Toward realistic evaluation of the T2KK physics potential What’s that ? Preliminary KEKPH0712 @ KEK Dec.12, 2007 N.Okamura (KEK)

What’s the T2KK ?? There are 6 parameters in the “neutrino oscillation” Unknown parameters The sign of the larger mass-squared difference Value of the CP phase (MNS) Value of the 13  Reactor exp. will measure The correct value of 23 (larger or smaller than 45o) T2KK = Tokai-to-Kamioka exp. (T2K, will start 2009) + far detector in Korea (L~1000km) T2K neutrino beam will reach Korea, automatically.

Digest of our previous work 5x1021POT exposure include the “reactor exp.” Volume 22.5 kton/100Kton (SK/Kr) OAB : 3.0/0.5 (SK/Kr) essence of T2KK 2 detectors, 300km + 1000km matter effect helps to determine 2 of 3 (1acc.,2detector) exist sin22RCT=0.1, MNS=0.0 2 = 22 (input : normal) mass hierarchy CP phase 1 ~ 30o w/o anti-neutrino Detail of T2KK K.Hagiwara, K.Senda, NO, PLB637 266 (2006) PRD76 093002 (2007) K.Hagiwara, NO, hep-ph/0611058 and ref. there in

motivation We study the robustness of the results, previous work this work CC CCQE only CCQE + -Res. NC no 0 background binning energy Neutrino Reconstructed  (SK/Kr) 2.8/3.0 (g/cm3) 2.6/3.0 (g/cm3) error of  3% 6% miss ID (e) 1%(1%) efficiency (e) 100% 90%(5%) efficiency () 100%(-1%) resolution include We study the robustness of the results, best combination, hierarchy (2), CP phase (MNS).

CC Reconstruction Resolution Fit functions

event selection (106):mono. energy only one  (e) CCQE Res. 20000 15000 10000 5000 25000 E = 1GeV (106):mono. energy 400MeV Erec total (CC) : 728702 CCQE : 390620 resonance : 129340 only one  (e) |p| > 200MeV no high energy +/- |p| < 200MeV no high energy  |p| < 30MeV no 0/Ks/K+/K- nuance Ver.3.504 (Apr/25,2006) D. Casper (UC.Irvine)

resolution -like e-like p %  1.8o 3.0o Detector has the resolution for momentum and the angle. Dilute the reconstruction energy obtained from the momentum of e, and scatter angle. e :E=2GeV -like e-like p %  1.8o 3.0o (from SK)

fit functions For E  Erec conversion : fit function CCQE Res. Sum of the 3 gauss functions for CCQE, 3 or 4 gauss functions for resonance mode. Cover region : Erec > 0.4GeV for E=0.3 ~ 6.0GeV Erec < 0.4GeV rapid oscillation, small , etc. not include E > 6.0GeV  no beam flux

NC 0 event (for e-like background)

event selection only one 0 no- / e no high energy +/- |p| < 200MeV no high energy  |p| < 30MeV no Ks/K+/K- 0.5 OAB 480 event at 0.2-0.4GeV 300 event at 0.4-0.6GeV 0 distribution after event selection

0 event cut 0 () sometimes seems an “e-like” events. energy ratio (E1>E2) E2 /(E1+E2) < 0.2 : 100% missed opening angle (cos) cos > cos17o = 0.956

Pe/(|p|) Pe/ |p|(GeV)

Event Numbers

events at Korea e  e 0 dominates at low energy (Erec<1GeV) CCQE event is larger than the others Erec=0.4-2.8GeV  Almost CCQE Resonant mode is comparable at low energy Erec=0.4-5.0GeV  sin22RCT=0.1, MNS=0.0

events at SK e  e CCQE event is dominant Erec=0.4-1.2GeV Event from resonance is smaller. Erec=0.4-5.0GeV  sin22RCT=0.1, MNS=0.0

2 Best combination Effect mass hierarchy CP phase (MNS) 0, resonance mode

input and systematic Solar Atmospheric matter density (uncertainty 6%) sin22 = 0.83 0.07, m2 = (8.2  0.6) 10-5 eV2 Atmospheric sin22 = 1.000.96, m2 = 2.5 10-3 eV2 matter density (uncertainty 6%)  = 2.6 / 3.0 (g/cm3) (SK/Korea) Systematic flux normalization (3%) (each flavor to SK/Korea) fiducial volume (3%) (SK / Korea) CCQE  (3%) ( / ) Resonance (10%) ( / ) 0 (30%) ( = ) efficiency (100-1%/905%) ( /e) miss PID (11%) #total:26

2 -rule of the game- statistics systematic input expected error of reactor exp. Reactor experiments helps T2KK to solve the degeneracy.

Condition fiducial volume exposure base-line and off-axis SK : 22.5 kton Korea : 100 kton exposure 5 x 1021 POT no anti-neutrino phase base-line and off-axis SK: L=295km with =2.5o or 3.0o KR: L=1000-1200 km with =(0.5o ~ 3.0o) / 0.5o step Previous results for mass hierarchy 3.0@SK and 0.5@Kr (L=1000km) is the best combination 2 = 22, input : normal, sin22rct = 0.10, MNS=0.0 2 = 21, input : inverted, sin22rct = 0.10, MNS=0.0

Results Best combination is still SK(3.0) and Kr(0.5) L=1000 2=13 (input : normal) 2=11 (input : inverted) contribution to 2 (normal) Previous Setup 22.9 matter density (SK) 0.5 resonance 2.7 density error -0.6 miss ID (-e) -1.0 reconstruction -2.3 efficiency (e) -2.3 0 background -6.5 total 13.4 3.0@SK normal normal positive 3.0@SK 2.5@SK negative inverted inverted sin22RCT=0.1, MNS=0.0

Contour (input : normal) 25 9 sin22rct ~ 0.05 MNS~ 30o sin22rct ~ 0.09 MNS~ 45o 9 25

summary hierarchy CP phase CC ( res.) positive negative NC(0) The others, reconstruction, matter profile, and so on, do not change the results drastically. “3.0 at SK and 0.5 at 1000km” is still the best. 2 23  13 (input : normal) 21  11 (input : inverted) MNS 30o  45o (3 2)

Thank you for your attention