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Evidence for nu_mu -> nu_e Neutrino Oscillations from LSND

LSND Collaboration, C. Athanassopoulos, L. B. Auerbach, R. L. Burman, D. O. Caldwell, E. D. Church, I. Cohen, J. B. Donahue, A. Fazely, F. J. Federspiel, G. T. Garvey, R. M. Gunasingha, R. Imlay, K. Johnston, H. J. Kim, W. C. Louis, R. Majkic, K. McIlhany, W. Metcalf, G. B. Mills, R. A. Reeder, V. Sandberg, D. Smith, I. Stancu, W. Strossman, R. Tayloe, G. J. VanDalen, W. Vernon, N. Wadia, J. Waltz, D. H. White, D. Works, Y. Xiao, S. Yellin

Abstract

A search for nu_mu -> nu_e oscillations has been conducted with the LSND apparatus at the Los Alamos Meson Physics Facility. Using nu_mu from pi^+ decay in flight, the nu_e appearance is detected via the charged-current reaction C(nu_e,e^-)X. Two independent analyses observe a total of 40 beam-on high-energy electron events (60 < E_e < 200 MeV) consistent with the above signature. This number is significantly above the 21.9 +- 2.1 events expected from the nu_e contamination in the beam and the beam-off background. If interpreted as an oscillation signal, the observed oscillation probability of (2.6 +- 1.0 +- 0.5) x 10^{-3} is consistent with the previously reported nu_mu_bar -> nu_e_bar oscillation evidence from LSND.

Evidence for nu_mu -> nu_e Neutrino Oscillations from LSND

Abstract

A search for nu_mu -> nu_e oscillations has been conducted with the LSND apparatus at the Los Alamos Meson Physics Facility. Using nu_mu from pi^+ decay in flight, the nu_e appearance is detected via the charged-current reaction C(nu_e,e^-)X. Two independent analyses observe a total of 40 beam-on high-energy electron events (60 < E_e < 200 MeV) consistent with the above signature. This number is significantly above the 21.9 +- 2.1 events expected from the nu_e contamination in the beam and the beam-off background. If interpreted as an oscillation signal, the observed oscillation probability of (2.6 +- 1.0 +- 0.5) x 10^{-3} is consistent with the previously reported nu_mu_bar -> nu_e_bar oscillation evidence from LSND.

Paper Structure

This paper contains 1 section, 2 equations, 3 figures, 2 tables.

Table of Contents

  1. Acknowledgments

Figures (3)

  • Figure 1: Calculated $\nu_\mu$ and $\nu_e$ DIF fluxes at the detector center from the A6 target (solid histograms) and from the A1+A2 targets (dashed histograms).
  • Figure 2: Timing likelihoods for (a) the entire event and (b) the Čerenkov region only. (c) Čerenkov-to-scintillation density ratio, $\rho$. (d) Projected track-length to the tank wall intersection. (a)-(c) correspond to all (beam on+off) DIF data after the pre-selection and (d) after all other cuts have been applied. All superimposed distributions (dashed) correspond to the DIF-MC simulation, normalized to the same areas.
  • Figure 3: The 95% confidence level region for the DIF $\nu_\mu \to \nu_e$ along with the favored regions from the LSND $\bar{\nu}_\mu \to \bar{\nu}_e$ DAR measurement (dotted contours).