hit elsewhere, like stray light or single electrons from a loud gamma ray smash. They check how strong the previous big flash was compared to the wait time; a big prior flash close in time flags a fake. This rule cuts stray rates notably.
Alex: Linking events to earlier big bangs weeds out orphans. Computers help with the rest?
Sam: Yes. They train programs—like referees spotting fakes from replay patterns—to scan signal shapes and timings. These keep most true signals while cutting expected fakes from over 400 to about 15. For leftovers, they use data from rejected events as a template.
Alex: What ties it all together for the final count?
Sam: They sort data into bins across key traits like electron signal size and computer scores. A math fit weighs signal versus backgrounds across data sets. It lands on 17 events as expected, with backgrounds adding just a few more. Tests confirm the match.
Alex: The fog's mapped without bias—mostly by chasing accidentals back to their sources.
Sam: Yes. The fit measures the solar boron-8 neutrino flux directly at 5 million per square centimeter per second, give or take about half that amount. It's consistent with earlier detectors like SNO, confirming sun's core models. This pins down the fog's density.
Alex: Does that directly tighten dark matter limits?
Sam: Precisely. No extra events means upper limits on how strongly light dark matter around 5 GeV could interact with xenon. For standard scattering, the new bounds beat prior XENON results.
Alex: With much more exposure, why only marginal gains?
Sam: The neutrino fog mimics light dark matter recoils perfectly, so extra data improves sensitivity by just 10% at 5 GeV. It also probes tweaks to neutrino behavior and the weak mixing angle at tiny momentum transfers.
Alex: Even if dark matter hides deeper, this maps the floor and tests force rules.
Sam: Exactly. The 3.3 sigma detection is a meaningful step—treated as evidence, not proof, since it leaves some room for flukes. Recent calibrations revised yields downward, but the fit holds.
Alex: What does this mean practically for the field?
Sam: It validates solar models and tests constants like the weak mixing angle at ultra-low energies where few measurements exist. It constrains new neutrino interactions too. Future experiments like LZ will build on this.
Alex: A balanced step: tighter bounds, confirmed sun models, and flags for where physics might bend.
Sam: Exactly—a notable quantification of the neutrino floor that guides future detectors. It strengthens liquid xenon as a multi-purpose tool in astroparticle physics.
Alex: Well put. Thanks for joining ResearchPod.