1 / 16

T2KK Sensitivity of Resolving q 23 Octant Degeneracy

T2KK Sensitivity of Resolving q 23 Octant Degeneracy. Shoei NAKAYAMA (ICRR, University of Tokyo), T. Kajita, H. Minakata, and H. Nunokawa July 13-14, 2006 2 nd International Workshop on a Far Detector in Korea for the J-PARC Neutrino Beam @ SNU, Seoul, Korea. Motivation.

lulu
Download Presentation

T2KK Sensitivity of Resolving q 23 Octant Degeneracy

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. T2KK Sensitivity ofResolving q23 Octant Degeneracy Shoei NAKAYAMA (ICRR, University of Tokyo), T. Kajita, H. Minakata, and H. Nunokawa July 13-14, 2006 2nd International Workshop on a Far Detector in Korea for the J-PARC Neutrino Beam @ SNU, Seoul, Korea

  2. Motivation • Planned LBL nm (nm) disappearance measurements can determine sin2 2q23 precisely, but cannot distinguish two possible solutions of sin2 q23 if q23 is not maximal. • If the solar term and higher order terms in sinq13 are neglected, nm(nm)  ne(ne) probability depends on q23 through the form ofsin2 2q13 x sin2 q23 . Then, ne (ne) appearance measurements give two degenerate solutions.(sin2 2q13 sin2 q23)1st = (sin2 2q13 sin2 q23)2nd • Accelerator + Reactor could solve this degeneracy in some parameter region (especially at larger sin2 2q13). • Can T2KK solve the q23 octant degeneracy without a help of reactor experiment ?

  3. Strategy • Detect the effect of the solar term using a far detector in Korea, which has a longer baseline. solar term : electron number density : reduced Jarlskog factor

  4. Dm212 = 8.0 x 10-5 (eV2) Dm223 = 2.5 x 10-3 (eV2) sin2 q12 = 0.31 sin22q23 = 0.96 d = 3/4 p normal mass hierarchy Effect of the solar term sin2 q23 = 0.4, sin2 2q13 = 0.01 sin2 q23 = 0.6, sin2 2q13 = 0.0067 Kamioka 0.27Mton ( 4MW, 4yr n + 4yr n ) Korea 0.27Mton ( 4MW, 4yr n + 4yr n ) Number of signal events (BG not included) Solar term is negligibly small due to shorter baseline in Kamioka. Solar term can be seen in low En region in Korea.

  5. Sensitivity study • Assumption • 2.5o off-axis T2K 4MW beam • 4 years n beam + 4 years n beam • Kamioka : 0.27 Mton fid., L = 295 km, r = 2.3 g/cm3Korea : 0.27 Mton fid., L = 1050 km, r = 2.8 g/cm3 • Dm212 = 8.0 x 10-5 (eV2)|Dm223| = 2.5 x 10-3 (eV2)sin2 q12 = 0.31 • Oscillation parameter space (unknown parameters) • sin2 q23 : 0.35 ~ 0.65 [ 31 bins ] • sin2 2q13 : 0.0015 ~ 0.15 [ 98 bins on log scale ] • dCP : 0 ~ 2p [ 100 bins ] • mass hierarchy : normal or inverted [2 bins ]  4 dimensional analysis using no external information on these parameters

  6. Sensitivity study (cont’d) • Binning • e-like : 5 energy bins (0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-1.2 GeV) • m-like : 20 energy bins (0.2-1.2 GeV) • (Kamioka, Korea) x (n beam, n beam)  (5+20) x 4 = 100 bins in total • Systematic errors • e-like bins • BG normalization 5 % • BG spectrum shape 5 % (i-3)/2 (i=1…5 ene bin) • signal normalization 5 % • m-like bins • BG normalization 20 % • spectrum shape 5 % En(GeV)-0.8 / 0.8 • signal normalization 5 % • both bins (7) spectrum distortion in Korea shape diff. btw Kam. and Korea  1s

  7. c2 definition systematic error term detector x beam combination m-like bins e-like bins • f ij : fractional change in the predicted event rate in the ith bin • due to a variation of the parameter ej • j : systematic error parameters, which are varied to minimize c2 for each chioce of the oscillation parameters “ Pull Approach ” G.L.Fogli et al. PRD66 (2002) 053010

  8. An example input answer : sin2 2q13=0.01, d=0.75p sin2 q23=0.4, normal hierarchy Kamioka 0.54 Mt Kamioka 0.27 Mt + Korea 0.27 Mt sin2 2q13 sin2 2q13 dCP sin2 q23 • q23 octant degeneracy • solved !! intrinsic degeneracy sign-Dm2 degeneracy q23 octant degeneracy 90 % C.L. 99 % C.L.

  9. Sensitivity to q23 octant sin2 q23=0.38 sin2 q23=0.44 sin2 q23=0.50 sin2 q23=0.56 sin2 q23=0.62 can determine q23 octant by > 3s 2~3s

  10. Sensitivity to q23 octant (cont’d) sin2 2q13 sin2 q23 sin2 q23 can determine q23 octant for any d by > 3s 2~3s If sin2 q23<0.42 or >0.58 (sin2 2q23= 0.974), q23 octant can be determined by >2s even at very small sin2 2q13 .

  11. d=0 assumed Sensitivity comparison with T2K+Reactor T2K-II + phase II reactor T2KK sin2 2q13 T2KK 2s (rough) > 3s 2~3s sin2 2q13 hep-ph/0601258 T2KK has better sensitivity at sin2 2q13 < 0.06~0.07 . sin2 q23

  12. Sensitivity to mass hierarchy (for various q23) sin2 q23=0.38 sin2 q23=0.44 sin2 q23=0.50 sin2 q23=0.56 sin2 q23=0.62 can determine mass hierarchy by > 3s 2~3s weak dependence on sin2 q23

  13. Sensitivity to leptonic CP violation (for various q23) sin2 q23=0.38 sin2 q23=0.44 sin2 q23=0.50 sin2 q23=0.56 sin2 q23=0.62 can find non-zero sind by > 3s 2~3s weak dependence on sin2 q23

  14. Summary • T2KK (Kamioka 0.27 Mton fid. + Korea 0.27 Mton fid., 4 years n run + 4 years n run) can determine q23 octant by itself if sin2 2q23 <0.97 even for very small sin2 2q13 with realistic estimations of systematic errors.

  15. Supplement

  16. An example input answer : sin2 2q13=0.01, d=0.75p sin2 q23=0.4, normal hierarchy Korea 0.54 Mt Kamioka 0.54 Mt sin2 2q13 sin2 2q13 dCP sin2 q23 dCP sin2 q23 90 % C.L. 99 % C.L.

More Related