Precision measurement of large mixing angles 12 and 23 Hisakazu Minakata Tokyo Metropolitan...

Precision measurement of large Precision measurement of large mixing angles mixing angles 1212 and and 2323

Hisakazu MinakataHisakazu Minakata

Tokyo Metropolitan UniversityTokyo Metropolitan University

March 9, 2005 IFIC, Universitat de Valencia

The last year: the

oscillatory behavior observed


oscillatory behavior has been seen!

KamLANDKamLAND

K2KK2K

SKSK


Neutrino physics has entered into the new era of precision

measurement


MNS matrix and mass pattern

Neutrino mass hierarchies

• Left: “normal”

• Right: “inverted”

<= solar <= solar

Atm. =>Atm. =>

=Ui i=Ui i

There is the similar structure in quarks

There is the similar structure in quarks


Suppose we have “standard model of flavor mixing” someday …

• Most likely, it unifies quarks and leptons• We may want to test the theory by comparing

mixing angles of quark and lepton sectors• Then, we recognize that our knowledge of 12 i

n quark and lepton sectors are not balanced:

(sin2C) = 1.4% <--> (sin2) ~ 10 %

• Why don’t we try to measure 12 to a comparable accuracy?


Quark-lepton complementarity?

C+solar = 45.1o +/- 2.4o (1)

atm < 53.2o (CL)23

q < 2.5o (CL)23

q +atm = 47.4o +/- 8.3o (CL)

=> 2C and 2solar are

complementary => QLC

=> 2C and 2solar are

complementary => QLC

Thanks to all the solar & KamLAND experiments ==>

Thanks to all the solar & KamLAND experiments ==>

<=Really maximal?

<=Really maximal?

HM-Smirnov, Raidal 04

HM-Smirnov, Raidal 04


Symmetry for maximal 23 and small 13?

• Some people speculate that nearly maximal 23 and small 13 might be due to a symmetry:

• Z2, A4, etc.

• Deviation from maximal 23 and 13 is connected

Grimus et al., Ma, Babu et al., Kubo et al. ……

Grimus et al., Ma, Babu et al., Kubo et al. ……


23 is even worse: present accuracy of determination of mixing angles

Maltoni-Schwetz-Tortola-Valle, NJP 04Maltoni-Schwetz-Tortola-Valle, NJP 04


How to determine these mixing angles accurately?

• I will concentrate on “tomorrow’s item” based on reactor & accelerator

• Entirely new possibilities may exist with neutrino factory and/or beam (?) => interesting question to examine

• I have supplementary slides if you ask questions on how to measure 13


12


The best way, so far, to determine 12

• SNO CC/NC measurement IS the measurement of sin212

Holanda-Smirnov 02

Holanda-Smirnov 02


12; current status

+/-12% error in sin212 (2D)

+/-12% error in sin212 (2D)


Newest vs. next-to-new

est


Where is the most sensitive place to 12 in

the world?

The answer:

In the solar and/or reactor spectra

The answer:

In the solar and/or reactor spectra


Low-E solar spectrum measures sin2212

Nakahata NOON04Nakahata NOON04


measurement of 12 with reactor

HM, Nunokawa, Teves, Zukanovich-Funchal, hep-ph/0407326

HM, Nunokawa, Teves, Zukanovich-Funchal, hep-ph/0407326

SADO =Several-tens of km Antineutrino DetectOr

SADO =Several-tens of km Antineutrino DetectOr


Where is the right place?

• Where is the right place for precision measurement of 12

• What is the most sensitive part of the probability to variation of 12?

• => First oscillation maximum! • => First oscillation maximum!


Can you quantify

the statement

?

YES!YES!


KamLAND vs. SADO; verifying the principle

• Equalize the number of events without oscillation at KL and SADO

• Common systematic error 4 %

• Tuning to OM works !

Other 15 reactors included

Other 15 reactors included


Systematic error

• Modest requirement on systematic error of 4% <= 6.5% of KL

• Feasible if volume error reduced and no spectrum cut at Eprompt=2.6 MeV

• Geo-neutrino “BG” must be taken care of

<== KamLAND<== KamLAND

We take 4%We take 4%


Geo neutrinos in brief• It is expected that

about half of terrestrial heat of 40 TW comes from radioactivity in the earth


Optimal baseline distance

• Without geo- the optimal distance can be as short as ~40km

• With geo- it is 50-70 km

• L < 50 km geo- starts to affect most important part of the spectrum


Definition of 2

We will make comparison with two other definitions of 2

We will make comparison with two other definitions of 2

U:Th ratio fixed; Th = 83% of allU:Th ratio fixed; Th = 83% of all


Where is the site for 12

experiment?

Mt. Komagatake!Mt. Komagatake!


We took SADO at Mt. Komagatake• SADO_single = d

etector at 50-70 km from a NPP at anywhere in the world

• SADO_multi = detector at ~1000 m below peak of Mt. Komagatake, 54 km from KK

For geo- we need to specify the location

For geo- we need to specify the location


Sensitivity for 12; SADO_single

Whole 40 TW comes from radioactivity

Whole 40 TW comes from radioactivity

U:Th ratio fixed; Th = 83% of all

U:Th ratio fixed; Th = 83% of all


Sensitivity for 12; SADO_multi


Stable against changes of L and m2


Does the result

depend on statistical treatment?


Yes, I promised to check stability of the results

We will make comparison with two other definitionsWe will make comparison with two other definitions


Dependence on definition of 2


Can you surpass other

methods?YES definitely!YES definitely!


Solar+KL and SADO are good competitors, but..

• “SADO” has better sensitivity with long-run because tuning L is powerful

2% (1) in sin212 reachable!

2% (1) in sin212 reachable!

Bahcall-Pena-GarayBahcall-Pena-Garay

<= NOW05 Proc.<= NOW05 Proc.


Comparing SADO with the present accuracy


Sensitivity; summary and comparison with solar + KamLAND


Implications of precision measurement of 12

• Besides the ones for particle physics there are various implications:

• Observational solar astrophysics

dominant error of solar flux determination comes from 12!

• Better determination of geo-neutrino flux in KamLAND and others (to reduce error of reactor background)

• Neutrino factory measurement of

• CPT test• ……


23


Does the same method apply

to 23 measurement?

YES and NOYES and NO


Method of tuning to the oscillation maximum for sin2223 measurement

• position of the dip --> m213

• depth of the dip --> sin2223 <= 2 flavor analysis

<= 2 flavor analysis

1% level accuracy expected for sin2(223) (JPARC-SK, LOI)1% level accuracy expected for sin2(223) (JPARC-SK, LOI)


J-PARC vs. SK 80 yrs: sin2(223)

• position of the dip --> m213

• depth of the dip --> sin2223

Kajita, NOON2004Kajita, NOON2004

Better then SK 80 yrs !

Better then SK 80 yrs !


Sensitivity of s223 is affected by Jacobian

and 23 degeneracy (s223)(s2

23)(sin2223)(sin2223)

1st octant assumed1st octant assumed


3 Flavor Effects?

+ 3 corrections prop. to

s132 √(1-sin2223)

m2solar / m2

atm

HM, Sonoyama, Sugiyama, hep-ph/0406073

HM, Sonoyama, Sugiyama, hep-ph/0406073


LBL and reactor experiments help but not so much…

e appearance or reactor do indeed help, but not too much -> 2 flavor result


How to improve

the accuracy of 23?


(1) Resolve 2-3 degeneracy by reactor-LBL experiments

• Rare chance for resolving (2323) degeneracy• If lucky, one may see CP & mass hierarchy

HM-Sugiyama-Yasuda-Inoue-Suekane, hep-ph/0211111HM-Sugiyama-Yasuda-Inoue-Suekane, hep-ph/0211111


Future atmospheric may help

• Not an easy problem for both methods!Concha-Maltoni-Smirnov 04Concha-Maltoni-Smirnov 04


Deviation from maximal 23; already seen?

• If 23 < 45o =>enhancement of e-like events

• Explanation of e-excess at low energy?

Nakayama@Sub-dominant WS, ICRR, Dec.04

Nakayama@Sub-dominant WS, ICRR, Dec.04

Peres-Smirnov 99, 04

Peres-Smirnov 99, 04


Two different results (why?) Concha-Maltoni-Smirnov 04Concha-Maltoni-Smirnov 04 SK (Subdominant

WS, ICRR, Dec.04)

SK (Subdominant WS, ICRR, Dec.04)


Conclusion • 1st oscillation maximum seems to be the b

est place for precision measurement of large mixing angles (12,

• Dedicated reactor 12 experiment can reach the ultimate sensitivity ~2% in sin212

=> balanced accuracies between C and 12

• Implications to: observational solar astrophysics, accurate geo-, CPT test, ….

• LBL disapp. measurement of 3, though accurate for sin2223, suffers from “J” and P-degeneracy issues


We have reproduced their results

insensitive to systematic errors

insensitive to systematic errors


How to measure 13; There are 2 ways

LBL vs. reactorLBL vs. reactor


Reactor measurement of 13

• Independent of , matter effect, 23, 12, solar m2

=> Pure measurement of 13

e disappearance probabilitye disappearance probability


Varying proposals over the globe

A European project approved !

A European project approved !


LBL measurement of 13

JPARC-SK 13 sensitivity; OA2°, 5 years

Very simple form!Very simple form!


Optimal baseline distance

• Without geo- the optimal distance can be as short as ~40km

• With geo- it is 50-60 km

m2 sensitivity continues to be good until ~200 km

Precision measurement of large mixing angles 12 and 23 Hisakazu Minakata Tokyo Metropolitan...

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