1. 1 A study to clarify important systematic errors A.K.Ichikawa, Kyoto univ. We have just started not to be in a time blind with construction works. Activity members come from KEK, Kyoto univ and Tokyo univ.

2. 2 Hiraide study in 2004 http://www-he.scphys.kyoto-u.ac.jp/member/hiraide/t2k/index.html Systematic shifts on (sin 2 2  ,  m 23 2 ) are evaluated with following systematic errors. –Flux normalization uncertainty (10%) –Non-QE ratio uncertainty (20%) –Energy scale uncertainty (4%) –Spectrum shape uncertainty (FLUKA/MARS) –Spectrum width uncertainty (10%)

3. 3 Systematic shift norm shape esk nqe stat. width  (sin 2 2  ) (m2)(m2) shape nqe width norm esk stat. Various systematic shifts are shown as a function of true  m 2. Dashed lines indicate the size of statistical error. OA2.5deg K.Hiraide MINOS 90%

4. 4 This was a very instructive study. Direct reduction of above systematic errors is very important. Indirect reduction of systematic errors by cancellation btw. near and far observation is not evaluated. Near to Far Extrapolation method should be studied. A new method may be useful if that is found to be robust against systematic uncertainty. –Default : Far/Near ratio –Matrix in (E far, E near ) plane. –Using parent’s(= ,K) (p,  ) distribution Some of the systematic errors is not evaluated. (e.g. beam related ones.)

5. 5 Cancellation of syst error on N 11exp N SK MC (f) ∝ N KT MC (f) N 11exp (f) From K2K

6. 6 Contribution of syst. errors on spectrum Total Spec.nQE/QESpec.+nQE/QE F/N  SK SK Escale From K2K

7. 7 K2K-II e appearance search Error on backgrounds from  NC1  0 /CC ratio +6%,-7% NC/CC ratio(non-NC1  0 ) +-3%  0 energy spectrum +-8% coherent  0 model +3%,-10%  0 mass cut +19%,-17% water properties+-6% neutrino flux at SK+-6% non-QE/QE ratio+-1% detector efficiency+-6% single electron selection+7%, -8% Total+39%,-24% * Super-K intrinsic

8. 8 Short term goal of this study Find the best near to far extrapolation method –The best one would varies depending on statistics and information from NA61 and ND measurements. –Can ND mesurements constrain hadron production uncertainty when there is uncertainty on netrino interaction? Make oscillation analysis tool for T2K based on the K2K method. –See next slide. Clarify the importance of following systematic errors as a function of statistics –Hadron production Compare GFLUKA, MARS and FLUKA2007 Getting reasonable error matrix on flux by assuming reasonable uncertainty in (p,  ) distribution After NA61 results come, this will be replaced. –Beamline origin (misalignment etc.) –Neutrino interaction Energy dependent non-QE/CCQE ratio, NC/CC ratio – Super-K intrinsic energy scale and normalization (comes from FV, PID etc.) For e appearance, statistical and Super-K intrinsic error would be dominant. Still update of p.7 table with T2K off-axis flux is important to confirm this.

9. 9 Likelihood Normalization term Systematic parameter constraint term Shape term for FCFV 1R  From K2K

10. 10 T2K Near to Far extrapolation Matrix K.Sakashita Robustness against the hadron production uncertainty will be checked. E (Super-K) v.s. E (on-axis) will be made, too. E (Off-axis ND280) E (Super-K)