1. ニュートリノ核子弾性散乱実 験 齊藤 直人（京都大学）

2. NeuSpin Working Group 東工大 東工大 – 柴田さん、宮地さん、武居くん、坂下くん 阪大ＲＣＮＰ 阪大ＲＣＮＰ – 酒見さん 京大 京大 – 齊藤、今井さん 理研 理研 – 後藤さん ＫＥＫ ＫＥＫ – 澤田さん ＮＭＳＵ ＮＭＳＵ –S. Pate その他にも興味を示してくれている方多数 その他にも興味を示してくれている方多数

3. Physics Goal ストレンジネスの偏極  s の直接測定 ストレンジネスの偏極  s の直接測定 – ＤＩＳとバリオン８重項の β 崩壊定数から予測される  s <0 は本当か？ ニュートリノ核子の反応断面積の精密測定 ニュートリノ核子の反応断面積の精密測定 ニュートリノ原子核反応におけるコヒーレント パイオン生成断面積の測定 ニュートリノ原子核反応におけるコヒーレント パイオン生成断面積の測定 –K2K ＣＣの結果を更に improve できるか？ – ＮＣ？

4. From g 1 (x,Q 2 ) to  Proton Deuteron = Proton + Neutron 3 He=Neutron Proton Deuteron = Proton + Neutron 3 He=Neutron Integrate over x (0,1) ！ Integrate over x (0,1) ！ Utilize Octet Baryon  -Decay Constants ！ Utilize Octet Baryon  -Decay Constants ！ –SU(2) OK ！ （ Bjorken SR ） （ Bjorken SR ） Constant in front of D/3

5.  S from SDIS and Global Analysis Global Analyses suffer from a lack of  S data: SU(3) symmetric sea assumed Global Analyses suffer from a lack of  S data: SU(3) symmetric sea assumed In SDIS, with Final State Hadron Detection,  S can be extracted In SDIS, with Final State Hadron Detection,  S can be extracted

6. ストレンジクォークは本当に偏極 してるのか？ Flavor Singlet ⇒ Axial Anomaly Flavor Singlet ⇒ Axial Anomaly –If  g ~ 0.3 axial anomaly contribution alone ~ 0.15/2  ~ - 0.025 –So far  S = - 0.14 ± 0.05 (DIS + Baryon  ) Violation of Eliis-Jaffe Sum Rule ⇒  S ≠ ０ Violation of Eliis-Jaffe Sum Rule ⇒  S ≠ ０ Independent  S measurement would be sufficient to obtain  (together with Baryon  -decay) Independent  S measurement would be sufficient to obtain  (together with Baryon  -decay)

7. Why Should the Nucleon be Strange? The vacuum is strange: The vacuum is strange: chiral symmetry for π, K mesons → Cannot be expected to disappear when one inserts qqq ‘test charge’ into vacuum Cannot be expected to disappear when one inserts qqq ‘test charge’ into vacuum Expected to be generated in perturbative QCD: Expected to be generated in perturbative QCD: s sbar  gluon  quark Also, generated by non-perturbative effects: Also, generated by non-perturbative effects: instantons, chiral soliton models

8. How Strange is the Nucleon? Momentum fraction at Q 2 =20 GeV 2 : Momentum fraction at Q 2 =20 GeV 2 : P s = 4%(CCFR) Electric and magnetic form factors Electric and magnetic form factors at Q 2 =0.48 (GeV) 2 (HAPPEX) G s E + 0.39 G s M = 0.025  0.020  0.014 at Q 2 =0.23 (GeV) 2 (A4) G s E + 0.225 G s M = 0.039  0.034 Contribution to the nucleon magnetic moment -0.1  5.1% (SAMPLE) Contribution to the nucleon magnetic moment -0.1  5.1% (SAMPLE) Not very?

9. Pion-Nucleon σ Term Related to strange scalar density Related to strange scalar density Two recent determinations: Two recent determinations: Maybe y ~ ½ ? Maybe y ~ ½ ? Important later for chiral soliton models of exotic baryons

10. Trial Fit! Utilized NLO  0 calculation (thanks to Vogelsang and Stratmann) Utilized NLO  0 calculation (thanks to Vogelsang and Stratmann) –to find “ relevant-x ” for each p T bin Trial Fit to Trial Fit to –A*x (GRSV ~ 1*x) –A*x*x 22 22 

11. Is this  g Large or Small? Expectation (Phenomenological) Expectation (Phenomenological) –  g ~ 2 to save  thru axial anomaly (if  =0.58 ⇔  s =0 ⇔ EJ SR) –  g ~ 0.3-0.4 to save “ proton spin ” Model predictions Model predictions –  g ~ 2±1 ( … ) –  g ~ -0.4 (Bag model) –No lattice prediction Gauge Invariance Gauge Invariance –See Jaffe ’ s talk –(http://www- ctp.mit.edu/gluonspinbasics080203.pdf) Scale Dependence of  g Scale Dependence of  g –Product  S  g ~ constant –  g (1 GeV)=0.3 ⇒  g ( M Z )=1.5 ⇒  g ( M Z )=1.5 – “ Fine tuning ” by L g

12. Extend x Range A LL (  0 ) from Run 6/7 (65 pb -1 ) will extend x range to larger x A LL (  0 ) from Run 6/7 (65 pb -1 ) will extend x range to larger x STAR jet measurement also provides precision data STAR jet measurement also provides precision data 500 GeV run will cover smaller x - range 500 GeV run will cover smaller x - range

13. Direct photon in Run-2006/7 P1P1 P2P2 k2k2 k1k1

14. RHIC Spin and HERMES SIDIS Complementary! Complementary! –RHIC W No fragmentation ambiguity No fragmentation ambiguity x -range limited x -range limited Useless for transversity studies Useless for transversity studies Otherwise W R ! Otherwise W R ! –HERMES Semi- Inclusive DIS Wide x -range Wide x -range Could be used for transversity studies Could be used for transversity studies

15.  s 測定がもたらす物理的インパク ト 核子のスピンフレーバー構造に対する理解が 深まる 核子のスピンフレーバー構造に対する理解が 深まる –Flavor SU(3) 仮定を超えて 中性子の EDM 中性子の EDM – n -EDM の予言は、 q-EDM and  q に基づく q-EDM and  q に基づく ダークマター探索 ダークマター探索 – ダークマターと核子の相互作用 J.Ellis and R.A.Flores PLB377(96)83 J.Ellis and M. Karliner Lecture at Erice School 95 hep-ph/9601280

16. 荷電カレントコヒーレントパイオ ン生成 K2K results on CC coherent pion production K2K results on CC coherent pion production –Phys. Rev. Lett. 95 252301 (2005)

17. N 弾性散乱 N 弾性散乱 N 弾性散乱断面積 N 弾性散乱断面積 –Where ( Q 2 dropped for brevity) k k’ q P P’

18. BNL E734 (PRD 35 (87) 785) Measurement of p and p elastic scattering Measurement of p and p elastic scattering 170 metric-ton segmented detector @ E ~1.2 GeV 951  p events 776  p events 2.5+0.55 10 19 pot

19. Extraction of Strange FF Fit cross section with dipole approximation Fit cross section with dipole approximation

20. BNL-Experiment 734 Measured elastic scattering cross section Measured elastic scattering cross section and and –Liquid scintillator + Drift Tube 170 t –0.5E19 POT for neutrino and 2.5E19POT for anti- neutrino – Q 2 >0.40 GeV 2 (L.A.Ahrens et.al PRD35(87)785; Reanalysis G.T. Garvey et. al PRC48(93)761) Too High Q 2 Cut-off 79% from Carbon Go to lower Q 2 Extract Pure Proton

21. N-Elastic Scattering Exp at J-PARC N-Elastic Scattering Exp at J-PARC On-axis at near detector hall for T2K Experiment On-axis at near detector hall for T2K Experiment Utilize both two types of LiqScintillator with different H/C mixture for pure proton signal Utilize both two types of LiqScintillator with different H/C mixture for pure proton signal –e.g Bicron BC510A ( H/C =1.212) and BC-533 ( H/C =1.96) –Pure Carbon can be extracted for A Xsection –e.g. 5x5x5m 3 ~ 125 t 1E21 POT possible in one year (130 days) 1E21 POT possible in one year (130 days) –30 times BNL-E734 –Better with polarity change for

22. Sensitivity for  s Assumptions Assumptions –Similar Detection Efficiency to E734: 7.6% for neutrino-N elastic 7.6% for neutrino-N elastic 5.4% for anti-neutrino-N elastic 5.4% for anti-neutrino-N elastic –However with lower Q 2 cut-off : 0.1 GeV 2 Achievable with more uniform detector ? Achievable with more uniform detector ? –25 times more statistics but pure proton only 1/6 Factor 2 reduction in statistical error Factor 2 reduction in statistical error –Systematic control improvements to ~5% E734 7.6% dominated by Beam Flux and Nuclear Effects E734 7.6% dominated by Beam Flux and Nuclear Effects Possible to remove Nuclear Effects which could be larger in lower Q 2 region Possible to remove Nuclear Effects which could be larger in lower Q 2 region

23. Comparison with E734 If  s is the only parameter to be determined If  s is the only parameter to be determined –E734: –J-PARC: But …  s and M A coupled significantly But …  s and M A coupled significantly –E734: –J-PARC: –N.B. other analysis of E734 provided better precision:  = -  s/g A (=1.256) Better determination of  s with Significantly improved Sytematics Separation with M A might be Problematic

24. G0 Physics Asymmetry “ no vector strange ” asymmetry ⇒ A NVS “ no vector strange ” asymmetry ⇒ A NVS –em form factors: Kelly PRC 70 (2004) 068202 inside error bars: stat, outside: stat. & pt-pt syst. inside error bars: stat, outside: stat. & pt-pt syst.

25. G E s and G M s extracted Significant non-zero contributions Significant non-zero contributions

26. Asymmetry measured … Axial Form Factor contribution is suppressed by (1-4s Z 2 )=0.076 Axial Form Factor contribution is suppressed by (1-4s Z 2 )=0.076 -1.65-0.44+0.45

30. 陽子からの散乱と原子核からの散 乱 原子核からが４～５倍 原子核からが４～５倍 Ｑ ２ 分布の違い（モデル） Ｑ ２ 分布の違い（モデル）

34. Hi Intensity Proton Accelerators

35. Completion of J-PARC Power will evolve to ~1 MW in 5 years Power will evolve to ~1 MW in 5 years

36. Summary ストレンジクォークの核子中での役割は 大きいと思われる ストレンジクォークの核子中での役割は 大きいと思われる 偏極 DS の測定は、素粒子・宇宙・原子核 に渡るインパクトがある 偏極 DS の測定は、素粒子・宇宙・原子核 に渡るインパクトがある ニュートリノ散乱で得られる情報は大き い ニュートリノ散乱で得られる情報は大き い 一緒に実験・解析について考えましょ う！ 一緒に実験・解析について考えましょ う！ –http://www.nucl.phys.titech.ac.jp/~neuspin/

37. http://www.nucl.phys.titech.ac.jp/~neuspin/

38. LSND (1993-98) Nearly 49,000 Coulombs of protons on target Baseline 30 m Neutrino Energy 20-55 MeV, 167 tons Liquid scintillator 1280 phototubes

39. MiniBooNE (Started last year)

40. MiniBooNE Signals (10 21 pot) Intrinsic e background: 1,000 events  mis-ID background: 500 events  0 mis-ID background: 500 events LSND-based   e : 1,000 events Approximate number of electron neutrino-like events expected in MiniBooNE with two years of running before cuts

41. Direct Measure of  s (?) Nucleon Neutral Weak Current Nucleon Neutral Weak Current Axial Form Factor: Axial Form Factor: g A, F 1,2 pn known, F 1,2 s measured (PV e) g A, F 1,2 pn known, F 1,2 s measured (PV e) Strange Axial Form Factor: Strange Axial Form Factor:

42. Elastic Scattering p  p Assuming no second-class current … Assuming no second-class current …

43. Conclusion from E734 No decisive determination of Ds due to … No decisive determination of Ds due to … –Q 2 extrapolation down to 0 –Possible contamination from nuclear effects 79% from Carbon 79% from Carbon 1.5 mm resolution  should be improved 1.5 mm resolution  should be improved Pure Hydrogen desirable … at least BG subtraction preferred Pure Hydrogen desirable … at least BG subtraction preferred

44. E734 Target and Detector Calorimeter Calorimeter –Liquid Scintillator (80% of mass) –79% protons are bound in Carbon 21% are free Proportional Drift Tubes Proportional Drift Tubes –1.5 mm position resolution

45. Beam Flux Measured using CC Processes Measured using CC Processes –Anti-nu contamination in nu beam 0.024+\-0.005 –Nu contamination in anti-nu beam 0.087+\- 0.013 Time Structured Beam (every 224 nsec) for BG reduction Time Structured Beam (every 224 nsec) for BG reduction 0.55e19 POT  5.5E5 nu events 2.5E19 POT  2.5E6 anti-nu events

46. Event Topology Cuts& PID Fully contained single track (= proton candidates) Fully contained single track (= proton candidates) Three PDT hits required Three PDT hits required –Q 2 cut > 0.035 GeV 2 Likelihood Functions basing of energy deposit Likelihood Functions basing of energy deposit –P: Probability Density Fn A typical event

47. PID Cuts L (SCIN) and L (PDT) L (SCIN) and L (PDT)