Takaaki Kajita ICRR, Univ. of Tokyo Nufact05, Frascati, June 2005

◆ New solar neutrino data from SNO and neutrino oscillations ◆ New atmospheric neutrino data from Super-K and neutrino oscillations

SNO collab nucl-ex/ Also, M.Chen ENTApP2005

History of SNO Pure D 2 O Salt 3 He Counters NOW ? (1)  e+ +d  e - +p+p (CC) (also compared with SK +e  +e) (2)  x d  x pn, n+d  t+  (6.25MeV) (NC) & e +d  e - +p+p (CC) (3)  x +d  x +p+n, n+ 35 Cl  36 Cl+  ’s(  8.6MeV) (NC) & e +d  e - +p+p (CC) New! (4) New! Same as (3), but with improved stat. and syst. (1) (2) (3) (4)

391-day salt phase flux measurements  CC ( e ) = 1.68 (stat.) (syst.) × 10 6 cm −2 s −1  ES ( x ) = 2.35 (stat.) (syst.) × 10 6 cm −2 s −1  NC ( x ) = 4.94 (stat.) (syst.) × 10 6 cm −2 s − − − − − − −0.34 vertex cos  sun ~ isotropy ※ The previous number based on 254days salt data was: 0.306±0.026± w/o 8 B energy constraint

e and (  +  ) fluxes e and (  +  ) fluxes SSM 68%CL SNO NC 68%CL SNO CC 68%CL SNO CC 68%CL SNO ES 68%CL SNO ES 68%CL SK ES 68%CL SK ES 68%CL All the data are consistently explained within the standard oscillation

Comparison of results from SNO-D 2 O phase and SNO-salt phase Pure D 2 O Salt phase CC spectrum constrained Un-constrained CC NC

New day-night results from the salt-phase A NC =0 not required, E spectrum unconstrained: A CC = ±0.074±0.053 A NC =0 required, E spectrum constrained: A CC = ±0.058±0.027 A CC (%) A NC (%) A = 2(  N -  D ) / (  N +  D ) LMA prediction = +2.7% Combined result with the pure D 2 O A CC (=0.070± ): A CC (phase-I+II)=+0.037±0.040 Combined result with the Super-K A ES (=0.021± ) assuming the dilution factor due to  and  fluxes is 1.55: A CC (SNO+SK)=+0.035±0.027  consistent with the LMA prediction

Oscillation Analysis with 391-day Salt global solar with new SNO salt global solar plus latest KamLAND and new SNO salt SNO collab nucl-ex/ Also many other analyses Best fit  12 =33.9deg. (previous = 32.5deg)

New SK-II data Signal (stat.) 7.0 – 20.0 MeV 622 days SK-II Preliminary SK-II Flux = 2.36 ±0.06 (stat.) x 10 6 /cm 2 /sec (SK-I flux: 2.35  0.02(stat.)  0.08(sys.) ) Ready to start the physics analysis with the SK-II data. SK collab. Y.Takeuchi WIN05 = /-0.049(stat.) (sys.) A DN = (Day-Night) (Day+Night)/2 (SK-I D-N asymmetry: / ) Preliminary

SK-I atmospheric neutrino analysis with finer binning. Solar term effect and sin 2  23 (SK-I) Detection of CC  interactions (SK-I) SK-II data and 2 flavor oscillation analysis SK-II L/E analysis (preliminary) SK collab. K.Scholberg, WIN05

SK-I atm analysis with finer binning In the previous atmospheric neutrino analyses in Super-K, Zenith-angle analysis  good for sin 2 2  L/E analysis  good for  m 2 Single analysis that gives best sin 2 2  and  m 2 ? Full oscillation 1/2 osci. Important energy range to see the oscillation dip = multi-GeV Finer energy bins for multi-GeV events Important energy range to see the oscillation dip = multi-GeV Finer energy bins for multi-GeV events 180  370 bins in (p, zenith, ev-type)

Expected sensitivities (MC 5yr exposure) Zenith- 180bin Zenith-370bin 2 2 ,  m 2 ) truth = (1.00, 2.5×10 -3 ) Zenith-370bin

Allowed region from the finer binning analysis Old zenith-angle analysis L/E analysis 90% CL allowed region: sin 2 2  > <  m 2 < 3.0×10 -3 eV 2 90% CL allowed region: sin 2 2  > <  m 2 < 3.0×10 -3 eV 2 (preliminary) Also consistent with all the other data Kam Soudan-2 K2K MACRO

s 2 2  12 =0.825  m 2 12 =8.3×10 -5  m 2 23 =2.5×10 -3 sin 2  13 =0 Because of the LMA solution, atmospheric neutrinos should also oscillate by (  12,  m 12 2 ). Oscillation probability is different between s 2  23 =0.4 and 0.6  discrimination between  23 >  /4 and <  /4 might be possible by studying low energy atmospheric e and  events. s 2  23 =0.4 =0.5 =0.6 However, due to the cancellation between   e and e  , the change in the e flux is small. Peres & Smirnov NPB 680 (2004) 479 Solar term effect to atmospheric Solar term effect to atmospheric

Constraint on sin 2  23 with and without the solar terms hep-ph/ found the  2 minimum at sin 2  23 =0.46 (Also E.Lisi this conference) …We need to understand the reason for this difference. w/o solar terms w/ solar terms Still (almost) maximum mixing is most favored. (preliminary)

Search for CC  events CC  events    hadrons ● Many hadrons ．．．． (But no big difference with other (NC) events ． ) BAD  - likelihood analysis ● Upward going only GOOD Zenith angle Only ～ 1.0 CC  FC events/kton ・ yr (BG (other events) ～ 130 ev./kton ・ yr) Only ～ 1.0 CC  FC events/kton ・ yr (BG (other events) ～ 130 ev./kton ・ yr) hadrons CC  MC

Tau likelihood (or NN) analysis Selection Criteria multi-GeV, multi-ring most energetic ring : e-like log(likelihood) > 0 or NN > 0.5 total visible energy number of ring candidates distance between interaction point and decay-e point max(P  ) clustered sphericity log(sphericity) downward DATA BG-MC tau-MC Cut  likelihood upward  MC) DATA BG-MC tau-MC Cut  likelihood Number of events

Zenith angle dist. and fit results (prelim., new) Likelihood analysisNN analysis , e, & NC background Data ×1.82  MC ×1.93  MC cos  zenith Number of events 145±48(stat) +9 / -36 (osc. para. uncertainty) 152±47(stat) +12 / -27 (osc. para. uncertainty) 79±31(syst) Fitted # of  events Expected # of  events

SK-II atmospheric neutrino data FC&PC: 627days, Up-going muons: 609days e-like  -like

Allowed osc. parameter region (preliminary) SK-II data are consistent with the SK-I data. (preliminary) (SK-I + II combined analysis: next stage)

SK-II L/E analysis L/E analysis was carried out for the SK-II data with the identical selection criteria as those in SK-I. (preliminary) SK-II SK-I Osc. Decay Decoh. Consistent with SK-I. Oscillation still gives the best fit to the data. Consistent with SK-I. Oscillation still gives the best fit to the data.

Allowed parameter region based on the SK-II L/E analysis (preliminary) SK-II SK-I SK-II data are consistent with the SK-I data. (SK-I + II combined analysis: next stage)

New SNO salt result New SK(-II) atmospheric neutrino results No surprise But our knowledge on neutrino masses and mixing angles are improving.

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Oscillation Analysis latest SAGE, final Gallex/GNO, final Cl SK 1496-day zenith-spectrum SNO-I (pure D 2 O) summed spectra day+night (CC+ES+NC+backgrounds) SNO-II (391-day salt) extracted CC spectra (day+night), NC and ES fluxes (day+night) KamLAND 766 ton-yr results Input:

Binning for new analysis (=same binning as 3 flavor analysis) E Single- Ring  Multi- Ring  Up-stop Up-through 37 momentum bins x 10 zenith bins = 370 bins in total Multi- Ring e Single- Ring e PC- stop PC- through Same as old analysis finer binning Sample used in 3-flavor Fewer number of events per bin Poisson statistics to calculate  2 Multi- GeV Sub- GeV CC e CC 