28 research outputs found

    A multi-signature approach to low-scale sterile neutrino phenomenology

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    Since the discovery of non-zero neutrino masses, through the observation of neutrino flavour oscillations, we had a plethora of successful experiments which have made increasingly precise measurements of the mixing angles and mass-differences that drive the phenomena. In this thesis we highlight the fact that there is still significant room for new physics, however, when one removes the assumption of unitarity of the 3x3 neutrino mixing matrix, an assumption inherent in the 3ν paradigm. We refit all global data to show just how much non-unitarity is currently allowed. The canonical way that such a non-unitarity is introduced to the 3x3 neutrino mixing matrix is by the addition of additional neutral fermions, singlets under the Standard Model gauge group. These “Sterile Neutrinos” have a wide range of the- oretical and phenomenological implications. Alongside the sensitivity non-unitarity measurements have to sterile neutrinos, in this thesis we will study in detail two additional signatures of low-scale sterile neutrinos; the case of one or more light O(1eV) sterile neutrinos detected by their effect on neutrino flavour oscillations, and heavier O(100 MeV) detected via their subsequent decay to Standard Model particles. These two regimes have markedly different phenomenology, but are both measurable at terrestrial short-baseline experiments. We consistently use the Fermilab Short-Baseline Neutrino program as a concrete example which would produce world-leading bounds in both scenarios

    The Grizzly, December 4, 1981

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    Dealing With Financial Pressure • EcBA Department Interviews for New Positions • Freshman Relates Pre-Collegiate Experiences in Japan • Union Evaluation Prompts Improvement • Campus-wide Planning Meeting Sets Competitive Goals for UC • Residents Fix Up Curtis Hall • Lucas Named To PaCIE • \u27Messiah\u27 Rehearsal Open to Public • Jarvis and Rutherford in Last Coffeehouse • Best Albums of 1981 • Senior Poet Honored Nationally • New Wrestlers Lead the Way • Girls B-Ball Prime for Opener • Baseball Team Has New Skipper • Men\u27s Swimmers Take Third Place • Hoopsters Off to Slow Start • Gymnasts Pleasing • Women\u27s Swim Team Prepares for Tough Schedule • Mike Fagan All-MAChttps://digitalcommons.ursinus.edu/grizzlynews/1069/thumbnail.jp

    MeV-scale sterile neutrino decays at the Fermilab Short-Baseline Neutrino program

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    Nearly-sterile neutrinos with masses in the MeV range and below would be produced in the beam of the Short-Baseline Neutrino (SBN) program at Fermilab. In this article, we study the potential for SBN to discover these particles through their subsequent decays in its detectors. We discuss the decays which will be visible at SBN in a minimal and non-minimal extension of the Standard Model, and perform simulations to compute the parameter space constraints which could be placed in the absence of a signal. We demonstrate that the SBN programme can extend existing bounds on well constrained channels such as N → νl+l− and N → l±π∓ while, thanks to the strong particle identification capabilities of liquid-Argon technology, also place bounds on often neglected channels such as N → νγ and N → νπ0. Furthermore, we consider the phenomenological impact of improved event timing information at the three detectors. As well as considering its role in background reduction, we note that if the light-detection systems in SBND and ICARUS can achieve nanosecond timing resolution, the effect of finite sterile neutrino mass could be directly observable, providing a smoking-gun signature for this class of models. We stress throughout that the search for heavy nearly-sterile neutrinos is a complementary new physics analysis to the search for eV-scale oscillations, and would extend the BSM programme of SBN while requiring no beam or detector modifications

    MicroBooNE tests of the MiniBooNE Low Energy Excess

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    <p>The MiniBooNE Low Energy Excess (LEE) is the observation of anomalous events, whose true origin could be attributed to either electrons or photons in the detector as MiniBooNE lacked the power to distinguish them. One of the primary goals of MicroBooNE is to address this issue of the underlying source of the LEE, using Liquid Argon Time Projection Chamber technology to enable electron/photon separation. Before answering such a question one must find a way to model the MiniBooNE LEE in MicroBooNE. The reconstructed excess that was observed is highly affected by both the detector response and the analysis selection itself and their effects must be removed before mapping it to MicroBooNE. In this poster we describe this unfolding process, and show the end results of the true unfolded distributions for two well motivated LEE hypothesis: a) electrons from an increased nue charged current event rate and (b) photons due to neutral current Delta production with subsequent radiative decay.</p

    Unitarity and the three flavor neutrino mixing matrix

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    U(1) ′ mediated decays of heavy sterile neutrinos in MiniBooNE

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    The MiniBooNE low-energy excess is a long-standing problem which has received further confirmation with a reanalysis using newly collected data, with the anomaly now at the 4.8σ level. In this paper we propose a novel explanation which advocates a low-energy sector containing Z0 bosons with GeV-scale masses and sterile neutrinos with masses around 100–500 MeV. We show that this scenario provides excellent spectral agreement with the MiniBooNE low-energy excess in the form of Z0 -mediated neutral current production of heavy sterile states, a fraction of whose subsequent decay to eþe− pairs are misidentified as single electronlike electromagnetic showers. Our model inscribes itself in the broad class of models in which sterile neutrinos are charged under new interactions, allowing new couplings to hiddensector physics. Alongside the electronlike MiniBooNE signature this model also predicts a novel, lowbackground, signal in LArTPC detectors such as MicroBooNE consisting of two distinguishable electronlike electromagnetic showers originating from a single vertex

    Grid-based minimization at scale: Feldman-Cousins corrections for light sterile neutrino search

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    High Energy Physics (HEP) experiments generally employ sophisticated statistical methods to present results in searches of new physics. In the problem of searching for sterile neutrinos, likelihood ratio tests are applied to short-baseline neutrino oscillation experiments to construct confidence intervals for the parameters of interest. The test statistics of the form Δχ2 is often used to form the confidence intervals, however, this approach can lead to statistical inaccuracies due to the small signal rate in the region-of-interest. In this paper, we present a computational model for the computationally expensive Feldman-Cousins corrections to construct a statistically accurate confidence interval for neutrino oscillation analysis. The program performs a grid-based minimization over oscillation parameters and is written in C++. Our algorithms make use of vectorization through Eigen3, yielding a single-core speed-up of 350 compared to the original implementation, and achieve MPI data parallelism by employing DIY. We demonstrate the strong scaling of the application at High-Performance Computing (HPC) sites. We utilize HDF5 along with HighFive to write the results of the calculation to file
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