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Electron/Hadron Physics in Korea (in a personal view)

Electron/Hadron Physics in Korea (in a personal view). 방 형 찬 고에너지협의회 회 서울대 상산 205 Oct. 06, 2005. I. Overview/Electro-Hadron Physics II. Main Physics in Electro-Hadron Physic III. Physics at JPARC IV. Retrospects and Prospects. I. Overview/Electro-Hadron Physics.

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Electron/Hadron Physics in Korea (in a personal view)

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  1. Electron/Hadron Physics in Korea (in a personal view) 방 형 찬 고에너지협의회 회 서울대 상산 205 Oct. 06, 2005 I. Overview/Electro-Hadron Physics II. Main Physics in Electro-Hadron Physic III. Physics at JPARC IV. Retrospects and Prospects

  2. I. Overview/Electro-Hadron Physics I. High Energy ; QCD Physics underlined. 1. Heavy Ion 1. RHIC ; QGP 2. LHC/Alice ; QGP 3. GSI ; QCD phase diagram, Compressed matter 2. Electron /JLAB ; Spin(nucleon) physics, Hadron Structure function, 3. Hadron/Meson ; KEK, JPARC, SPRING8 II. HI/RIB physics ;  Candidate domestic Accelerator as a long term

  3. Spin Physics at Jefferson Lab • Probing quark spins inside the nucleons using polarized electron beam • Measurement of spin structure functions g1(x) and g2(x) • Experimental verification of various QCD sum rules • Comparison of integrals with theoretical calculations • Role of Korean Physicists • - 한국인 책임연구원 JLAB실험 • E01-012 ;Neutron spin structure functions at higher Q2 • E03-109 ;Spin structure functions of the proton • E05-1XX (approved Aug. 2005); L/T separation for quasi-elastic scattering • PR01-016 ; Measurement of the neutron d2 matrix element

  4. Two Examples of Sum Rules • Significant improvement of errors for Bjorken Sum at low Q2 • First measurement of Burkhardt-Cottingham sum rule on the neutron at low Q2 region

  5. Hadron Physics at KEK & Spring8 I. KEK  Strangeness Nuclear Physics - Hypernuclear Physics ; > Effective B-B weak/strong interaction > 3-body B-B weak interaction - KN interaction and K bound nuclear system > Deeply bound dense nuclear state found > Pre-cursor kaon condensation(?) > Dense matter study • Role of Korean Physicists 한국인 연구책임자 주요 KEK-PS 실험 : KEK-PS E307; Hypernuclea Decay E508.; Coincidence meas. Of Hypernuclei

  6. Singles spectrum in NMWD

  7. Comparison of Angular Correlation of He and C • We notice that • We now know that FSI(He) not strong. • Then what are those in Ynnnbb(He). • R(np) enhancement in C over He. •  FSI? • 2. R(nn) enhancement over R(np) both in He and C •  2N? • where R=Nbb/Nnbb 15 counts 8 counts

  8. Y. Akaishi and TY, PRC (2002) Narrowing mechanism: EK < Sp threshold TY and Y. Akaishi, PLB (2002) K- potentials and bound states

  9. Mass spectra nucl-ex/0310018 proton data χ2/DOF = 28.52/31 Gaussian center: 3140.5 MeV/c2 Gaussian sigma: 7.3 MeV/c2 Statistical significance: S/ΔS=120/32= 3.7 σ neutron data

  10. II. Spring8/ LEPS II. HE monochoromatic γ beam  Study of Resonance and Exotic states ; Λ(1405) etc.  Penta-quark state search; • Role of Korean Physicists 한국읹 연구책임자등으로 LEPS 수행중 실험 ; Spring8/LEPS; “Photo-production of Λ(1405)”

  11. Penta-Quark Search at Spring8/LEPS Exotic Baryons nK+ Pentaquark Q+ New Searches J-PARC Outlook

  12. gd Q+ L(1520) @ LEPS Exotic Baryons γ L(1520) New Searches K+/K0 p/n Q+ n/p Q+ J-PARC Quasi-free L(1520) and non-resonant KKp Bump structure f Outlook MMd(γ,K－p) GeV/c2

  13. III. JPARC (2009 실험 개시) - 하드론 물리 연구는 향후 JPARC로 집중 전략

  14. 빔라인 진행 상황 ;  2009년 봄부터 핵물리 실험 수행 예정  기묘도 핵물리 실험용 K1.8 빔라인만 확정  기타 빔라인 논의 중 (K1.1/K0.8, KL,High-p, K1.8-BR)  2005년중 실험제안서 공모하여 빔라인 건설 계획 확정예정

  15. I. High Momentum Beam Physics 1. Direct proton beam • Transversity from Drell-Yann process • Spin physics (with polarized beam) 2. Meson beam • Quark/anti-quark distributions of the meson from Drell-Yann process • Transversity of the nucleon (esp. strange quarks) 3. Exotic Particle Search

  16. Physics with Pencil-typeπ Beam 1. Hypernuclear Physics • 1.1 GeV/c Meson (K+, π+)Beam line • Large solid angle neutron counter array • BB weak Interaction via Decay of Hypernuclei - Three body weak BB interaction 2. K-bound nuclear system study  Pencil π beam for background free (π+, K+) reaction • Kaonic nucleus physics

  17. Summary • 장기적으로 경쟁력있는 가속기 연구소 설립을 목표로 두고. • 중기적으로는 국제적인 가속기 시설 연구에서 visibility를 높이기 위해 노력한다. 이를 위해 좋은 연구 Proposal을 제출하고 성공적으로 수행할 수 있도록 그룹 차원에서도 노력한다. • 이러한 관점에서 한국인으로서 책임 연구를 수행하는 연구를 중심으로 살펴보았고 • 4. 연구에 대한 전망도 이러한 방향에서 살펴보았다. • 5. 앞으로의 연구도 지도적인 역할을 할 수 있는 연구를 중심으로 그룹의 노력을 집중하는 것이 바람직하다는 생각이며 또한 이러한 연구가 순조롭게 진행될 수 있도록 하는 방안을 학계 차원에서 찾을 필요가 있다.

  18. Extra Slides

  19. Proposals at JLab • E01-012 • Neutron spin structure functions at higher Q2 • E03-109 • Spin structure functions of the proton • E05-1XX (approved Aug. 2005) • L/T separation for quasi-elastic scattering • PR01-016 • Measurement of the neutron d2 matrix element

  20. Meson Beams • Strange quarks in the Kaon beams can be used to probe strange quark content in the normal nucleons • transversity of strange quarks • Meson beam on polarized nucleon target producing vector mesons • might be another way to access transversity

  21. Transversity from Drell-Yann •  DIS • - The Bottom Line: DIS cannot measure transversity • - Transversity measurement involves spin flip • - DIS conserves helicity of the constituents From Drell-Yann • Using unpolarized beam and target • Measurement of single-spin asymmetry of the azimuthal distribution of the lepton pair • Access another transversity of the nucleon, h1⊥ • h1⊥ describes transverse quark distributions in unpolarized hadrons

  22. An from pN scattering • JPARC LOI03 will do the similar experiment at JPARC with polarized proton target • With the polarized neutron (3He) target under development in Korea, we can measure An for the pn scattering.

  23. Quark Physics with Meson Beam • Mesons are composed of quark, anti-quark pair • Provides significant amount of anti-quark for Drell-Yann process • From the known knowledge of PDFs of the nucleons, we can learn about q(x) and q(x) inside the meson: quite unique opportunity to study meson PDFs

  24. 1. Spin Physics Overview • Transversity from Drell-Yann Process • unpolarized: probe quark, anti-quark distributions • polarized: study of the transversity • Asymmetry in p+N scattering • Polarized proton target (LOI03) • Polarized neutron (3He) target; under development at SNU • Gluon spin content?

  25. Hypernuclear Physics

  26. II. Hypernuclear Physics at K1.1 GeV/c beamline • Current LOIs; • S=-2 sector Hypernuclear Physics; at K1.8 GeV/c beamline •  Ξ –hypernuclei with (K-,K+). •  Double Λ hypernuclei decay by sequential pion decay. •  γ spectroscopy of double Λ hypernuclei • S=-1 sector Hypernuclear Physics; •  ΔI=1/2 physics ; NMWD of A=4, 5 hypernuclei. • Our Proposal; • 1.“NMweak decay study of Medium heavy Λ hypernuclei • with (π+, K+)” • - To pin down 3-body process in weak decay. • - To fully determine the NMWD branching ratios • of medium heavy Λhypernuclei.

  27. Status of NMWD of Λ hypernuclei 1. Issues to be solved ; - ΔI=1/2 rule - AsymmetryIssue - 3-body process of Weak Decay; Is there such an effcet? How much? Why 3-body effect is so strong that it is comparabe to 2-body effect? - Branching ratios of NMWD; It has been so long since the first realization, but no one was able to determine it yet.

  28. Weak Decay Modes of Λ Hypernuclei Mesonic q~ 100 MeV/c Γπ- ( Λ pπ- ) Γπo ( Λ nπo ) Γm Γnm Γtot(=1/τ) Γp ( Λp  np ) Γn ( Λn  nn ) Nonmesonic q~ 400 MeV/c (1N) (2N) Γ2N (ΛNN NNN)

  29. Non-Mesonic Weak Decay (NMWD) & Issues • 1. B-B Weak Interaction ; • Λ + N -> N + N (ΔS=1 B-B Weak Interaction ) • Long standing puzzle on : Γn/Γp(≡np ratio) • 3. Final State Interaction :It seems one of the important elements to understand NMWD. • 4. 2N NMWD: 3-Body Interaction Process, • Predicted to be a significant component of NMWD, though not experimentally identified yet. • 5. Asymmetry :

  30. Status of Γn/Γp long standig puzzle 1. Γn/Γp Puzzle : Γn/Γpexp>> Γn/Γpth(OPE) ~ 1 ~0.1 2. Recent Development of Γn/Γptheory : 0.3 ~ 0.7 3. Recent Exp. Development: p n p,n simultaneous p,n coinc. ~ 1.0 ~0.5 ~0.5 ~ 0.5 E307 E369 E462/E508

  31. Singles spectrum in NMWD

  32. Setup E462/E508 (KEK-PS K6 beamline & SKS) Solid angle: 26% 9(T)+9(B)+8(S)% π p n K N: 20cm×100cm×5cm T3: 10cm×100cm×2cm T2: 4cm×16cm×0.6cm π K

  33. Energy spectrum in NMWD Q Q Q Q Esum = En + Ep Esum = En1 + En2 • Sharp peak in Ynp(He) at Q value. •  FSI negligible in He. • Broad spec in Ynn(He) • FSI? No. • π- absorption or 2N? • π- can not make it broad. •  Must be 2N effect!! • 3. Ynp(C); FSI is significant. • 4. Ynn(C); Even further degraded. •  Again must be 2N.

  34. Comparison of Angular Correlation of He and C • We notice that • We now know that FSI(He) not strong. • Then what are those in Ynnnbb(He). • R(np) enhancement in C over He. •  FSI? • 2. R(nn) enhancement over R(np) both in He and C •  2N? • where R=Nbb/Nnbb 15 counts 8 counts

  35. Mijung result for 2N

  36. Summary on Hypernuclear Physics • A series of Hypernuclear decay experiments, KEK-PS E307, E369, E462 and E508 have been done at SKS for the study of decay width of NMWD. • 2. We have measured the mass dependence of Λ lifetime, particle spectra, decay asymmetry parameters and coincidence NN correlations of the decay of Λ hypernuclei(He, C) resolving the long standing puzzles on Гn/Гp. • 3. The signatures of (2N)-NMWD processes were found both in the singles and coincidence data and all of them indicates fairly large Γ2N comparabel to Γn. This probably is the first experimental identification of 3-body weak interaction process. • 4. But we still can not say much on each decay width of each channel of NMWD. It is because ot the large Γ2N and its large error bar. • 5. Need a conclusive experiment  at JPARC K1.1 GeV/c. • to determine 1) Γ2N : The strength of 3-body decay process • 2) Γn,Γp ; have to determine their magnitudes.

  37. Proposed Setup for the measurement “NMWD of Medium Heavy Λ Hypernuclei” • Target; Scintillator ; • 2cm x5(?)cm • Need a pencil-like beam profile; • Δx < 1.5cm, Δy<1.5cm, Δz~15cm • 3. Prefered full open 2π angle. • 4. Open target area in Z ; 1 m • 5. Use old setup maximally. We may fill this angles.

  38. Δx = 1.2 cm • Δy = 1.2 cm • L(flat) ~ 20 cm • D(Q10) ~ 1 m • This profile probaly would be fine for the decay meas.

  39. Yield Estimation • Yield Estimation for same tgt and Nπ+ of E508, • 1. Nnpnbb=8, Nnnnbb=15, NNNN= 7(3) • 2. εp ~ 5 εp0  8 εp0 • 3. εn ~ (5/3) εn0  (7/3) εn0 • Nnpnew = 5 (5/3) Nnp= 8.3 Nnp =65  145 • Nnnnew = (5/3)2 Nnn= 2.8 Nnn =42 counts  84 • NNNNnew = 5 (5/3)2 NNNN = 14 x 7(3) ~ 100 (40) triple coin.  300(120)  Γ2N with 15% error, not with 70-100% error!!

  40. K Atomic states Nuclear state K- Deeply Bound K-Nuclei Current LOI on Dense K-nuclear states;  (K-,N) reaction  (K-,π-) and (π+,K+) reaction One LOI, but very inclusive one.

  41. Status of the study of Deeply bound K-nucleus Stark effect KpX (KEK) M. Iwasaki et al, 1997 DEAR G1s • = - 323 ± 63 ± 11 eV G = 407 ± 208 ± 100 eV E1s e1s } -500 0 500 Kaonic hydrogen puzzle repulsive attractive f s p d 1000 800 E2p Izycki et al, 1980 600 widthG1s[eV] 400 200 Bird et al, 1983 Davies et al, 1979 0 shifte1s[eV] aT=0 =-1.7 fm aT=1 = 0.37 fm Repulsive Shift

  42. KN interaction • Before 1997: Confusing situation • 1997 KpX experiment at KEK; Iwasaki et al. PRL(1997): K-p atom shift: “repulsive”, • Indicating the K-p interaction isstrongly attractive • Consistent with the view thatL(1405)is 1s bound state of K-p • Atomic ground state is 2s bound state. • --->> Akaishi-Yamazakiconstructed a phenomenological KN interactioncombining 1. Kp scattering length 2. K atom data 3. Λ(1405) as Kp bound state

  43. Y. Akaishi and TY, PRC (2002) Narrowing mechanism: EK < Sp threshold TY and Y. Akaishi, PLB (2002) K- potentials and bound states

  44. Kaonic Bound States • Believed to be non-existing: G > BE • However, Akaishi-Yamazaki (2002) predicted: - K--p interaction so strong - strongly bound states - shrinks nuclei --> deeper bound states - deep enough: the main decay channel KN-->SN closed • BE > 100 MeV: narrow bound states • High nucleon density: ρ ~ (4-7)ρ0 - chiral symmetry restoration? - deconfined quark-gluon phase?

  45. Diagram Kaon Bound System

  46. ppK- bound system - kaonic “hydrogen molecule”

  47. 2. Experiment

  48. Proton PID on NC

  49. 4He(K-stopped,p) spectra Semi-inclusive momentum spectrum A significant peak structure Exists just below 500 MeV/c, on a continuum due to 1. Formation via 2. Hypernuclear formation and its non-mesonic two-body decay Discovery of a strange tribaryon S0

  50. Mass spectra nucl-ex/0310018 proton data χ2/DOF = 28.52/31 Gaussian center: 3140.5 MeV/c2 Gaussian sigma: 7.3 MeV/c2 Statistical significance: S/ΔS=120/32= 3.7 σ neutron data

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