1 Latest CC analysis developments New selection efficiencies: –Based on C++ reco + PDFs rather than old (Fortran+reco_minos) cuts –Attempt to optimise PID cut 5 year plan: –Sensitivities calculated year by year Discrimination between osc. models –Standard oscillations vs nu decoherence D. A. Petyt May ‘03

2 PDF-based CC/NC separation Idea is to replace old cut-based efficiencies with more modern/realistic values New selection uses likelihood method described at South Carolina Currently using simplest implementation – 3  1D pdfs. CC NC

3 PID results (from SC) CC NC Cut on the PID parameter to distinguish between CC/NC – the precise value of this cut will be a trade-off between purity and efficiency

4 Sample ‘CC-like’ distributions Visible energy (0-30 GeV) PID>-0.5 PID>0.1PID>-0.1 PID>-0.3 Key Perfect ID CC NC

5 Optimising the PID cut Many possible ways to do this. The method I chose attempts to optimise the oscillation signal by examining –Overall significance of the effect (units of  –Size of the dip at oscillation maximum (units of  –Evidence for a rise at low energy (units of  Optimisation will depend on how well NC background is understood. –I assume that I can make a full subtraction of the mis-identified NC events, but assign an additional error that is proportional to the number of NC events in each bin of E vis Optimisation will be dependent on  m 2. –The plots I show here are for  m 2 = eV 2 –Have looked at  m 2 = eV 2. Optimum cut seems similar but statistical errors are large

6 PID cut =-0.5,  m 2 =0.0025

7 Finding the optimum Define a quality factor that is the product of these three quantities. Optimum selection between –0.1<PID<0.1 Optimium PID cut increases with increasing uncertainty on NC background I chose PID>–0.1 – try to maximise CC efficiency

8 CC selection efficiencies as a fn. of true E and y True neutrino energy (0-30 GeV)

9 NC inefficiencies Factor of 3 lower than previous cuts True neutrino energy (0-30 GeV)

10 Comparison of old and new efficiencies Unoscillated CC spectra – No NC background

11 5 year plan I have taken the numbers for the ‘default’ 5 year plan that was sent around several weeks ago and have calculated year-by-year sensitivities with the following inputs: –le and semi-me,he beams from NuMI-L-783 –Efficiencies based on PID cut –Assume “VLE=LE” –Ignore anti-neutrino running (don’t know fluxes) –Statistical errors only – recommendations for beam (and other) systematics? This is a literal interpretation of 5 yr plan: –Do we want more generic N  p.o.t plots instead/as well? Some of these were shown at SC.

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17 Discriminating against exotic models Several exotic models of neutrino mixing exist which can provide a reasonable fit to the SK  -like data. Nu decay is ruled out by SK due to the non-observation of   sterile. Nu decoherence, which does not involve active  sterile transitions, is still a possibility.

18 Oscillations vs decoherence This analysis motivated by hep-ph/ , which shows how well SK+K2K data can discriminate against the decoherence hypothesis General survival probability (osc+decoherence): –Comments: Pure oscillations:    Pure decoherence:  m 2  In pure decoherence scenario: P   I have performed a fit to these 3 parameters, assuming standard oscillations with  m 2 = eV 2 and compared the results to those obtained for SK/K2K in hep-ph/

19 Fit result – 5 year plan, year 1 Shown are the three 2D projections of the 3- dimensional allowed volume SK allows  m 2  0 at 99% C.L. MINOS does not

20 Fit result – 5 year plan, year 5

21 Constraint on decoherence parameter 

22 Plots for 5yr plan/response to PAC questions Two basic questions: –What plots are required? –What inputs (beams, systematics…) 5 year plan plots: –Specific run plans and/or generic sensitivity vs POT plots? –Low  m 2 scenario (using VLE beam, if available)? PAC questions: –Q1 – ‘5 sigma dip’: precise definition? Easy to do but implies low p.o.t. even for low  m 2 –Q2,3 – ‘95% exclusion of nu decay/3  preference of osc. over decay’:   between best-fit osc and best-fit decay? Probably also implies low p.o.t. (see decoherence results) Inputs: –More up-to-date spectra (esp. le) available? –Recommended systematic uncertainties on beam flux? –Treatment of mis-identified NC: assume perfect subtraction or full subtraction with some error. What error?