Constraint on q 13 from the Super-Kamiokande atmospheric neutrino data

1. Constraint on q13 from the Super-Kamiokande atmospheric neutrino data Kimihiro Okumura(ICRR) for the Super-Kamiokande collaboration December 9, 2004 RCCN workshop @ Kashiwa ICRR

2. M. Shiozawa’s talk S. Nakayama’s talk Outline • In this talk, 3-flavor oscillation analysis results, assuming one mass scale dominance (Dm122=0), will be presented. • We will have two more talks on: • Effect of solar oscillation term (Dm122≠0) in atmospheric neutrino sample • Future possibilities

3. Fully Contained (En ~1GeV, nenm) Partially Contained (En ~10GeV, nm) Stopping m (En ~10GeV, nm) Through-going m(En ~100GeV, nm) Observation of Atmospheric Neutrinos in Super-Kamiokande Event classification Water Cherenkov detector • 1000 m underground • 50,000 ton (22,500 ton fid.) • 11,146 20 inch PMTs (SK-I) • 1,885 anti-counter PMTs

4. Neutrino oscillation with Dm12=0 six parameters (Dm122,Dm232, q12, q23, q13,d) : Weak eigenstates Neutrino Mixing : Mass eigenstates Mixing Matrix : cij=cosqijsij=sinqij In the approximation of Dm122=0 expressed with three parameters (Dm232, q23, q13) (We know Dm122~8.3×10-5eV2 ) 3-flavor oscillation with Dm122=0 in case of vacuum oscillation q13=0 two parameters (Dm232, q23) 2-flavor oscillation (nm↔nt)

5. 1+multi-ring, e-like, 2.5 - 5 GeV Electron appearance s213=0.05 s213=0.00 null oscillation Search for non-zero q13 constraint on q13 given by reacter experiment; sin2q13<0.05 oscillation w/ matter vacuum oscillation 0.45 Mtonyr (Super-K 20yrs) matter effect cosQ En(GeV) Electron appearance expected in the 2 -10GeV upward going events.

6. SuperK-I atmosheric neutrino data CC nm CC ne • 1489day FC+PC + 1646day upward going muon data • special sample: Multi-Ring electron to increase multi-GeV ne sensitivity

7. Selection criteria for Multi-GeV Multi-Rring electrons We used Likelihood method to discriminate multi-G multi-R electrons; • FC, Evis>1.33GeV • Most energetic ring is electron-like • Log(electron likelihood) > 0 • defined by following variables; • PID likelihood • Momemtum fraction of most energetic ring • Number of decay-electrons • Distance btw decay-e and primary vertex • considering energy dependence

8. Total electron-likelihood select • ne CC events are enhanced by Likelihood cut • 52% → 74% (percentage %)

9. Binning for 3flavor analysis zenith angle 10 bin 1GeV Up-stop 10GeV PC-thru PC-stop multi-R muon single-R muon multi-R electron single-R electron Up-thru P All zenith angle is 10bins 37 momentum bins x 10 zenith bins = 370 bins in total

10. c2 definition for 3-flavor analysis • c2 was calculated with Poisson probability • Effect of systematic error was considered for calculating expectation • Systematic error terms were obtained by solving linear equation : Mij×ej=vj • (G.L.Gogli et al. hep-ph/0206162)

11. List of systematic errors • Combined • overall normalization • relative norm. FC/PC • relative norm. upstop/upthru • Neutrino flux • nm/ne below 5GeV • nm/ne above 5GeV • anti-ne/ne below 10GeV • anti-ne/ne above 10GeV • anti-nm/nm below 10GeV • anti-nm/nm above 10GeV • UP/DOWN ratio • Horizontal-vertical in FC/PC • Neutrino flight length • Energy spectrum • K/pi ratio • Sample-by-sample normalization (FC multi-GeV m) • Sample-by-sample normalization (PC and upstop) • Neutrino interactions • QE • Single-p production • DIS • DIS Bodek • Coherent p production • NC/CC • Low energy QE • Axial vector mass (MA) • Hadron simulator • Nuclear effect • SK • Event selection • FC reduction • PC reduction • Upmu efficiency • Upmu 1.6GeV cut • Flasher BG • Cosmic mu BG • Event reconstruction • Ring-counting • Single-R PID • Multi-R PID • Energy calibration • Up/down asymmetry of energy • Others • Tau • 3flavor analysis • Upthru BG in horizontal bin • Upstop BG in horizontal bin • Non neCC in multi-G single-R electron • Non neCC in multi-G multi-R electron • Normalization of multi-R electron Total number of errors: 44

12. P(nene) P(nenm) Log10(E GeV) Analysis details Matter density • 100yr Monte Carlo data was generated for expectation • 4 step constant function was used for matter density in Earth • Averaging technique of oscillation probability was used to compensate small MC statistics • c2 was calculated in oscillation parameter space of (Dm2, sin2q23, sin2q13) Earth radius (km) averaged Dm2=2.0x10-3 eV2 sin2q23=0.5 sin2q13=0.05 cosqzenith=-0.6

13. Best-fit zenith angle distributions CC nm CC ne Null oscillation c2min/ndf = 376.82/368 @(2.5x10-3, 0.5, 0.0)

14. multi-GeV electrons Zenith angle UP/DOWN asymmetry single-R electron multi-R electron No significant excess due to matter effect was seen in upward-going multi-GeV electron sample

15. Allowed region by 3 flavor analysis Normal hierarchy c2min/ndf = 376.82/368 @(2.5x10-3, 0.5, 0.0) sin2q13 sin2q13<0.14 was allowed in 90% C.L. with SK data only sin2q23

16. Allowed region by 3 flavor analysis Normal hierarchy Dm2 (eV2) sin2q23 sin2q13 0.36<sin2q23<0.65 was allowed in 90% C.L.

17. Normal (Dm2>0) or inverse (Dm2<0) mass hierarchy ? Normal Inverse n2 n3 • Matter effect is different btwn normal / inverse mass hierarchy: • Basically, water Cherenkov detector cannot discriminate neutrino/anti-neutrino event-by-event basis, but small effect can be obtained in multi-GeV electron sample due to the difference of cross section, etc.. n1 Dm2>0 Dm2<0 n2 n3 n1

18. Normal vs Inverse hierarchy Normal (Dm2>0) c2min/ndf = 376.82/368 @(2.5x10-3, 0.5, 0.0) Inverse (Dm2<0) c2min/ndf = 376.76/368 @(2.5x10-3, 0.525, 0.00625)

19. Summary • 3-flavor oscillation analysis with Dm122=0 assumption was performed using SK-I combined (FC+PC+Upm) dataset. • No significance excess in upward-going multi-GeV electron was seen • With this oscillation scheme and normal hierarchy assumption, 90% C.L. allowed region was obtained ; • sin2q13<0.14 • 0.36<sin2q23<0.65 • Both normal and inverse mass hierarchy hypothesis are consistent with Super-K data

20. End