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Recent Results from LEPS/SPring-8 Experiment

Recent Results from LEPS/SPring-8 Experiment. Wen-Chen Chang Institute of Physics, Academia Sinica, Taiwan On behalf of LEPS Collaboration. Hadron Physics. Studying the strong interactions among the hadronic degree of freedom. fragmentation process in particle physics

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Recent Results from LEPS/SPring-8 Experiment

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  1. Recent Results from LEPS/SPring-8 Experiment Wen-Chen Chang Institute of Physics, Academia Sinica, Taiwan On behalf of LEPS Collaboration

  2. Hadron Physics • Studying the strong interactions among the hadronic degree of freedom. • fragmentation process in particle physics • hadronization process in heavy ion collisions • Degree of freedom: baryon, meson, glueball, tetraquark, pentaquark, meson-baryon & meson-meson resonances, etc. • Controlled interaction: initial and final state. High-energy polarized photon is a useful tool.

  3. Linearly Polarized Photon g (1) Vector ,K* (2) (1) Natural parity (2) Unnatural parity Exchanged particle p N/L* • pN, rN, hN, h’N, wN, fN, KY, KY* • Isospin filter : h, h’, w / L I=0,  N* only p, r / S I=1,  N* and D* Decayed Particles

  4. LEPS Collaborationhttp://www.rcnp.osaka-u.ac.jp/Divisions/np1-b/index.html Research Center for Nuclear Physics, Osaka University：D.S. Ahn, M. Fujiwara, T. Hotta, Y. Kato, K. Kino, H. Kohri, Y. Maeda, T. Mibe, N. Muramatsu, T. Nakano*, T. Sawada, M. Sumihama, M. Yosoi, T. Yorita, R.G.T. Zegers Department of Physics, Pusan National University：J.K. Ahn, S.H. Hwang, S.Y. Ryu Department of Physics, Konan University：H. Akimune Japan Atomic Energy Research Institute / SPring-8：Y. Asano Institute of Physics, Academia Sinica：W.C. Chang, J.Y. Chen, D. S. Oshuev, C.W. Wang Japan Synchrotron Radiation Research Institute (JASRI) / SPring-8： S. Date', H. Ejiri, N. Kumagai, Y. Ohashi, H. Ohkuma, H. Toyokawa Department of Physics and Astronomy, Ohio University：K. Hicks Department of Physics, Kyoto University：K. Imai, M. Niiyama, Y. Nakatsugawa, T. Tsunemi Department of Physics, Chiba University：H. Kawai, T. Ooba, Y. Shiino Wakayama Medical University：S. Makino Department of Physics and Astrophysics, Nagoya University：S. Fukui Department of Physics, Yamagata University：T. Iwata Department of Physics, Osaka University：S. Ajimura, K. Horie, M. Nomachi, A. Sakaguchi, S. Shimizu, Y. Sugaya Department of Physics, Tokyo Institute of Technology：M. Uchida Department of Physics and Engineering Physics, University of Saskatchewan：C. Rangacharyulu Laboratory of Nuclear Science, Tohoku University：T. Ishikawa, H. Shimizu , H. Fujimura, M. Miyabe Department of Applied Physics, Miyazaki University：T. Matsuda, Y. Toi Institute for Protein Research, Osaka University：M. Yoshimura National Defense Academy in Japan：T. Matsumura *: spokesperson Japan, Korea, Taiwan, U.S. and Canada

  5. Super Photon Ring 8 GeV (SPring-8)

  6. 8 GeV electron Backward-Compton scattering Collision Recoil electron Tagging counter 36m 70m a) SPring-8 SR ring Laser light Energy spectrum of BCS photons Bremsstrahlung Compton g-ray b) Laser hutch c) Experimental hutch Schematic view of the LEPS facility

  7. Linearly Polarized Photon Beam Energy Spectrum Linear Polarization 351 nm 257 nm 351 nm 257 nm tagged tagged • E=1.5 ~ 2.4 GeV  3 GeV. • Event by event tagging; E ~10 MeV. • Highly polarized.

  8. Straight section e- (8GeV) Laser Bending magnet g Tagging counter e’ e-γ Collision in Storage Ring

  9. Target, Upstream Spectrometer and Dipole Magnet LH2/LD2 Target (50 mm long) Drift Chamber g SSD Start Counter Cherenkov Detector

  10. Dipole Magnet and Drift Chambers

  11. Time-of-Flight Wall

  12. Particle Identification Charged particle spectrometer with forward acceptance PID from momentum and time-of-flight measurement Reconstructedmass K/p separation p- p+ p K+ Events p+ K+ d K- Momentum [GeV/c] Mass/Charge [GeV/c2] Mass/Charge (GeV) For 1 GeV/c kaon P ~6 MeV/c, TOF ~150 ps, M ~30 MeV/c2

  13. Strangeness Production • Targets of study: • (1020) • , hyperons • Mesons • Features: • Forward angle measurement, including zero deg. • Polarization observables. • Strangeness production

  14. (1020)

  15. (N) is small. • -photoproduction is a unique process to explore Pomeron contribution and other possible new trajectories near threshold! Photo-Production of  Mesons • Pomeron: • Positive power-law scaling of s. • Dominating at large energy. • Natural parity (=+1). • Exchange particles unknown; likely to be J=2+ glueball. • Pseudo-scalar particle: • Negative power-law scaling of s. • Showing up at small energy. • Un-natural parity (= –1). • Exchange particles like ,. • OZI suppressed

  16. Conjectured Exchange Processes • Scalar glueball(Toki, Nakano 1997): daughter Pomeron~s-1.73 , inspired by (0+ glueball, M2~3 GeV2) • Scalar mesons(R. A. Williams 1998): f0(980), a0(980) • Tensor mesons(J. M. Laget 2000): f2(1270) • … • All are involved exotic gluonic components.

  17. Photoproduction of (1020) from Protons and Deuterons pK+K X DK+K X  

  18. LEPS(2005) d/dt|t=tminof pp Pomeron + (,) T. Mibe et al. (LEPS Collaboration), PRL 95, 182001 (2005)

  19. LEPS Decay Angular Distributions Forward angles; -0.2 < t+|t|min <0. GeV2 Curves: fit to the data. 11-1=0.197 ±0.030 11-1=0.189 ±0.024 • W ∝ sin2qhelicity-conserving processesare dominating. • 11-10.2N/(N+UN) ~70%. • Unnatural-parity contribution is non-negligible.

  20. Forward Differential Cross Sections From CLAS E 1.7 1.9 2.1 2.4 CLAS: B. Dey, Baryon ’10 conference (2010).

  21. Coupled-Channel Effect with K(1520) The effect is found to be small. Ozaki et al., Phys. Rev. C 80, 035201 (2009); 81, 059901(E) (2010)

  22. 1/2- N* Resonance Ozaki et al., Phys. Rev. C 80, 035201 (2009); 81, 059901(E) (2010)

  23. 1/2- N* Resonance Ozaki et al., Phys. Rev. C 80, 035201 (2009); 81, 059901(E) (2010)

  24. 1/2- N* Resonance Ozaki et al., Phys. Rev. C 80, 035201 (2009); 81, 059901(E) (2010)

  25. 3/2- N* Resonance A. Kiswandhi et al., Phys. Lett. B 691, 214 (2010)

  26. K+ y K- x Decay Plane f p z g p Production Plane Decay Angular Distribution 

  27. Maximum Likelihood Fit

  28.  ijkof pp in GJ Frame : Pomeron+(π,η), Titov et al., PRC 60, 035205 (1999) • There is no strong energy dependence but slight t dependence. •  000: nonzero, reflecting a violation of t-channel helicity conservation. •  11-1, |Im 21-1 |: ~0.2, a sizable 30% contribution of unnatural-parity exchange processes, other than the natural-parity Pomeron exchange. W.C. Chang et al. (LEPS Collaboration), Phys. Rev. C 82, 015205 (2010)

  29. *(1520,3/2)

  30. Existing Data of (1520) LAMP2 CLAS Forward peaking, t-channel dominates

  31. A.I. Titov, B. Kampfer, S. Date and Y. Ohashi, Phys. Rev. C, 72, 035206 (2005) • The amplitude of Λ* • Low energy : effective Lagrangian formalism • High energy : the Regge model with the K* exchange Main contribution comes from the K*-exchange process

  32. H. Toki, C. Garcia-Recio and J. Nieves, Phys. Rev. D, 77, 034001 (2008) • The chiral unitary model predicts a small coupling between Λ(1520) and NK*. Main contribution comes from the K-exchange process

  33. S.i. Nam, A. Hosaka, and H.-Ch. Kim, Phys. Rev. D, 71, 114012 (2005) Dominance of contact term

  34. S.i. Nam, A. Hosaka, and H.-Ch. Kim,Phys. Rev. D, 71, 114012 (2005) Production from Proton Production from Neutron Large np isospin asymmetry.

  35. Photoproduction of Λ(1520) from p/d N. Muramatsu et al. (LEPS Collaboration), PRL 103, 012001 (2009)

  36. Differential Cross Sections (I) • Consistent with picture of t-channel exchanges. • A smaller cross section compared to LAMP2.

  37. Differential Cross Sections (II) • The production ratio between deuterons and protons target was 1.02±0.11. Production from neutrons is strongly suppressed in the backward K+/0 angles. • A large isospin asymmetry. Consistent with a dominance of contact-term diagram.

  38. Photoproduction of Λ(1520) at Forward K+ Production H. Kohri et al. (LEPS Collaboration), PRL 104, 172001 (2010)

  39. Bump Structure in Energy Dependence • A bump structure is seen at W~2.11 GeV at forward K+ production angle. • Inclusion of a nucleon resonance provides a better description of energy dependence. H. Kohri et al. (LEPS Collaboration), PRL 104, 172001 (2010)

  40. Regge Exchange of K and K* S.i. Nam and C.W. Kao, Phys. Rev. C 81, 055206 (2010)

  41. N* (2080) Resonance J.J. Xie and J. Nieves, Phys. Rev. C 82, 045205 (2010)

  42. K*0(892)

  43. Parallel 1C 8/22 15:00 - 15:20 S. Hwang APFB 2011, Seoul, Korea, August 22~26, 2011 Review on K* photoproduction data Theoretical motivation Preliminary results from LEPS/Spring-8 S Scalar Meson k+ k(800) • Particle Data Group • : The identification of the scalar mesons is“a long-standing puzzle” • Large decay widths which cause • a strong overlap between resonance and background a0+ f0(980) a0- Is a0(980) s(600) k+ k σ(600)  Mass :400~1200MeV, Width: 600 ~ 1000 MeV κ(800)  Mass : 700~900 MeV, Width : ~500 MeV The κmeson is seen in many phenomenological analysis and also in the analysis of D  Kππdecay The existence is still controversial! K*Σ+ photoproduction form threshold to 3GeV Sanghoon Hwang (Pusan)

  44. APFB 2011, Seoul, Korea, August 22~26, 2011 Parallel 1C 8/22 15:00 - 15:20 S. Hwang Review on K* photoproduction data Theoretical motivation Preliminary results from LEPS/Spring-8 gp  K*0S+reaction K : Pseudoscalar meson  unnatural exchange (Pure unnatural exchange  Ps = -1) κ: Scalar meson  natural exchange (Pure natural exchange  Ps = 1) K*Σ+ photoproduction from threshold to 3GeV Sanghoon Hwang (Pusan)

  45. APFB 2011, Seoul, Korea, August 22~26, 2011 Parallel 1C 8/22 15:00 - 15:20 S. Hwang Review on K* photoproduction data Theoretical motivation Preliminary results from LEPS/Spring-8 Parity spin asymmetry for the K* production PRC 74. 015208(2006) “Scalar meson in K* photoproduction“ With  exchange K exchange dominant The parity asymmetry project out the k(800) contribution in the t-channel LEPS facility ideally suite to measure this reaction!! K*Σ+ photoproduction from threshold to 3GeV Sanghoon Hwang (Pusan)

  46. APFB 2011, Seoul, Korea, August 22~26, 2011 Parallel 1C 8/22 15:00 - 15:20 S. Hwang Review on K* photoproduction data Theoretical motivation Preliminary results from LEPS/Spring-8 Missing Mass for (g,K+p-) vs Invariant Mass of K+p- IM(K+p-) K*0(892) MM(g,K+p-) Σ+(1189) K*Σ+ photoproduction from threshold to 3GeV Sanghoon Hwang (Pusan)

  47. APFB 2011, Seoul, Korea, August 22~26, 2011 Parallel 1C 8/22 15:00 - 15:20 S. Hwang Review on K* photoproduction data Theoretical motivation Preliminary results from LEPS/Spring-8 Parity spin asymmetry • GJ frame • helicity frame - with κexchange Preliminary - K exchange domiment PRC 74. 015208(2006) K*Σ+ photoproduction from threshold to 3GeV Sanghoon Hwang (Pusan)

  48. Backward , ’, 0, 

  49. Photoproduction of , ’, 0,  M. Sumihama et al. (LEPS Collaboration), PRC 80, 052201(R) (2009)

  50. d/d (p’p) vs. W Jlab/CLAS data Bonn/ELSA data LEPS data SAID -partial-wave analysis Wide structure is seen above W=2.0 GeV M. Sumihama et al. (LEPS Collaboration), PRC 80, 052201(R) (2009)

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