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

The MiniBooNE experiment is a $\nu_\mu\to\nu_e$ and $\bar\nu_\mu\to\bar\nu_e$ appearance neutrino oscillation experiment at Fermilab. The neutrino mode oscillation analysis shows an excess of $\nu_e$ 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.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 28-July 2, 201

Search for Quantum Gravity Using Astrophysical Neutrino Flavour with IceCube

Along their long propagation from production to detection, neutrinos undergo flavour conversions that convert their types or flavours 1,2. High-energy astrophysical neutrinos propagate unperturbed over a billion light years in vacuum 3 and are sensitive to small effects caused by new physics. Effects of quantum gravity 4 are expected to appear at the Planck energy scale. Such a high-energy universe would have existed only immediately after the Big Bang and is inaccessible by human technologies. On the other hand, quantum gravity effects may exist in our low-energy vacuum 5–8, but are suppressed by inverse powers of the Planck energy. Measuring the coupling of particles to such small effects is difficult via kinematic observables, but could be observable through flavour conversions. Here we report a search with the IceCube Neutrino Observatory, using astrophysical neutrino flavours 9,10 to search for new space–time structure. We did not find any evidence of anomalous flavour conversion in the IceCube astrophysical neutrino flavour data. We apply the most stringent limits of any known technologies, down to 10 −42 GeV −2 with Bayes factor greater than 10 on the dimension-six operators that parameterize the space–time defects. We thus unambiguously reach the parameter space of quantum-gravity-motivated physics.</p

A Measurement Of The Muon Neutrino Charged Current Quasielastic Interaction And A Test Of Lorentz Violation With The Miniboone Experiment

Thesis (Ph.D.) - Indiana University, Physics, 2008The Mini-Booster neutrino experiment (MiniBooNE) at Fermi National Accelerator Laboratory (Fermilab) is designed to search for &nu;&mu;&ndash;&nu;e appearance neutrino oscillations. Muon neutrino charged-current quasi-elastic (CCQE) interactions (&nu;&mu;+n&rarr;&mu;+p) make up roughly 40% of our data sample, and it is used to constrain the background and cross sections for the oscillation analysis. Using high&ndash;statistics MiniBooNE CCQE data, the muon-neutrino CCQE cross section is measured. The nuclear model is tuned precisely using the MiniBooNE data. The measured total cross section is &sigma;=(1.058&plusmn;0.003(stat)&plusmn;0.111(syst)) &times;10-38 cm2 at the MiniBooNE muon neutrino beam energy (700&ndash;800 MeV). &nu;e appearance candidate data is also used to search for Lorentz violation. Lorentz symmetry is one of the most fundamental symmetries in modern physics. Neutrino oscillations offer a new method to test it. We found that the MiniBooNE result is not well-described using Lorentz violation, however further investigation is required for a more conclusive result

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.Comment: 6 pages, 6 figures, Proceedings of the 6th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt09

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&lt;E&lt;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