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Teppei Katori

Publications and source records attributed to Teppei Katori.

33 records · Page 2Linked to original sources

Short Baseline Neutrino Oscillation Experiments

Series of short baseline neutrino oscillation experiments provided unexpected results, and now they are called short baseline anomalies, and all indicates an existence of sterile neutrinos with a mass scale around 1~eV. The signals of short baseline anomalies are reported from 4 different classes of experiments. However, at this moment, there is no convincing theoretical model to explain such sterile neutrinos, and a single experiment to confirm 1~eV sterile neutrinos may be challenging. In this short note, we describe classes of short baseline neutrino oscillation experiments and their goals.

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Beyond Standard Model Searches in the MiniBooNE Experiment

The MiniBooNE Experiment has contributed substantially to beyond standard model searches in the neutrino sector. The experiment was originally designed to test the $Δm^2$~1 eV$^2$ region of the sterile neutrino hypothesis by observing $ν_e$ ($\barν_e$) charged current quasi-elastic signals from a $ν_μ$ ($\barν_μ$) beam. MiniBooNE observed excesses of $ν_e$ and $\barν_e$-candidate events in neutrino and anti-neutrino mode, respectively. To date, these excesses have not been explained within the neutrino Standard Model ($ν$SM), the Standard Model extended for three massive neutrinos. Confirmation is required by future experiments such as MicroBooNE. MiniBooNE also provided an opportunity for precision studies of Lorentz violation. The results set strict limits for the first time on several parameters of the Standard Model-Extension, the generic formalism for considering Lorentz violation. Most recently, an extension to MiniBooNE running, with a beam tuned in beam-dump mode, is being performed to search for dark sector particles. This review describes these studies, demonstrating that short baseline neutrino experiments are rich environments in new physics searches.

hep-ex↗

Tests of Lorentz and CPT violation with MiniBooNE neutrino oscillation excesses

Violation of Lorentz invariance and CPT symmetry is a predicted phenomenon of Planck-scale physics. Various types of data are analyzed to search for Lorentz violation under the Standard-Model Extension (SME) framework, including neutrino oscillation data. MiniBooNE is a short-baseline neutrino oscillation experiment at Fermilab. The measured excesses from MiniBooNE cannot be reconciled within the neutrino Standard Model; thus it might be a signal of new physics, such as Lorentz violation. We have analyzed the sidereal time dependence of MiniBooNE data for signals of the possible breakdown of Lorentz invariance in neutrinos. In this brief review, we introduce Lorentz violation, the neutrino sector of the SME, and the analysis of short-baseline neutrino oscillation experiments. We then present the results of the search for Lorentz violation in MiniBooNE data. This review is based on the published result (ArXiv:1109.3480).

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Charged Current Quasi-Elastic Cross Section Measurements in MiniBooNE

The neutrino-induced charged-current quasi-elastic (CCQE, $ν_l+n\to l^-+p$ or $\barν_l+p\to l^++n$) interaction is the most abundant interaction around 1 GeV, and it is the most fundamental channel to study neutrino oscillations. Recently, MiniBooNE published both muon neutrino and muon anti-neutrino double differential cross sections on carbon. In this review, we describe the details of these analyses and include some historical remarks.

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MicroBooNE light collection system

MicroBooNE is a neutrino experiment located on axis in the Booster Neutrino Beamline, at Fermi National Accelerator Laboratory, scheduled to begin data collection in 2014. The MicroBooNE detector consists of two main components: a large liquid argon time projection chamber (LArTPC), and a light collection system. Thirty two 8-inch diameter cryogenic photomultiplier tubes (PMTs) will detect the scintillation light generated in the liquid argon. In this article, we describe the basic features of the system and current status of MicroBooNE light collection system.

physics.ins-det↗

Testing Lorentz Symmetry with the Double Chooz Experiment

The Double Chooz reactor-based oscillation experiment searches for an electron antineutrino disappearance signal to investigate the neutrino mass matrix mixing angle theta 13. Double Chooz's reported evidence for this disappearance is generally interpreted as mass-driven mixing through this parameter. However, the electron antineutrino candidates collected by the experiment can also be used to search for a signature of the violation of Lorentz invariance. We study the sidereal time dependence of the antineutrino signal rate and probe Lorentz violation within the Standard-Model Extension (SME) framework. We find that the data prefer the sidereal time independent solution, and a number of limits are applied to the relevant SME coefficients, including the first constraints on those associated with Lorentz violation in the e-tau mixing sector.

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Meson Exchange Current (MEC) Models in Neutrino Interaction Generators

Understanding of the so-called 2 particle-2 hole (2p-2h) effect is an urgent program in neutrino interaction physics for current and future oscillation experiments. Such processes are believed to be responsible for the event excesses observed by recent neutrino experiments. The 2p-2h effect is dominated by the meson exchange current (MEC), and is accompanied by a 2-nucleon emission from the primary vertex, instead of a single nucleon emission from the charged-current quasi-elastic (CCQE) interaction. Current and future high resolution experiments can potentially nail down this effect. For this reason, there are world wide efforts to model and implement this process in neutrino interaction simulations. In these proceedings, I would like to describe how this channel is modeled in neutrino interaction generators.

nucl-th↗

Cross section analyses in MiniBooNE and SciBooNE experiments

The MiniBooNE experiment (2002-2012) and the SciBooNE experiment (2007-2008) are modern high statistics neutrino experiments, and they developed many new ideas in neutrino cross section analyses. In this note, I discuss selected topics of these analyses.

hep-ex↗

Tests of Lorentz and CPT violation with neutrinos

Lorentz violation is a predicted phenomenon from the Planck scale physics. Although the three active massive neutrino framework with the Standard Model (SM), so-called the neutrino Standard Model (nuSM), is successful, series of signals not understood within the nuSM suggest neutrino physics may be the first place to see the physics beyond the SM, such as Lorentz violation. Especially, neutrino oscillations are the natural interferometer and they are sensitive to the Lorentz violation. The LSND oscillation signal was analyzed under the Standard Model Extension (SME) framework, and it was found that the oscillation data was consistent with no Lorentz violation, but data cannot reject Lorentz violation hypothesis with order ~10^{-17}. By assuming LSND signal was due to the Lorentz violation, a global phenomenological model was made to describe all known oscillation data including the LSND signal. The model also predicted the signal for MiniBooNE at the low energy region. Later, MiniBooNE announced an event excess at the low energy region. However, the oscillation candidate signals from MiniBooNE were consistent with no Lorentz violation. The limit obtained by MiniBooNE and MINOS on the e-mu sector reject the simple scenario to explain LSND signal with Lorentz violation. Meantime, MINOS and IceCube set tight limits on the mu-tau sector Lorentz violation. The last untested channel, the e-tau Lorentz violating mixing, was tested using reactor disappearance data from Double Chooz. However, Double Chooz data was consistent with flat, and sidereal time dependent Lorentz violation hypothesis is rejected. Combinations of all oscillation data from LSND, MiniBooNE, MINOS, IceCube, and Double Chooz provide very tight constraint for a possible Lorentz violation in the neutrino sector in terrestrial level.

hep-ph↗

MicroBooNE, A Liquid Argon Time Projection Chamber (LArTPC) Neutrino Experiment

Liquid Argon time projection chamber (LArTPC) is a promising detector technology for future neutrino experiments. MicroBooNE is an upcoming LArTPC neutrino experiment which will be located on-axis of Booster Neutrino Beam (BNB) at Fermilab, USA. The R&D efforts on this detection method and related neutrino interaction measurements are discussed.

hep-ex↗

Test for Lorentz and CPT Violation with the MiniBooNE Low-Energy Excess

The MiniBooNE experiment is a $ν_μ\toν_e$ and $\barν_μ\to\barν_e$ appearance neutrino oscillation experiment at Fermilab. The neutrino mode oscillation analysis shows an excess of $ν_e$ candidate events in the low-energy region. These events are analyzed under the SME formalism, utilizing the short baseline approximation. The preliminary result shows the time independent solution is favored. The relationship with the SME parameters extracted from the LSND experiment is discussed. The systematic error analysis and antineutrino mode analysis are outlined.

hep-ph↗

First Measurement of Muon Neutrino Charged Current Quasielastic (CCQE) Double Differential Cross Section

Using a high statistics sample of muon neutrino charged current quasielastic (CCQE) events, we report the first measurement of the double differential cross section as a function of muon energy and angle for this process. The result features reduced model dependence and supplies the most complete information on neutrino CCQE scattering to date. Measurements of the absolute cross section as a function of neutrino energy and the single differential cross section as a function of 4-momentum transfer squared are also provided, largely to facilitate comparison with prior measurements. This data is of particular use for understanding the axial-vector form factor of the nucleon as well as improving the simulation of low energy neutrino interactions on nuclear targets, which is of particular relevance for experiments searching for neutrino oscillations.

hep-ex↗

Neutrino Cross Section Measurements for Long-Baseline Accelerator-based Neutrino Oscillation Experiments

Neutrino oscillations are clear evidence for physics beyond the standard model. The goal of next-generation neutrino oscillation experiments is to find a non-zero $θ_{13}$, the last mixing matrix element for which we only know an upper limit. For this, next-generation long-baseline neutrino oscillation experiments require an order of magnitude better sensitivities. In particular, accelerator-based experiments such as T2K and NOvA experiments need (1) good neutrino energy reconstruction for the precise measurement of $Δm^2_{32}$ and $sin^22θ_{23}$, and (2) good background prediction to measure $ν_e$ appearance signals. Current and near future high statistics neutrino experiments, such as K2K, MiniBooNE, SciBooNE, MINOS, and MINERvA help both (1) and (2) by precise signal and background channel measurements.

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Charged-Current Interaction Measurements in MiniBooNE

Neutrino oscillation is the only known phenomenon for physics beyond the standard model. To investigate this phenomenon, the understanding of low energy neutrino scattering (200<E<2000 MeV) is the crucial task for high energy physicists. In this energy region, the charged current quasi-elastic (CCQE) neutrino interaction is the dominant process, and experiments require a precise model to predict signal samples. Using a high-statistics sample of muon neutrino CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events on carbon. The extracted parameters include an effective axial mass, MA=1.23 +- 0.20 GeV, and a Pauli-blocking parameter, kappa = 1.019 +- 0.011.

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Global three-parameter model for neutrino oscillations using Lorentz violation

A model of neutrino oscillations is presented that has only three degrees of freedom and is consistent with existing data. The model is a subset of the renormalizable sector of the Standard-Model Extension (SME), and it offers an alternative to the standard three-neutrino massive model. All classes of neutrino data are described, including solar, reactor, atmospheric, and LSND oscillations. The disappearance of solar neutrinos is obtained without matter-enhanced oscillations. Quantitative predictions are offered for the ongoing MiniBooNE experiment and for the future experiments OscSNS, NOvA, and T2K.

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