Download - New Views on the Problem of CP Violation
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New Views on the New Views on the Problem of CP ViolationProblem of CP Violation
H. MinakataH. Minakata
Tokyo Metropolitan University Tokyo Metropolitan University (TMU)(TMU)
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Why do we look for leptonic CP violation?
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Lepton-quark correspondence
• Quantum anomaly tells us that leptons and quarks are related with each other in a deeper level => we want to know if leptonic KM phase is unsuppressed
“lepton-quark correspondence” in the spirit of Nagoya model (Sakata et al., ‘60th) Shoichi SakataShoichi Sakata
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Leptogenesis• Lepton # asymmetry g
enerated by Majorana converted to baryon # asym. by “spharelon”
• => standard model for baryogenesis?
• Need CP violating phases
• Related with leptonic KM phase
(Buchmuller et al.)(Buchmuller et al.)
(Fukugita-Yanagida ‘86)(Fukugita-Yanagida ‘86)
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Good old way
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Good-old way of measuring CPV
P(->e) = P
P(bar->ebar)
= CP[P]P = P - CP[P] = nonz
erogives you CP violation
A useful tool for --> representation: Bi-probability plot H.M. & H. Nunokawa (=MN), JHEP 10 (2001) 001
A useful tool for --> representation: Bi-probability plot H.M. & H. Nunokawa (=MN), JHEP 10 (2001) 001
N. Cabibbo …N. Cabibbo …
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
P = P - CP[P]; sign of m2 or CPV?P = P - CP[P] = P(->e; m2, , a) - P(bar->ebar; m2, , a)
= P(->e; m2, , a) - P(->e; - m2, -, a) If P is insensitive to =>
= P(->e; m2) - P(->e; -m2) = m2-odd P measures sign of m2 in -insensitive region P measures in matter-insensitive region
= P(->e; m2, -, -a)= P(->e; - m2, -, a) (if m2
solar /m2atm << 1)
= P(->e; m2, -, -a)= P(->e; - m2, -, a) (if m2
solar /m2atm << 1)
Low-E superbeam; MN, Sato, Richter, …
Low-E superbeam; MN, Sato, Richter, …
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
TV; Cleanest way of measuring CPV
P(->e)=P
P(e->)=T[P]
PT = P - T[P]
gives you T (=CP under CPT) violation
P = Acos + Bsin + CT[P] = Acos - Bsin + CPT = P - T[P] = 2 Bsin
If = 0 => PT = 0
Experimentally, it is NOT easy => beta beam!
Experimentally, it is NOT easy => beta beam! MN-Parke, hep-ph/0204171MN-Parke, hep-ph/0204171
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
New ways
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
New ways of measuring CPV?• Reactor-LBL combination• BNL strategy with several
oscillation maxima (neutrino only)
• Its low-energy version?
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Reactor measurement of 13
• Independent of , matter effect, 23, 12, solar m2
=> Pure measurement of 13
e disappearance probabilitye disappearance probability
(H.M. Sugiyama, Yasuda, Inoue, Suekane, hep-ph/0211111)
(H.M. Sugiyama, Yasuda, Inoue, Suekane, hep-ph/0211111)
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Reactor-LBL combination
• JPARC-HK neutrino mode, 2 years (4 MW & 540 kton, s/bg accounted)
• 50 ton detectors @Kashiwazaki-Kariwa NPP, 1-10 years
• CP violation can be detected by reactor-LBL combination ! (H.M. H.Sugiyama, hep-ph/0309323 v2 -> PLB)
Principle very simple ! => e appearance at OM + reactor 13 measurement gives you
Principle very simple ! => e appearance at OM + reactor 13 measurement gives you
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Detecting CPV by reactor-LBL combination; details
Realisticdb crucial in sensitivity estimate in phase II
Realisticdb crucial in sensitivity estimate in phase II
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Can Super-K Do the Job?
• JPARC-SK neutrino mode, 10 years (0.75 MW & 22.5 kton, s/bg accounted)
• 50 ton detectors @Kashiwazaki-Kariwa NPP, 1-10 years
• Though less sensitive, Though less sensitive, SK can do a job !SK can do a job !
In the case of “C-evaluation” by the HK review committee
In the case of “C-evaluation” by the HK review committee
the only way to detect CPV without HK?
the only way to detect CPV without HK?
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
We must know sign of m2 in advance, otherwise …
This is nothing but Parameter Degeneracy due to sign (m2)!
MN, JHEP 10 (2001) 001
This is nothing but Parameter Degeneracy due to sign (m2)!
MN, JHEP 10 (2001) 001
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Why so much ambiguity by sign-m2 degeneracy?
The reason is:• Large 2 - 1 (=
/2 ~ in overlapping region of different-sign m2 ==>
• CPC-CPV confusion
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
BNL strategy (hep-ex/0211001)
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
JPARC-HK vs. BNL proposal• L=295 km/E=0.7 GeV vs. L=2540 km/E=0.5-5GeV==> 1st oscillation maximum vs. 1st-3rd oscillation max. • Clean environment for CPV vs. exploring oscillation pattern, sign of m2
13, can prove solar m2, can run with only
<=background ?
<=background ?
1 1
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Low-energy version of BNL strategy?• JPARC accelerator com
plex funded => we will have low-energy neutrino superbeam
• Low-energy beam cannot see 2nd OM because of Fermi motion
• Depend onm2 L/2E => , 3 means the detectors placed at L and 3L =>
• 300 km: Kamioka• 900 km: Seoul, Korea!
Similar to 2-detector strategy in: MN hep-ph/9706281
Similar to 2-detector strategy in: MN hep-ph/9706281
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Shooting Korea
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Bi-probability plot for JPARC-Korea
• Korean detector more important for accurate determination of (steeper slope)
• It is hard to determine sign(m2) from neutrino run only
• Mathematically, there is no degeneracy apart from -> similar to
MN to appear =>
MN to appear =>
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
anti run at the oscillation maximum (reminder)
In the thinnest ellipse limit (KMN)
• There is no degeneracy apart from ->
• sin2is the “distance to the origin”
Kajita-MN, hep-ph/0112345Kajita-MN, hep-ph/0112345
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Conclusion• Real alternative to good-old -anti low-E super
beam does not appear to show up yet• Reactor-LBL may work but confidence level les
s than 2 even with Hyper-K
• BNL strategy interesting to explore but CP sensitivity less than 1 => very long-baseline setting loses statistics
(in conventional beams)• Need to determine sign m2, otherwise CPV-CP
C confusion
<= the only way to detect CPV without HK?
<= the only way to detect CPV without HK?
Low-E version exists but expensive
Low-E version exists but expensive
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
LBL measurement of 13
JPARC-SK 13 sensitivity; OA2°, 5 years
Very simple form!Very simple form!Very simple form !Very simple form !
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Dec. 3-5, 2003 Neutrino Oscillation in Venice Hisakazu Minakata
Reactor-LBL complementarity I
• Pure measurement of 13 by reactors help resolve (2323) degeneracy• If lucky, one may see CP & mass hierarchy
(H.M. Sugiyama, Yasuda, Inoue, Suekane, hep-ph/0211111)
(H.M. Sugiyama, Yasuda, Inoue, Suekane, hep-ph/0211111)