Recent

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Recent Results from Super-K
Kate Scholberg, Duke University
June 7, 2005 Delphi, Greece
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OUTLINE
Super-K Status Atmospheric Neutrino Results
-Two-flavor Analyses SK I 'Combined'
Analysis L/E Analysis
New Combined Finer-Binned Analysis
Sterile, Tau Analyses -Three-flavor
Analyses Dominant Mass Scale Analysis
Analysis with Solar Terms The
Future Summary
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Super-K I 1996-2001
- 11,146 inner (ID)/ 1885 outer(OD) PMTs 22.5 kt
fiducial volume - Solar n, atmospheric n, proton
decay results K2K I target
Super-K II 2003-present
- Returned to action with 47 ID coverage
(acrylic shields), full OD - Nearly same
sensitivity as SK I K2K II target - To turn off
October 2005 for full reconstruction
Super-K III 2006-
- Will turn on in April 2006 with full ID PMT
coverage - Ready for T2K off-axis beam from
J-PARC in 2009
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Solar neutrinos with Super-K
See Y. Takeuchi's talk in astrophysics session
for details of solar oscillation results
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SK I Combined 2-Flavor Analysis
hep-ex/0501064
1489 live-days, 100 yr MC, 15,000 neutrino
events
Zenith angle distributions
upgoing
downgoing
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'Standard' Oscillation Analysis
'Pull method', Fogli et al, hep-ph/0206162
Total 180 bins in zenith angle, momentum
fractional change in event rate due to
systematic
systematic parameters (36 based on flux,
x-scn, selection, reconstruction)
observed events in bin
oscillated expectation
estimated uncertainty in ej
MC statistical and systematic uncertainties
Minimizing c2 is equivalent to solving
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Allowed Oscillation Parameters
SK I standard combined analysis
Best Fit Results Dm2 2.1 x 10-3 eV2
sin2(2q) 1.0 (constrained to physical
region) c2min 174.8/177 DOF
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Similar plot with this selected subset (2700
events)
Preliminary
decoherence
decay
best-fit osc (favored by gt3 s)
"the dip"
Seems to be really wiggling!
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Best fit using the high-resolution L/E data sample
Best Fit Results Dm2 2.4 x 10-3 eV2
sin2(2q) 1.0 (constrained to physical
region) c2min 37.9/40 DOF
Improves Dm2 resolution a little
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Results from K2K long-baseline expt
Best Fit Results Dm2 2.8 x 10-3 eV2
sin2(2q) 1.0 (constrained to physical region)
No-oscillation excluded at gt4s
Total 107 beam events observed expect
149.7
Single-ring m-like events
Consistent with SK atmospheric n's
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Zenith angle distributions
Preliminary
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Allowed regions for the various subsamples
370 bin analysis
180 bin analysis
Preliminary
Finer binning for multi-GeV, PC, multi-ring
improves the Dm2 constraint
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1.72 live-years FC/PC 1.67 live-years upmu 60 yr
SK II MC
Super-K II results
Zenith angle distributions
Preliminary
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Super-K II Oscillation Analysis
Preliminary
L/E Analysis
Best Fit Results Dm2 2.6 x 10-3 eV2
sin2(2q) 1.0 (constrained to physical
region) c2min 54.8/40 DOF
370 bin combined analysis
Best Fit Results Dm2 3.1 x 10-3 eV2
sin2(2q) 0.98 (constrained to physical
region) c2min 395.5/367 DOF
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Still thinking in 2D
What flavors are involved in this 2-flavor nm ?
nx disappearance? (assumed to be nm ? nt )

• NOT pure nm ? ne no up-going e-like excess

• NOT pure nm ? nsterile would expect
• up-going NC excess
• angular distortion of high E events

not seen
Can we see tau appearance explicitly?
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Select t-like events (energy, shape, rings,
decay electrons)
2 analyses (likelihood and neural network)
yield consistent answers
MC expectation 79?31 t's
From fit to t-like sample (red hatched)
t's
Neural Network (36efficiency)
osc param
Consistent with (expected) slight excess of
upgoing t's
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First, consider dominant mass difference scale,

(and d0)
m2
m3

m1
atmospheric
m2

solar
m3
m1
Inverted
Normal
In this approximation, oscillation
probabilities described by 3 parameters
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What do the data show?
Multi-GeV e-like events
single-ring
multi-ring
cosq
Basically, no suspicious looking excesses seen...
- use the fine-binned analysis, Poisson-style
likelihood - treat inverted and normal hierarchy
cases separately
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Limits
Normal hierarchy
Best Fit c2min 376.82/368 DOF Dm22.5 x 10-3
eV2,sin2q23 0.5, sin2q13 0.0
Best Fit c2min 376.76/368 DOF Dm22.5 x 10-3
eV2,sin2q23 0.525, sin2q13 0.00625
Inverted hierarchy
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Future upgraded T2K beam (4MW)
and Hyper-K detector
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Limit on admixture of sterile
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