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MINOS+ Sterile Neutrino Studies J.Thomas UCL J.Evans (UCL), A.Gavrilenko (W&M), M.Matthis (W&M)A.Sousa(Harvard) UCL

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MINOS+ Precision Measurement ~3000 CC events/year between 4-10GeV (including energy resolution and efficiencies)

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Sterile neutrino search PAC requested update on this

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Different experiments Reactor experiments ( e disappearance): 14 MiniBooNE and LSND ( e appearance): 14 + 24 MINOS (NC and disappearance) 24 + 34 MiniBooNE and LSND, CDHS, CFFR ( dis): 24 MINOS+ ( disappearance) : 24 MINOS+ (NC disappearance) : 24 + 34

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Improvements MINOS+ Monte Carlo used for this analysis – Previous used reweighted LE events Oscillations at the Near Detector are incorporated A complete 4-flavour oscillation formula is used to allow lower reach in m 2 43 – Down to where interference with atmospheric oscillations occurs ( m 2 43 = 2.5x10 -3 eV 2 )

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MINOS+ advantages MINOS+ will have very high statistics – Simulations here use 2 years of neutrinos or 2 years of anti-neutrinos 2 detector experiment – Normalisation measurement at FD rather than shape only (MiniBoone, CDHS, CCFR) – Two baselines : 1km and 735km

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Some Mathematics And helpful assumptions (but these not implemented in simulation)

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Some Maths

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Thought Simplifications m 2 21 dependence can be neglected at this L and E, so 13 is small (set to 0)

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Thought simplifications Reactor anomaly allows 14 < ~9 o, (small) so: End up with: Above m 2 43 of 10 -1 eV 2, sin 2 41 and sin 2 43 ≈0.5 And Probability at FD:

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The limits from last PAC MINOS AND MINOS+

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MINOS MINOS+(old)

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Characteristics of Limits 10 -1 < m 2 34 <1eV 2 : FD in fast oscillation mode and mass squared term averages to ½, so no sensitivity to exact value of m 2 34 m 2 34 > 1eV 2 : Near Detector spectrum affected leading to more structure to the exclusion region m 2 34 > 10eV 2 : ND and FD both see fast oscillations, so comparison cancels sensitivity to the effect

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FD sterile example Both atmospheric and sterile dips apparent here DM2 factor averages to 0.5

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Near Detector Example Systematic error is on ratio of numu to numubar

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MINOS+ θ 24 sin 2 41 ≈sin 2 43 ≈0.5 : FD effect Atmospheric analysis assumed correct! ND starts fast oscillation too ND starts to see effect

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Bottom Line anti-neutrinosneutrinos

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Summary More careful job results in much larger reach NC additional analysis not yet complete but improvement expected between 10 -2 eV 2 and 10 -3 eV 2. MINOS+ has a world-beating sensitivity to this sterile search for both neutrinos and antineutrinos over large range of mass splitting

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