TY - JOUR
T1 - Dark matter interpretation of excesses in multiple direct detection experiments
AU - Kurinsky, Noah
AU - Baxter, Daniel
AU - Kahn, Yonatan
AU - Krnjaic, Gordan
N1 - Funding Information:
We gratefully acknowledge Peter Abbamonte for discussions and for pointing out that plasmons are the likely mechanism by which light dark matter couples to charged particles in condensed matter systems, and Lucas Wagner for many enlightening conversations which helped to bridge the gap between the languages of condensed matter physics and high-energy physics. In parallel, we want to acknowledge Alan Robinson and Emile Michaud for pointing out that plasmon interactions should impact low-energy reconstruction of electron recoils. None of the observations in this paper would be possible without the results we cite, but also without private conversations with the collaborations responsible which led to early discussions on the various possible background origins of observed excesses. We thus want to acknowledge (in alphabetical order) Dan Bauer, Karl Berggren, Julien Billard, Alvaro Chavarria, Juan Collar, Rouven Essig, Enectali Figueroa-Feliciano, Jules Gascon, Yonit Hochberg, Ziqing Hong, Tongyan Lin, Sam McDermott, Kaixuan Ni, Paolo Privitera, Matt Pyle, Karthik Ramanathan, Wolfgang Rau, Florian Reindl, Peter Sorenson, Javier Tiffenberg, Belina von Krosigk, and Tien-Tien Yu. We are especially grateful to Nikita Blinov, Torben Ferber, Jeff Filippini, Paddy Fox, Roni Harnik, Dan Hooper, Lauren Hsu, Sam McDermott, Harikrishnan Ramani, Albert Stebbins, and Belina von Krosigk for their feedback on early drafts of this paper. We thank the Gordon and Betty Moore Foundation and the American Physical Society for the support of the “New Directions in Light Dark Matter” workshop where the key idea for this work was conceived. Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. This work was supported in part by the Kavli Institute for Cosmological Physics at the University of Chicago through an endowment from the Kavli Foundation and its founder Fred Kavli.
PY - 2020/7/1
Y1 - 2020/7/1
N2 - We present a novel unifying interpretation of excess event rates observed in several dark matter direct-detection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of ∼10 Hz/kg. However, none of these persistent excesses has yet been reported as a dark matter signal because individually, each can be attributed to different well-motivated but unmodeled backgrounds, and taken together, they cannot be explained by dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process, consistent with exciting a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several single-electron threshold detectors. At least one of these scenarios also yields the correct relic density from thermal freeze-out. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.
AB - We present a novel unifying interpretation of excess event rates observed in several dark matter direct-detection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of ∼10 Hz/kg. However, none of these persistent excesses has yet been reported as a dark matter signal because individually, each can be attributed to different well-motivated but unmodeled backgrounds, and taken together, they cannot be explained by dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process, consistent with exciting a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several single-electron threshold detectors. At least one of these scenarios also yields the correct relic density from thermal freeze-out. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.
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U2 - 10.1103/PhysRevD.102.015017
DO - 10.1103/PhysRevD.102.015017
M3 - Article
AN - SCOPUS:85092421617
VL - 102
JO - Physical Review D
JF - Physical Review D
SN - 2470-0010
IS - 1
M1 - 015017
ER -