Limits on Electron Neutrino Disappearance from the KARMEN and LSND electron neutrino - Carbon Cross Section Data

This paper presents a combined analysis of the KARMEN and LSND nu_e-carbon cross section measurements within the context of a search for nu_e disappearance at high Delta m^2. KARMEN and LSND were located at 17.7 m and 29.8 m respectively from the neutrino source, so the consistency of the two measurements, as a function of antineutrino energy, sets strong limits on neutrino oscillations. Most of the allowed region from the nu_e disappearance analysis of the Gallium calibration data is excluded at >95% CL and the best fit point is excluded at 3.6$\sigma$. Assuming CPT conservation, comparisons are also made to the oscillation analyses of reactor antineutrino data.Comment: Published versio

Confronting the short-baseline oscillation anomalies with a single sterile neutrino and non-standard matter effects

We examine the MiniBooNE neutrino, MiniBooNE antineutrino and LSND antineutrino data sets in a two-neutrino $\stackrel{\tiny{(-)}}{\nu}_{\mu}\rightarrow\stackrel{\tiny{(-)}}{\nu}_e$ oscillation approximation subject to non-standard matter effects. We assume those effects can be parametrized by an $L$-independent effective potential, $V_s=\pm A_s$, experienced only by an intermediate, non-weakly-interacting (sterile) neutrino state which we assume participates in the oscillation, where $+/-$ corresponds to neutrino/antineutrino propagation. We discuss the mathematical framework in which such oscillations arise in detail, and derive the relevant oscillation probability as a function of the vacuum oscillation parameters $\Delta m^2$ and $\sin^22\theta_{\mu e}$, and the matter effect parameter $A_s$. We are able to successfully fit all three data sets, including the MiniBooNE low energy excess, with the following best-fit model parameters: $\Delta m^2=0.47$ eV$^2$, $\sin^22\theta_{\mu e}=0.010$, and $A_s=2.0\times10^{-10}$ eV. The $\chi^2$-probability for the best fit corresponds to 21.6%, to be compared to 6.8% for a fit where $A_s$ has been set to zero, corresponding to a (3+1) sterile neutrino oscillation model. We find that the compatibility between the three data sets corresponds to 17.4%, to be compared to 2.3% for $A_s=0$. Finally, given the fit results, we examine consequences for reactor, solar, and atmospheric oscillations. For this paper, the presented model is empirically driven, but the results obtained can be directly used to investigate various phenomenological interpretations such as non-standard matter effects.Comment: 19 pages, 11 figures, 1 tabl

Precision Measurement of sin^2 theta_W at a Reactor

This paper presents a strategy for measuring sin^2 theta_W to ~1% at a reactor-based experiment, using antineutrinos electron elastic scattering. This error is comparable to the NuTeV, SLAC E158, and APV results on sin^2 theta_W, but with substantially different contributions to the systematics. An improved method for identifying antineutrino proton events, which serve both as a background and as a normalization sample, is described. The measurement can be performed using the near detector of the presently proposed reactor-based oscillation experiments. We conclude that an absolute error of delta(sin^2 theta_W)=0.0019 may be achieved.Comment: To be Submitted to Phys. Rev.

Sterile Neutrino Fits to Short Baseline Neutrino Oscillation Measurements

This paper reviews short baseline oscillation experiments as interpreted within the context of one, two, and three sterile neutrino models associated with additional neutrino mass states in the ~1 eV range. Appearance and disappearance signals and limits are considered. We show that fitting short baseline data sets to a (3+3) model, defined by three active and three sterile neutrinos, results in an overall goodness of fit of 67%, and a compatibility of 90% among all data sets -- to be compared to the compatibility of 0.043% and 13% for a (3+1) and a (3+2) model, respectively. While the (3+3) fit yields the highest quality overall, it still finds inconsistencies with the MiniBooNE appearance data sets; in particular, the global fit fails to account for the observed MiniBooNE low-energy excess. Given the overall improvement, we recommend using the results of (3+2) and (3+3) fits, rather than (3+1) fits, for future neutrino oscillation phenomenology. These results motivate the pursuit of further short baseline experiments, such as those reviewed in this paper.Comment: Submitted to Advances in High Energy Physics Special Issue on Neutrino Physic

Short-baseline Neutrino Oscillation Waves in Ultra-large Liquid Scintillator Detectors

Powerful new multi-kiloton liquid scintillator neutrino detectors, including NOvA and LENA, will come on-line within the next decade. When these are coupled with a modest-power decay-at-rest (DAR) neutrino source at short-baseline, these detectors can decisively address the recent ambiguous signals for neutrino oscillations at high Delta m^2. These detectors are > 50 m long, and so with a DAR beam, the characteristic oscillation wave will be apparent over the length of the detector, providing a powerful verification of the oscillation phenomena. LENA can simultaneously perform numubar to nuebar appearance and nue to nue disappearance searches with unprecedented sensitivity. NOvA is likely limited to nue disappearance given its present design, but also has excellent sensitivity in the high Delta m^2 region. For the appearance channel, LENA could provide a stringent test of the LSND and MiniBooNE signal regions at > 5 sigma with a reduced fiducial volume of 5 kt and a 10 kW neutrino source. In addition, the LENA and NOvA disappearance sensitivities in nue mode are complementary to the recent reactor anomaly indicating possible nuebar disappearance and would cover this possible oscillation signal at the 3 sigma level.Comment: 24 pages, 8 figures, 9 table

Cyclotrons as Drivers for Precision Neutrino Measurements

As we enter the age of precision measurement in neutrino physics, improved flux sources are required. These must have a well-defined flavor content with energies in ranges where backgrounds are low and cross section knowledge is high. Very few sources of neutrinos can meet these requirements. However, pion/muon and isotope decay-at-rest sources qualify. The ideal drivers for decay-at-rest sources are cyclotron accelerators, which are compact and relatively inexpensive. This paper describes a scheme to produce decay-at-rest sources driven by such cyclotrons, developed within the DAEdALUS program. Examples of the value of the high precision beams for pursuing Beyond Standard Model interactions are reviewed. New results on a combined DAEdALUS--Hyper-K search for CP-violation that achieve errors on the mixing matrix parameter of 4 degrees to 12 degrees are presented.Comment: This paper was invited by the journal Advances in High Energy Physics for their upcoming special issue on "Neutrino Masses and Oscillations," which will be published on the 100th anniversary of Pontecorvo's birt

Measuring Active-to-Sterile Neutrino Oscillations with Neutral Current Coherent Neutrino-Nucleus Scattering

Light sterile neutrinos have been introduced as an explanation for a number of oscillation signals at $\Delta m^2 \sim 1$ eV$^2$. Neutrino oscillations at relatively short baselines provide a probe of these possible new states. This paper describes an accelerator-based experiment using neutral current coherent neutrino-nucleus scattering to strictly search for active-to-sterile neutrino oscillations. This experiment could, thus, definitively establish the existence of sterile neutrinos and provide constraints on their mixing parameters. A cyclotron-based proton beam can be directed to multiple targets, producing a low energy pion and muon decay-at-rest neutrino source with variable distance to a single detector. Two types of detectors are considered: a germanium-based detector inspired by the CDMS design and a liquid argon detector inspired by the proposed CLEAR experiment.Comment: 10 pages, 7 figure

Improved Parameterization of K+K^+ Production in p-Be Collisions at Low Energy Using Feynman Scaling

This paper describes an improved parameterization for proton-beryllium production of secondary $K^{+}$ mesons for experiments with primary proton beams from 8.89 to 24 GeV. The parameterization is based on Feynman scaling in which the invariant cross section is described as a function of $x_{F}$ and $p_{T}$. This method is theoretically motivated and provides a better description of the energy dependence of kaon production at low beam energies than other parameterizations such as the commonly used "Modified Sanford-Wang" model. This Feynman scaling parameterization has been used for the simulation of the neutrino flux from the Booster Neutrino Beam (BNB) at Fermilab and has been shown to agree with the neutrino interaction data from the SciBooNE experiment. This parameterization will also be useful for future neutrino experiments with low primary beam energies, such as those planned for the Project X accelerator.Comment: 15 pages, 13 figure

New Clues About Light Sterile Neutrinos: Preference for Models with Damping Effects in Global Fits

This article reports global fits of short-baseline neutrino data to oscillation models involving light sterile neutrinos. In the commonly-used 3+1 plane wave model, there is a well-known 4.9$\sigma$ tension between data sets sensitive to appearance and disappearance of neutrinos. We find that models that damp the oscillation prediction for the reactor data sets, especially at low energy, substantially improve the fits and reduce the tension. We consider two such scenarios. The first introduces one sterile neutrino (3+1) and the Quantum Mechanical wavepacket effect that accounts for the source size in reactor experiments. We find that inclusion of the wavepacket effect greatly improves the overall fit compared to the null model by $\Delta \chi^2/\textrm{dof}=60.2/4$ ($7\sigma$ improvement) with best-fit $\Delta m^2=1.4~\textrm{eV}^2$ and wavepacket length of 67 fm; internal tension is reduced to 3.6$\sigma$. If reactor-data only is fit, that the wavepacket preferred length is 91 fm ($>20$ fm at 99\% CL). The second model introduces oscillations involving sterile flavor and allows the decay of the heavier, mostly sterile, mass state $\nu_4$. This model introduces a damping term similar to the wavepacket effect, but across all experiments. Compared to null, this has a $\Delta \chi^2/\textrm{dof}=60.6/4$ ($7\sigma$ improvement) with preferred $\Delta m^2=1.4~\textrm{eV}^2$ and decay $\Gamma = 0.35~\textrm{eV}$; and internal tension of 3.7$\sigma$.Comment: Errors are the prospect plot updated from the collaboration. Tension figures have updated plot styl