More Like this

1. First Measurement of ${\nu }_e$ and ${\nu }_{\mu }$ Interaction Cross Sections at the LHC with FASER’s Emulsion Detector

   https://doi.org/10.1103/PhysRevLett.133.021802  

   Abraham, Roshan Mammen; Anders, John; Antel, Claire; Ariga, Akitaka; Ariga, Tomoko; Atkinson, Jeremy; Bernlochner, Florian U; Boeckh, Tobias; Boyd, Jamie; Brenner, Lydia; et al (July 2024, Physical Review Letters)

   The first results of the study of high-energy electron neutrino ( ${\nu }_e$) and muon neutrino ( ${\nu }_{\mu }$) charged-current interactions in the $\mathrm{FASER}\nu$emulsion-tungsten detector of the FASER experiment at the LHC are presented. A 128.8 kg subset of the $\mathrm{FASER}\nu$volume was analyzed after exposure to $9.5{\mathrm{fb}}^{-1}$of $\sqrt{s}=13.6\mathrm{TeV}$ $pp$data. Four (eight) ${\nu }_e$( ${\nu }_{\mu }$) interaction candidate events are observed with a statistical significance of $5.2\sigma$( $5.7\sigma$). This is the first direct observation of ${\nu }_e$interactions at a particle collider and includes the highest-energy ${\nu }_e$and ${\nu }_{\mu }$ever detected from an artificial source. The interaction cross section per nucleon $\sigma /E_{\nu }$is measured over an energy range of 560–1740 GeV (520–1760 GeV) for ${\nu }_e$( ${\nu }_{\mu }$) to be $\left({1.2}_{-0.7}^{+0.8}\right)\times {10}^{-38}{\mathrm{cm}}^2{\mathrm{GeV}}^{-1}$[ $(0.5\pm 0.2)\times {10}^{-38}{\mathrm{cm}}^2{\mathrm{GeV}}^{-1}$], consistent with standard model predictions. These are the first measurements of neutrino interaction cross sections in those energy ranges. Published by the American Physical Society2024 

   more » « less
2. Dual-Baseline Search for Active-to-Sterile Neutrino Oscillations in NOvA

   https://doi.org/10.1103/PhysRevLett.134.081804  

   Acero, M A; Acharya, B; Adamson, P; Anfimov, N; Antoshkin, A; Arrieta-Diaz, E; Asquith, L; Aurisano, A; Back, A; Balashov, N; et al (February 2025, Physical Review Letters)

   We report a search for neutrino oscillations to sterile neutrinos under a model with three active and one sterile neutrinos ( $3+1$model). This analysis uses the NOvA detectors exposed to the NuMI beam, running in neutrino mode. The data exposure, $13.6\times {10}^{20}$protons on target, doubles that previously analyzed by NOvA, and the analysis is the first to use ${\nu }_{\mu }$charged-current interactions in conjunction with neutral-current interactions. Neutrino samples in the near and far detectors are fitted simultaneously, enabling the search to be carried out over a $\mathrm{\Delta }{m}_{41}^2$range extending 2 (3) orders of magnitude above (below) $1{\mathrm{eV}}^2$. NOvA finds no evidence for active-to-sterile neutrino oscillations under the $3+1$model at 90% confidence level. New limits are reported in multiple regions of parameter space, excluding some regions currently allowed by IceCube at 90% confidence level. We additionally set the most stringent limits for anomalous ${\nu }_{\tau }$appearance for $\mathrm{\Delta }{m}_{41}^2\le 3{\mathrm{eV}}^2$. Published by the American Physical Society2025 

   more » « less
3. First Indication of Solar ${}^8\mathrm{B}$ Neutrinos via Coherent Elastic Neutrino-Nucleus Scattering with XENONnT

   https://doi.org/10.1103/PhysRevLett.133.191002  

   Aprile, E; Aalbers, J; Abe, K; Ahmed_Maouloud, S; Althueser, L; Andrieu, B; Angelino, E; Antón_Martin, D; Arneodo, F; Baudis, L; et al (November 2024, Physical Review Letters)

   We present the first measurement of nuclear recoils from solar ${}^8\mathrm{B}$neutrinos via coherent elastic neutrino-nucleus scattering with the XENONnT dark matter experiment. The central detector of XENONnT is a low-background, two-phase time projection chamber with a 5.9 t sensitive liquid xenon target. A blind analysis with an exposure of $3.51\mathrm{t}\times \mathrm{yr}$resulted in 37 observed events above 0.5 keV, with ( ${26.4}_{-1.3}^{+1.4}$) events expected from backgrounds. The background-only hypothesis is rejected with a statistical significance of $2.73\sigma$. The measured ${}^8\mathrm{B}$solar neutrino flux of $\left({4.7}_{-2.3}^{+3.6}\right)\times {10}^6{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$is consistent with results from the Sudbury Neutrino Observatory. The measured neutrino flux-weighted $\mathrm{CE}\nu \mathrm{NS}$cross section on Xe of $\left({1.1}_{-0.5}^{+0.8}\right)\times {10}^{-39}{\mathrm{cm}}^2$is consistent with the Standard Model prediction. This is the first direct measurement of nuclear recoils from solar neutrinos with a dark matter detector. Published by the American Physical Society2024 

   more » « less
4. Solar neutrinos and ${\nu }_2$ visible decays to ${\nu }_1$

   https://doi.org/10.1103/PhysRevD.109.013003  

   de_Gouvêa, André; Weill, Jean; Sen, Manibrata (January 2024, Physical Review D)

   Experimental bounds on the neutrino lifetime depend on the nature of the neutrinos and the details of the potentially new physics responsible for neutrino decay. In the case where the decays involve active neutrinos in the final state, the neutrino masses also qualitatively impact how these manifest themselves experimentally. In order to further understand the impact of nonzero neutrino masses, we explore how observations of solar neutrinos constrain a very simple toy model. We assume that neutrinos are Dirac fermions and there is a new massless scalar that couples to neutrinos such that a heavy neutrino— ${\nu }_2$with mass $m_2$—can decay into a lighter neutrino— ${\nu }_1$with mass $m_1$—and a massless scalar. We find that the constraints on the new physics coupling depend, sometimes significantly, on the ratio of the daughter-to-parent neutrino masses and that, for large-enough values of the new physics coupling, the “dark side” of the solar neutrino parameter space— ${\sin }^2{\theta }_{12}\sim 0.7$—provides a reasonable fit to solar neutrino data, if only ${}^8\mathrm{B}$or ${}^7\mathrm{Be}$neutrino data alone are considered, but no allowed region is found in the combined analysis. Our results generalize to other neutrino-decay scenarios, including those that mediate ${\nu }_2\to {\nu }_1{\overline{\nu }}_3{\nu }_3$when the neutrino mass ordering is inverted mass and $m_2>m_1\gg m_3$, the mass of ${\nu }_3$. Published by the American Physical Society2024 

   more » « less
5. Enhanced muonization by active-sterile neutrino mixing in protoneutron stars

   https://doi.org/10.1103/PhysRevD.110.043007  

   Ray, Anupam; Qian, Yong-Zhong (August 2024, Physical Review D)

   We study ${\nu }_{\mu }\text{−}{\nu }_s$and ${\overline{\nu }}_{\mu }\text{−}{\overline{\nu }}_s$mixing in the protoneutron star (PNS) created in a core-collapse supernova (CCSN). We point out the importance of the feedback on the general composition of the PNS in addition to the obvious feedback on the ${\nu }_{\mu }$lepton number. We show that for our adopted mixing parameters $\delta m^2\sim {10}^2{\mathrm{keV}}^2$and ${\sin }^{2}2\theta$consistent with the current constraints, sterile neutrino production is dominated by the Mikheyev–Smirnov–Wolfenstein conversion of ${\overline{\nu }}_{\mu }$into ${\overline{\nu }}_s$and that the subsequent escape of ${\overline{\nu }}_s$increases the ${\nu }_{\mu }$lepton number, which in turn enhances muonization of the PNS primarily through ${\nu }_{\mu }+n\to p+{\mu }^{-}$. While these results are qualitatively robust, their quantitative effects on the dynamics and active neutrino emission of core-collapse supernovae should be evaluated by including ${\nu }_{\mu }\text{−}{\nu }_s$and ${\overline{\nu }}_{\mu }\text{−}{\overline{\nu }}_s$mixing in the simulations. Published by the American Physical Society2024 

   more » « less