Constraint on q 13 from the Super-Kamiokande atmospheric neutrino data
description
Transcript of Constraint on q 13 from the Super-Kamiokande atmospheric neutrino data
Constraint on 13 from the Super-Kamiokande atmospheric neutrino data
Kimihiro Okumura (ICRR)
for the Super-Kamiokande collaboration
December 9, 2004
RCCN workshop @ Kashiwa ICRR
Outline
In this talk, 3-flavor oscillation analysis results, assuming one mass scale dominance (m12
2=0), will be presented.
We will have two more talks on: Effect of solar oscillation term (m12
2≠0) in atmospheric neutrino sample
Future possibilities M. Shiozawa’s talk
S. Nakayama’s talk
Observation of Atmospheric Neutrinos in Super-Kamiokande
Fully Contained (E ~1GeV, e )
Stopping (E~10GeV, )
Partially Contained (E ~10GeV, )
Through-going (E~100GeV, )
1000 m underground 50,000 ton (22,500 ton fid.) 11,146 20 inch PMTs (SK-I) 1,885 anti-counter PMTs
Water Cherenkov detector Event classification
Neutrino oscillation with m12=0
iiU Neutrino Mixing : Weak eigenstates
: Mass eigenstates
100
0
0
0
010
0
0
0
001
1212
1212
1313
1313
2323
2323
111
111
321
cs
sc
ces
esc
cs
sc
UUU
UUU
UUU
Ui
ieee
cij=cosij sij=sinijMixing Matrix :
i
E
LmP e
22
132
232 27.1
sin2sinsin)(
E
LmP ee
22
132 27.1
sin2sin1)(
E
LmP
22
232
132
232
132 27.1
sin)sincos1(sincos41)(
In the approximation ofm2=0
(We know m122~8.3×10-5eV2 )
expressed with three parameters (m23
2, 23, 13)
13=0
E
LmP
22
232 27.1
sin2sin1)(
0)( eP
2-flavor oscillation (↔
six parameters (m12
2, m232,
12, 23, 13,)
in case of vacuum oscillation
3-flavor oscillation
with m122=0
two parameters (m23
2, 23)
Search for non-zero 13
Electron appearance expected in the 2 -10GeV
upward going events.
E
LmP m
e
22
132
232 27.1
sin2sinsin)(
E(GeV)
cos
)( eP
matter effect
vacuum oscillation
s213=0.05 s213=0.00 null oscillation
Electron appearance
1+multi-ring, e-like, 2.5 - 5 GeV
0.45 Mtonyr
(Super-K 20yrs)
)( eP oscillation w/ matter
constraint on 13 given by reacter experiment; sin213<0.05
SuperK-I atmosheric neutrino data
special sample: Multi-Ring electron to increase multi-GeV e sensitivity
CC e CC
1489day FC+PC + 1646day upward going muon data
Selection criteria for Multi-GeV Multi-Rring electrons
• FC, Evis>1.33GeV• Most energetic ring is electron-like• Log(electron likelihood) > 0 defined by following variables;
1. PID likelihood2. Momemtum fraction of most energetic ring3. Number of decay-electrons4. Distance btw decay-e and primary vertex considering energy dependence
We used Likelihood method to discriminate multi-G multi-R electrons;
Total electron-likelihood
CCeCC
NC
w/ L cut w/o L cut
e CC 73.5 52.0
CC 11.4 26.7
NC 15.1 21.3
e CC events are enhanced by Likelihood cut
52% → 74%
(percentage %)
select
Binning for 3flavor analysis
single-R muon
multi-R muon
Up-stop
Up-thru
All zenith angle is 10bins 37 momentum bins x 10 zenith bins = 370 bins in total
multi-R electron
single-R electron
PC-stop PC-thru
1GeV
10GeV
zenith angle 10 bin
PP
2 definition for 3-flavor analysis
errorsystematicofsigma
tcoefficienerrorsystematicf
termerrorsystematic
eventsectedofN
binnthineventsobservedofN
fN
NNNfN
i
ni
i
n
nobs
i in
i
ni
n
nobsn
obsnobs
i
ni
n i
ii
1:
:
:
exp:#
:#
) 1(
ln2) 1(2
exp
2
exp
exp2
n
ni
nnobsij
in
nj
ni
nobs fNNfffN exp
2j2
2mini
2
...))(1( 1
@ 0
• 2 was calculated with Poisson probability
• Effect of systematic error was considered for calculating expectation
• Systematic error terms were obtained by solving linear equation : Mij
×j=vj
(G.L.Gogli et al. hep-ph/0206162)
a. Combined overall normalization relative norm. FC/PC relative norm. upstop/upthru
b. Neutrino flux• /e below 5GeV• /e above 5GeV• anti-e/e below 10GeV• anti-e/e above 10GeV• anti-/ below 10GeV• anti-/ 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 ) Sample-by-sample normalization (PC and upstop)
c. Neutrino interactions• QE• Single-production• DIS• DIS Bodek• Coherent production• NC/CC• Low energy QE• Axial vector mass (MA)• Hadron simulator• Nuclear effect
d. SK 1. Event selection
FC reduction PC reduction Upmu efficiency Upmu 1.6GeV cut Flasher BG Cosmic mu BG
2. Event reconstruction Ring-counting Single-R PID Multi-R PID Energy calibration Up/down asymmetry of energy
3. Othersa. Tau
4. 3flavor analysis Upthru BG in horizontal bin Upstop BG in horizontal bin Non eCC in multi-G single-R electron Non eCC in multi-G multi-R electron Normalization of multi-R electron
List of systematic errors
Total number of errors: 44
Analysis details
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
2 was calculated in oscillation parameter space of (m2, sin223, sin213)
Log10(E GeV)
P(e)
P(ee)
Earth radius (km)
Mat
ter
dens
ity
averaged
m2=2.0x10-3 eV2
sin223=0.5 sin213=0.05
coszenith=-0.6
Best-fit zenith angle distributions
Null oscillation 2min/ndf = 376.82/368 @(2.5x10-3, 0.5, 0.0)
CC e CC
multi-GeV electronsUP/DOWN asymmetryZenith angle
No significant excess due to matter effect was seen in upward-going multi-GeV electron sample
single-R electron
multi-R electron
Allowed region by 3 flavor analysis
2min/ndf = 376.82/368 @(2.5x10-3, 0.5, 0.0)
sin
2
sin2
Normal hierarchy
sin213<0.14 was allowed in 90% C.L. with SK data only
Allowed region by 3 flavor analysis
sin2 sin2
m2
(eV
2)
Normal hierarchy
0.36<sin223<0.65 was allowed in 90% C.L.
Normal (m2>0) or inverse (m2<0) mass hierarchy ?
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..
3
2
13
2
1m2>0
m2<0
Normal Inverse
neutrino anti-neutrino
m2>0 enhanced suppressed
m2<0 suppressed enhanced
Normal vs Inverse hierarchy
Normal (m2>0)
Inverse (m2<0)
2min/ndf = 376.82/368 @(2.5x10-3, 0.5, 0.0)
2min/ndf = 376.76/368 @(2.5x10-3, 0.525, 0.00625)
Summary
3-flavor oscillation analysis with m122=0 assumption was
performed using SK-I combined (FC+PC+Up) dataset. No significance excess in upward-going multi-GeV electr
on was seen With this oscillation scheme and normal hierarchy assum
ption, 90% C.L. allowed region was obtained ; sin213<0.14
0.36<sin223<0.65
Both normal and inverse mass hierarchy hypothesis are consistent with Super-K data
End