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1. Search for an eV-Scale Sterile Neutrino Using Improved High-Energy ${\nu }_{\mu }$ Event Reconstruction in IceCube

   https://doi.org/10.1103/PhysRevLett.133.201804  

   Abbasi, R; Ackermann, M; Adams, J; Agarwalla, S K; Aguilar, J A; Ahlers, M; Alameddine, J M; Amin, N M; Andeen, K; Argüelles, C; et al (November 2024, Physical Review Letters)

   This Letter presents the result of a $3+1$sterile neutrino search using 10.7 yr of IceCube data. We analyze atmospheric muon neutrinos that traverse the Earth with energies ranging from 0.5 to 100 TeV, incorporating significant improvements in modeling neutrino flux and detector response compared to earlier studies. Notably, for the first time, we categorize data into starting and throughgoing events, distinguishing neutrino interactions with vertices inside or outside the instrumented volume, to improve energy resolution. The best-fit point for a $3+1$model is found to be at ${\sin }^2\left(2{\theta }_{24}\right)=0.16$and $\mathrm{\Delta }{m}_{41}^2=3.5{\mathrm{eV}}^2$, which agrees with previous iterations of this Letter. The result is consistent with the null hypothesis of no sterile neutrinos with a $p$value of 3.1%. Published by the American Physical Society2024 

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2. Neutrino electromagnetic properties and the weak mixing angle at the LHC Forward Physics Facility

   https://doi.org/10.1103/PhysRevD.111.015029  

   Abraham, Roshan Mammen; Foroughi-Abari, Saeid; Kling, Felix; Tsai, Yu-Dai (January 2025, Physical Review D)

   The LHC produces an intense beam of highly energetic neutrinos of all three flavors in the forward direction, and the Forward Physics Facility (FPF) has been proposed to house a suite of experiments taking advantage of this opportunity. In this study, we investigate the FPF’s potential to probe the neutrino electromagnetic properties, including neutrino millicharge, magnetic moment, and charge radius. We find that, due to the large flux of tau neutrinos at the LHC, the FPF detectors will be able to provide more sensitive constraints on the tau neutrino magnetic moment and millicharge than previous measurements at DONUT, by searching for excess in low recoil energy electron scattering events. We also find that, by precisely measuring the rate of neutral current deep inelastic scattering events, the FPF detectors have the potential to obtain the strongest experimental bounds on the neutrino charge radius for the electron neutrino, and one of the leading bounds for the muon neutrino flavor. The same signature could also be used to measure the weak mixing angle, and we estimate that ${\sin }^2{\theta }_W$could be measured to about 3% precision at a scale $Q\sim 10\mathrm{GeV}$, shedding new light on the longstanding NuTeV anomaly. Published by the American Physical Society2025 

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3. Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector

   https://doi.org/10.1103/PhysRevD.110.082008  

   Kitagawa, H; Tada, T; Abe, K; Bronner, C; Hayato, Y; Hiraide, K; Hosokawa, K; Ieki, K; Ikeda, M; Kameda, J; et al (October 2024, Physical Review D)

   We present the results of the charge ratio ( $R$) and polarization ( $P_0^{\mu }$) measurements using decay electron events collected between September 2008 and June 2022 with the Super-Kamiokande detector. Because of its underground location and long operation, we are able to perform high-precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be $R=1.32\pm 0.02(\mathrm{stat}+\mathrm{syst})$at $E_{\mu }\cos {\theta }_{\text{Zenith}}={0.7}_{-0.2}^{+0.3}\mathrm{TeV}$, where $E_{\mu }$is the muon energy and ${\theta }_{\text{Zenith}}$is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while indicating a tension with the $\pi K$model of $1.9\sigma$. We also measured the muon polarization at the production location to be $P_0^{\mu }=0.52\pm 0.02(\mathrm{stat}+\mathrm{syst})$at the muon momentum of ${0.9}_{-0.1}^{+0.6}\mathrm{TeV}/c$at the surface of the mountain; this also suggests a tension with the Honda flux model of $1.5\sigma$. This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near $1\mathrm{TeV}/c$. These measurement results are useful to improve atmospheric neutrino simulations. Published by the American Physical Society2024 

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4. Search for a light sterile neutrino with 7.5 years of IceCube DeepCore data

   https://doi.org/10.1103/PhysRevD.110.072007  

   Abbasi, R; Ackermann, M; Adams, J; Agarwalla, S K; Aguilar, J A; Ahlers, M; Alameddine, J M; Amin, N M; Andeen, K; Argüelles, C; et al (October 2024, Physical Review D)

   We present a search for an eV-scale sterile neutrino using 7.5 years of data from the IceCube DeepCore detector. The analysis uses a sample of 21,914 events with energies between 5 and 150 GeV to search for sterile neutrinos through atmospheric muon neutrino disappearance. Improvements in event selection and treatment of systematic uncertainties provide greater statistical power compared to previous DeepCore sterile neutrino searches. Our results are compatible with the absence of mixing between active and sterile neutrino states, and we place constraints on the mixing matrix elements $|U_{\mu 4}{|}^2<0.0534$and $|U_{\tau 4}{|}^2<0.0574$at 90% CL under the assumption that $\mathrm{\Delta }{m}_{41}^2\ge 1{\mathrm{eV}}^2$. These null results add to the growing tension between anomalous appearance results and constraints from disappearance searches in the $3+1$sterile neutrino landscape. Published by the American Physical Society2024 

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5. Methods and stability tests associated with the sterile neutrino search using improved high-energy ${\nu }_{\mu }$ event reconstruction in IceCube

   https://doi.org/10.1103/PhysRevD.110.092009  

   Abbasi, R; Ackermann, M; Adams, J; Agarwalla, S K; Aguilar, J A; Ahlers, M; Alameddine, J M; Amin, N M; Andeen, K; Argüelles, C; et al (November 2024, Physical Review D)

   We provide supporting details for the search for a $3+1$sterile neutrino using data collected over 10.7 years at the IceCube Neutrino Observatory. The analysis uses atmospheric muon-flavored neutrinos from 0.5 to 100 TeV that traverse Earth to reach the IceCube detector and finds a best-fit point at ${\sin }^2\left(2{\theta }_{24}\right)=0.16$and $\mathrm{\Delta }{m}_{41}^2=3.5{\mathrm{eV}}^2$with a goodness-of-fit p value of 12% and consistency with the null hypothesis of no oscillations to sterile neutrinos with a p value of 3.1%. Several improvements were made over past analyses, which are reviewed in this article, including upgrades to the reconstruction and the study of sources of systematic uncertainty. We provide details of the fit quality and discuss stability tests that split the data for separate samples, comparing results. We find that the fits are consistent between split datasets. Published by the American Physical Society2024 

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