Soo-Bong Kim, Seoul National University, sbkim@phya.snu.ac.kr

Report of the T2KK Workshop

NNN07 at Hamamatsu, Oct. 2-5, 2007

1st & 2nd Workshops on T2KK

http://newton.kias.re.kr/~hepph/J2K http://T2KK.snu.ac.kr

Summary of the 1st & 2nd Workshops T2KK motivation: - T2K-II with HK needs to resolve the degeneracy in the measured CP phase based on the longer L and the larger matter effects

Location of the detector(s): - ~2000 m.w.e. depth for most of physics (H.Sobel, T2KK05) - a candidate site at Kamioka (K.Nakamura, T2KK05) - mountains of 1,200 meters in height are found almost everywhere in the interesting region of Korea (D.Son, T2KK05, C.Ryu, T2KK06)

Resolving the oscillation parameter degeneracy: - mass hierarchy & CP phase (H.Minakata, N.Okamura, E.J.Jeon, T2KK05 S.K.Kang, H.Minakata, K.Senda, T2KK06) - sensitivity as a function of off-axis angle at far detector (N.Okamura, T2KK05/06, F.Dufour, T2KK06, K.Okumura, T2KK06, A.Rubbia, T2KK05/06) - liquid Ar sensitivity (A.Rubbia, T2KK05/06)

Probing non standard physics: - NSI (P.Ko, H.Sugiyama, T2KK06) - test of unitarity (B.Gavela, T2KK06)

3rd Workshop on T2KKUniversity of Tokyo, Tokyo

9/30-10/1, 2007 Site study for HK and one in Korea

(N. Wakabayashi, C. Ryu)

BNL-Fermilab LBL/J-PARC /Systematics at Superbeam exp.

(M. Diwan, T. Ishida, P. Huber)

Oscillation parameter degeneracy

(S.K. Kang, J. Valle)

T2KK sensitivity in resolving degeneracy

(F. Dufour, C. Ishihara, N. Okamura,

K. Okumura, A. Rubbia, K. Senda)

NSP/Test of Unitarity (P. Ko, K. Kimura)

4th workshop at KIAS, Seoul

fall, 2008

http://www-rccn.icrr.u-tokyo.ac.jp/workshop/T2KK07/

Site Study for Hyper-Kamiokande Site studies and cavern analyses by Mitsui Mining & Smelting Co. Ltd. (K. Nakamura, T2KK05)

Study on the joint rock mass by Shimizu Corporation (N. Wakabayashi, T2KK07)

Site Study for the Korean Detector mountains of 1,200 meters in height are found almost everywhere in the interesting region of Korea → Search for a candidate site (D.Son, T2KK05, C.Ryu, T2KK06/07)

Oscillation Parameter Degeneracy Resolving the octant degeneracy

(H. Minakata, T2KK05/06, S.K.Kang T2KK06/07)

13

13

Sign of m232Sign of m232

CP ?CP ?

3

21

e

If 23 ≠/4, is it >/4 or </4 ?

If 23 ≠/4, is it >/4 or </4 ?

3

oror

e

3

How much can T2KK contribute to these measurements?

How to solve the octant degeneracy?H. Minakata, T2KK06

Strategy: Use information which are not proportional to sin2223 x sin2213

Strategy: Use information which are not proportional to sin2223 x sin2213

• Combining reactor measurement of 13

• Requires great precision in reactor 13 measurement

• Powerful at large 13

(N. Okamura T2KK06)

• Detect solar m2 effect (∝ cos223)

• Requires very long baseline (or very large L/E)

• OK even at small 13

(S. Nakayama T2KK06)

Very large L/E + Reactor 13 (C. Ishihara, N. Okamura, A. Rubbia, T2KK07)Very large L/E + Reactor 13 (C. Ishihara, N. Okamura, A. Rubbia, T2KK07)

Sensitivity of Mass HierarchyC. Ishihara, T2KK07

Resolving the degeneracy: T2K-II vs. T2KK

T2K-II (Kamioka only) T2KK (Kamioka + Korea)

Octant of 23 not resolved

Octant of 23 not resolved

Mass hierarchy not determinedMass hierarchy not determined

T2KK has a good sensitivity to resolve the parameter degeneracies.

Sensitivity to the Octant of 23

22

33

sin

2 2 1

3

sin2223=0.96sin2223=0.99

Octant ambiguity of 23 can be resolved at 2 if sin2223 < ~0.97 (almost independent of the value of sin2213 and mass hierarchy).

Octant ambiguity of 23 can be resolved at 2 if sin2223 < ~0.97 (almost independent of the value of sin2213 and mass hierarchy).

T2KK could resolve the 8 hold degeneracy of the oscillation parameters.

OA 2.5 degree for both Kamioka and KoreaOA 2.5 degree for both Kamioka and Korea

S. Nakayama, T2KK06

Sensitivity on Off-axis Angles of the Korea Detector

Suggested that the higher energy beam is better due to the larger matter effect.

However, background might be a serious issue for higher energy beam. Detailed Monte Carlo study (F.Dufour, T2KK06) Liquid Argon detector (A.Rubbia, T2KK05/06)

However, background might be a serious issue for higher energy beam. Detailed Monte Carlo study (F.Dufour, T2KK06) Liquid Argon detector (A.Rubbia, T2KK05/06)

N.Okamura, T2KK05/07

1.0 to 3.0 degree off-axis beam available in Korea.

Sensitivity on Baseline of the Korea DetectorK. Okumura, T2KK06

2.5 degree off-axis beam with L between1,000km and 1,250km is available.

2.5 degree off-axis beam with L between1,000km and 1,250km is available.

The sensitivity does not depend strongly on L !

Potentially many candidate sites !

3 sensitivity to mass hierarchy(True = normal hierarchy)

sin

22 1

3

Kamioka only

L=1000km

L=1050km

L=1200km

L=1250km

L=1100km

L=1150km

Beam Energy Profiles at Sites in KoreaA. Rubbia, T2KK07

1.0 to 3.0 degree off-axis beam available in Korea.

Signal & BG for Various Off-axis BeamsF.Dufour, T2KK06

KamiokaKamioka KoreaKorea

2.5 degree 1.0 degree 1.5 degree

2.0 degree 2.5 degree

signal

BG

sin2(213)=0.1 =1/24 year neutrino run4MW beam

Smaller off-axis angle:Larger matter effect at the 1st osc. Max..

Low E BG more serious.

(2nd osc. Max. difficult to see.)

Smaller off-axis angle:Larger matter effect at the 1st osc. Max..

Low E BG more serious.

(2nd osc. Max. difficult to see.)

signal

BG

T2KK Sensitivities for Various OA Angles F.Dufour, T2KK06/07

Mass hierarchyMass hierarchy CP violationCP violation

Sensitivity of Mass HierarchyA. Rubbia, T2KK07

The longer baseline & higher rate improves mass hierarchy determination

Liquid Ar DetectorA. Rubbia, T2KK05/06/07

n p

Quasi-elastic Deep inelastic

Possibility to study exclusive final states also in Multi-GeV range Detector behaves as a very fine-grained “tracking-calorimeter”

Very small NC and other e background even with the multi-GeV beam. Good for near on-axis beam.

Very small NC and other e background even with the multi-GeV beam. Good for near on-axis beam.

Sensitivity of Liquid Ar DetectorA. Rubbia, T2KK05/06/07

OA 1.0 deg, 28×1021pot, 100 kton mass

Very high sensitivity, especially in the very small sin2213 region.

OA 1.0 deg, 28×1021pot, 100 kton mass

Very high sensitivity, especially in the very small sin2213 region.

sin2213=0.006

CPCPMass HierarchyMass Hierarchy

Probing Non-standard Neutrino PhysicsP. Ko, T2KK06/07

Quantum Decoherence:

Lorentz Symmetry/CPT Violation:

Flavor nonuniversal neutrino interactions with matter:

See their upcoming paper….

Summary

T2KK is an interesting option to resolve the oscillation parameter degeneracy based on the longer baseline and an additional, identical detector in Korea.

For the best experiment, T2KK needs further tuning of some of parameters such as baseline, off-axis angle, detector mass, etc.

T2KK needs a study of more physics opportunities.