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Register a new userPrecision constraints for three-flavor neutrino oscillations from the full MINOS+ and MINOS data set
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MINOS+ Collaboration: P. Adamson
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We report the final measurement of the neutrino oscillation parameters $Delta m^2_{32}$ and $sin^2theta_{23}$ using all data from the MINOS and MINOS+ experiments. These data were collected using a total exposure of $23.76 times 10^{20}$ protons on target producing $ u_{mu}$ and $overline{ u_mu}$ beams and 60.75 kt$cdot$yr exposure to atmospheric neutrinos. The measurement of the disappearance of $ u_{mu}$ and the appearance of $ u_e$ events between the Near and Far detectors yields $|Delta m^2_{32}|=2.40^{+0.08}_{-0.09}~(2.45^{+0.07}_{-0.08}) times 10^{-3}$ eV$^2$ and $sin^2theta_{23} = 0.43^{+0.20}_{-0.04} ~(0.42^{+0.07}_{-0.03})$ at 68% C.L. for Normal (Inverted) Hierarchy.
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The MINOS experiment ran from 2003 until 2012 and collected a data sample including 10.71x10^20 protons-on-target (POT) of beam neutrinos, 3.36x10^20 POT of beam antineutrinos and an atmospheric neutrino exposure of 37.88 kt-yrs. The final measurement of the atmospheric neutrino oscillation parameters, dm^2_32 and theta_23, came from a full three flavour oscillation analysis of the combined CC nu_mu and CC anti-nu_mu beam and atmospheric samples and the CC nu_e and CC anti-nu_e appearance samples. This analysis yielded the most precise measurement of the atmospheric mass splitting dm^2_32 performed to date. The results are |dm^2_32|=[2.28 - 2.46]x10^-3 eV^2 (68%) and sin^{2}theta_23=0.35-0.65$ (90%) in the normal hierarchy, and |dm^2_32|=[2.32 - 2.53]x10^-3 eV^2 (68%) and sin^{2}theta_23=0.34-0.67 (90%) in the inverted hierarchy. The successor to MINOS in the NOvA era at FNAL, MINOS+, is now collecting data mostly in the 3-10 GeV region, and an analysis of nu_mu disappearance using the first 2.99x10^20 POT of data produced results very consistent with those from MINOS. Future data will further test the standard neutrino oscillation paradigm and allow for improved searches for exotic phenomena including sterile neutrinos, large extra dimensions and non-standard interactions.
The MINOS experiment took data for seven years between May 2005 and April 2012. Since then it has been reborn as the new MINOS+ experiment in the upgraded medium energy NuMI beam and started taking data in September 2013. An update to the MINOS standard oscillations three-flavour disappearance analysis is presented which includes 28% more atmospheric neutrino data. This combined three-flavour analysis calculates an atmospheric parameter best-fit point of $Delta m_{32}^{2}=2.37^{+0.11}_{-0.07} times 10^{-3}$~eV$^{2}$ and $sin^{2}theta_{23}=0.43^{+0.19}_{-0.05}$ for the inverted hierarchy, for which the MINOS fit shows a slight preference. A first look at the new MINOS+ beam data is presented. The new data is consistent with the combined three-flavour analysis. Finally, new MINOS results for the search for sterile neutrinos using neutrino disappearance are shown which cut out a significant amount of the allowed phase space for a sterile neutrino to exist.
We report on $ u_e$ and $bar{ u}_e$ appearance in $ u_mu$ and $bar{ u}_mu$ beams using the full MINOS data sample. The comparison of these $ u_e$ and $bar{ u}_e$ appearance data at a 735 km baseline with $theta_{13}$ measurements by reactor experiments probes $delta$, the $theta_{23}$ octant degeneracy, and the mass hierarchy. This analysis is the first use of this technique and includes the first accelerator long-baseline search for $bar{ u}_murightarrowbar{ u}_e$. Our data disfavor 31% (5%) of the three-parameter space defined by $delta$, the octant of the $theta_{23}$, and the mass hierarchy at the 68% (90%) C.L. We measure a value of 2sin$^2(2theta_{13})$sin$^2(theta_{23})$ that is consistent with reactor experiments.
The MINOS/MINOS+ experiment has recently reported stringent limits on $ u_mu$ disappearance that appear to rule out the 3+1 sterile neutrino model. However, in this paper we wish to point out problems associated with the MINOS/MINOS+ analysis. In particular, we find that MINOS/MINOS+ has either underestimated their systematic errors and/or has obtained evidence for physics beyond the 3-neutrino paradigm. Either case would invalidate the limits on $ u_mu$ disappearance.
Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the $theta_{mu e}$ mixing angle are derived that constitute the most stringent limits to date over five orders of magnitude in the sterile mass-squared splitting $Delta m^2_{41}$, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL$_s$ for $Delta m^2_{41}<5,$eV$^2$.Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL$_s$ for $Delta m^2_{41}$ $<$ 1.2 eV$^2$.
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