1. Comparison between ūu and d̄d productions by the γp→ π - Δ ++ and π + Δ 0 reactions at forward π angles at E γ =1.5-3.0 GeV Oct/5/2015 RCNP, Osaka University Hideki Kohri 1

2. Contents SPring-8 LEPS facility New pion data Development of polarized HD target Development of LEPS2 beam line Summary 2

3. SPring-8 LEPS facility 3

4. Electron storage ring 8 GeV electron beam Diameter ≈457 m RF 508 MHz 1‐bunch spread is within σ ＝ 12 psec ． Beam Current = 100 mA 120 km distant from Osaka Super Photon ring ‐ ８ GeV 4

5. SPring-8 beamline map LEPS 5

6. LEPS facility LEPS experiment started in 2000 b) Laser hutch a) SPring-8 SR ring c) Experimental hutch Inverse Compton  -ray Laser light 8 GeV electron Recoil electron Tagging counter Collision Energy spectrum of BCS photons Bremsstrahlung Backward-Compton scattering 36m 70m SSD + Sc hodoscope ScFi + Sc hodoscope Beam intensity < 2.5 x 10 6 for E  =1.5-2.4 GeV (355 nm laser) < 3.0 x 10 5 for E  =1.5-3.0 GeV (266 nm laser) 6

7.  LEPS detector setup 1m1m TOF wall MWDC 2 MWDC 3 MWDC 1 Dipole Magnet (0.7 T) Target Silicon Vertex Detector Aerogel Cerenkov (n=1.03) Start counter LEPS detector was optimized to detect  meson decaying to K + K - at forward angles for removing e + e - BG also removed pions 7

8. LEPS publication Strangeness  p -> K + ,  p -> K +  0 R.G.T. Zegers et al. Phys. Rev. Lett. 91 (2003) 092001  p -> K + ,  p -> K +  0 M. Sumihama et al. Phys. Rev. C 73 (2006) 035214  n -> K +  - H. Kohri et al. Phys. Rev. Lett. 97 (2006) 082003  p -> K +  K. Hicks et al. Phys. Rev. C 76 (2007) 042201(R)  p -> K +  - (1385) K. Hicks et al. Phys. Rev. Lett. 102 (2009) 012501  p -> K +  (1405),   (1385) M. Niiyama et al. Phys. Rev. C 78 (2008) 035202  p -> K +  (1520) N. Muramatsu et al. Phys. Rev. Lett. 103 (2009) 012001  p -> K +  (1520) H. Kohri et al. Phys. Rev. Lett. 104 (2010) 172001  p -> K *0  + S.H. Hwang et al. Phys. Rev. Lett. 108 (2012) 092001  d -> K +  - X A.O. Tokiyasu et al. Phys. Lett. B 728 (2014) 616  meson  meson production on Li, C, Al, Cu T. Ishikawa et al. Phys. Lett. B 608 (2005) 215  p  p T. Mibe et al. Phys. Rev. Lett. 95 (2005) 182001  d ->  d W.C. Chang et al. Phys. Lett. B 658 (2008) 209  n ->  n W.C. Chang et al. Phys. Lett. B 684 (2010) 6  p ->  p,  n ->  n W.C. Chang et al. Phys Rev. C 82 (2010) 015205 Pseudoscaler  p ->  0 p M. Sumihama et al. Phys. Lett B 657 (2007) 32  p ->  p M. Sumihama et al. Phys. Rev. C 80 (2009) 052201(R)  p ->  p,  ’p Y. Morino et al. Prog. Theor. Exp. Phys. (2015) 013D01 Exotic Pentaquark search T. Nakano et al. Phys. Rev. Lett. 91 (2003) 012002 Pentaquark search T. Nakano et al. Phys. Rev. C 79 (2009) 025210 8

9. LEPS publication Strangeness  p -> K + ,  p -> K +  0 R.G.T. Zegers et al. Phys. Rev. Lett. 91 (2003) 092001  p -> K + ,  p -> K +  0 M. Sumihama et al. Phys. Rev. C 73 (2006) 035214   n -> K +  - H. Kohri et al. Phys. Rev. Lett. 97 (2006) 082003  p -> K +  K. Hicks et al. Phys. Rev. C 76 (2007) 042201(R)  p -> K +  - (1385) K. Hicks et al. Phys. Rev. Lett. 102 (2009) 012501  p -> K +  (1405),   (1385) M. Niiyama et al. Phys. Rev. C 78 (2008) 035202  p -> K +  (1520) N. Muramatsu et al. Phys. Rev. Lett. 103 (2009) 012001  p -> K +  (1520) H. Kohri et al. Phys. Rev. Lett. 104 (2010) 172001  p -> K *0  + S.H. Hwang et al. Phys. Rev. Lett. 108 (2012) 092001  d -> K +  - X A.O. Tokiyasu et al. Phys. Lett. B 728 (2014) 616  meson  meson production on Li, C, Al, Cu T. Ishikawa et al. Phys. Lett. B 608 (2005) 215  p  p T. Mibe et al. Phys. Rev. Lett. 95 (2005) 182001  d ->  d W.C. Chang et al. Phys. Lett. B 658 (2008) 209  n ->  n W.C. Chang et al. Phys. Lett. B 684 (2010) 6  p ->  p,  n ->  n W.C. Chang et al. Phys Rev. C 82 (2010) 015205 Pseudoscaler  p ->  0 p M. Sumihama et al. Phys. Lett B 657 (2007) 32  p ->  p M. Sumihama et al. Phys. Rev. C 80 (2009) 052201(R)  p ->  p,  ’p Y. Morino et al. Prog. Theor. Exp. Phys. (2015) 013D01 Exotic Pentaquark search T. Nakano et al. Phys. Rev. Lett. 91 (2003) 012002 Pentaquark search T. Nakano et al. Phys. Rev. C 79 (2009) 025210 9

10. New pion data 10

11.  New LEPS detector setup for taking pion data 1m1m TOF wall MWDC 2 MWDC 3 MWDC 1 Dipole Magnet (0.7 T) Target Silicon Vertex Detector Start counter LEPS detector was optimized to detect  meson decaying to K + K - at forward angles Aerogel Cerenkov counter was removed 11

12. High momentum  data taken in 2007 p( ,  + )X p( ,  - )X E  =1.5-3.0 GeV 0.7<cos   <1 12

13. Fundamental ūu and d̄d production Same acceptance Simultaneous measurements Same proton target ūu production is precisely compared with d̄d production by the γp→ π - Δ ++ and π + Δ 0 reactions 13

14. SAPHIR data published in 2005 C. Wu et al. (SAPHIR collaboration) Eur. Phys. Jour. A 23 (2005) 317     -> p  -      (  +  0 )/  (  -  ++ ) (+0)(+0)  (  -  ++ )   (?) E  (GeV) Clebsch-Gordan coefficients  * favors  +  0 channel 14 N * -> 3  -  ++ : 1  +  0  * -> 3  -  ++ : 4  +  0 Resonance effect t-channel LEPS energy No d  /dcos 

15. Physics motivation of  reactions at E  =1.5-3.0 GeV Low energy  E  =1.5 GeV Missing resonance search s- channel High energy  E  =3.0 GeV Precision of isospin rule is checked. Any other effect ? t- channel     p p p p          N*N* Isospin=1 Isospin=2  (  +  0 )/  (  -  ++ ) = 1/3  (  +  0 )/  (  -  ++ ) = 4/3  (  +  0 )/  (  -  ++ ) = 1/3  (  +  0 )/  (  -  ++ ) = 3  15

16.  (     )/  (     ) ratio expected from Clebsch-Gordan coefficients I=1 (  or  ) exchange in the t-channel should be dominant at forward  angles. Deviation from 1/3 might suggest I=2 exotic meson exchange. Dominant 16

17. High momentum  data taken in 2007 p( ,  + )X p( ,  - )X E  =1.5-3.0 GeV 0.7<cos   <1 17

18. Preliminary differential cross sections for     and     p( ,  - )  ++ p( ,  + )  0 E  (GeV) d  /dcos  (  b) Preliminary 0.7<cos  <0.8 0.8<cos  <0.9 0.9<cos  <0.930.93<cos  <0.97 0.97<cos  < 1 0.7<cos  <0.8 0.8<cos  <0.9 0.9<cos  <0.93 0.93<cos  <0.97 0.97<cos  < 1 18

19. Preliminary ratio  (  +  0 )/  (  -  ++ ) 1/3 is expected from isospin=1 exchange in the t-channel Preliminary 19 Interference between  and  ? (d̄d production / ūu production )

20. Ratio  (  +  0 )/  (  -  ++ ) at 0.966<cos  <1  (  +  0 )/  (  -  ++ ) Average of 29 points is 0.404+-0.005. This is larger than 0.333 by 21+-2%. -0.04 < t < 0 GeV 2 /c 2 20 Preliminary d̄d production is slightly enhanced compared with ūu production (d̄d production / ūu production )

21. Isospin=1  exchange in the t-channel must be the dominant reaction at 0.966<cos  <1 t-channel  (  +  0 )/  (  -  ++ ) = 0.404 +- 0.005 may suggest the precision of Clebsch-Gordan coefficients is about 20% in photoproduction. No other photoproduction reactions can check this more precisely. 21

22. Isospin=2 exotic meson exchange in the t-channel may increase the ratio if it exists t-channel 22

23. Another explanation Proton charge distribution Pion cloud model Small momentum transfer -0.04 < t < 0 GeV 2 /c 2   (ud̄) enhances     procution (d̄d production)  Larger          Bare proton Pion cloud (ud) 23 We do not know how large the sea quark contribution is. Can we know it from these data ? (d̄d / ūu )

24. Impact parameter estimated from uncertainty principle (  x  p ~ h) ~ 24

25. Cross section ratio  (     )/  (      25  (  +  0 )/  (  -  ++ ) t (GeV 2 /c 2 )Estimated impact parameter (fm) 0.7<cos   <1 E  =1.5-3.0 GeV Preliminary ūu production may be suppressed by Pauli principle (d̄d production / ūu production )

26. Photon beam asymmetries 0.9<cos   <1 0.8<cos   <0.9 0.7<cos   =0.8  -  ++  +  0 Azimuthal Angle  (deg.) Nv-Nh Nv+Nh Nv-Nh Nv+Nh 0.7<cos   <0.8 0.8<cos   <0.9 0.9<cos   <1 E  =2.9-3.0 GeV E  =2.8-3.0 GeV E  = 2.8-3.0 GeV E  =2.8-3.0 GeV 26

27. Preliminary photon beam asymmetry for  p ->     and  p ->     reactions  exchange  exchange Preliminary 27

28. Development of polarized HD target 28

29. 16 observables for the  N K  and K  reaction Observable Polarization Beam Target Hyperon Cross section & Single polarization d  /d  - - -  linear - - T - transverse - P - - y Beam-Target double polarization G linear z - H linear x - E circular z - F circular x - Beam and Recoil hyperon double polarization Ox linear - x Oz linear - z Cx circular - x Cz circular - z Target and Recoil hyperon double polarization Tx - x x Tz - x z Lx - z x Lz - z z LEPS measured two observables only. Polarized target and large acceptance spectrometer are needed for complete measurements for advanced N * studies. 29

30. Refrigerators used for polarized HD target SPring-8 RCNP RCNP -> SPring-8 We obtained from ORSAY GRAAL 30

31. N - = N exp(- E - /kT) N + = N exp(- E + /kT) N - /N + = exp((E - - E + )/kT) = exp(  E/kT) = exp(2  p B/kT) k: Boltzmann constant  p : Proton magnetic moment B: Magnetic field T: Temperature Proton polarization P = (N + - N - )/(N + + N - ) = tanh(  p B/kT) E Boltzmann law of statistical mechanics E+E+ E-E- Temperature (mK) Polarization (%) at 17 Tesla H polarization D polarization N 31

32. Dilution refrigerator (DRS) Leiden Cryogenics DRS-2500 ( 3 He/ 4 He dilution refrigerator) Cooling power 2500 μ W at 120 mK Lowest temperature 6 mK Polarization is grown by cooling HD at low temperature at high magnetic field. Superconducting magnet B=17 Tesla 2-3 months later Polarization is frozen. Temperature can be raised to 0.3 K and magnetic field can be decreased to 0.9 Tesla during experiments at SPring-8. DRS 32

33. Polarization degree of proton in HD Aging HD 1 2 3 4 5 6 Year 2008 2011 2012 2013 2014 2015 P H (%) 40% -- 30% 18% 42% 44+-1% NMR Calibration data at T=4.2 K, B=0.9 Tesla Polarization is grown up by ~2000 times NMR After aging HD for 3 months HH We carried out the 6th aging of HD in the beginning of 2015 33

34. NMR coil was not cooled sufficiently ? Temperature sensor Mixing chamber Cold finger Dilution refrigerator Support frame of NMR coil Target cell 34

35. Relaxation time of H polarization in the SPring-8 experimental condition Polarization degree (%) Time (day) Aging HD 1 2 3 4 5 6 Year 2008 2011 2012 2013 2014 2015 T H (days) 100 -- 70 60 --- 239+-66 T=0.3 K B=0.9 Tesla T H =239 +-66 days In 2015 35

36. Development of LEPS2 beam line 36

37. SPring-8 beamline map LEPS2 37 LEPS

38. Recoil electron (tagging) LEP (GeV  -ray) Laser room Inside SR bldg 30m long line 8 GeV electron Laser Outside SR bldg Experimental bldg Beam dump BGOegg LEPS2 spectrometer Storage ring LEPS2 facilityLEPS2 facility 10 times high intensity: Multi-laser injection & Laser beam shaping Best e-beam divergence (12  rad)  Photon beam does not spread out  Construct experimental apparatus outside SR bldg Backward Compton scattering ~135 m Large acceptance experimental bldg BGOegg EM calorimeter Large LEPS2 spectrometer using BNL/E949 magnet  expect better resolutions 38

39. LEPS2 experiment hutch was constructed in 2011 August 20112010 LEPS2 experiment hutch Experiment hall of SPring-8 39

40. BNL-E949 spectrometer was transported to SPring-8 SPring-8 LEPS2 experiment hutch 40

41. LEPS2 solenoid spectrometer system 2.22 m  TPC DC  counter RPC TOP Magnet (BNL-E949) B=1 T Magnet (BNL-E949) B=1 T 41 ☆ Acceptance 5 – 120° (charged particle) 40 – 110° (photon) ☆ Momentum measurement - sideway (30– 120°) TPC Δp/p ~ 0.04 (1 GeV/c) - forward (5 – 40°) DC Δp/p ~ 0.01 (1 GeV/c) ☆ Particle Identification 3σ separation up to 2.7 GeV/c - sideway (50 – 120°) RPC (TOF) - middle (30 – 50°) AC, RPC - forward (5 – 30°) TOP, RPC(<11°)

42. Present experiment at LEPS2 using BGOegg by mainly Tohoku University 42

43. Summary We have been carrying out photoproduction experiments at E  =1.5-2.4 GeV at the LEPS facility since 2000. We newly took high momentum  data at E  =1.5-3.0 GeV in 2007. Precise comparison between ūu and d̄d productions is possible in      and      reactions  Preliminary cross section ratio  (  +  0 )/  (  -  ++ ) is found to be larger than 1/3 expected from the I=1 exchange in the t-channel. Preliminary photon beam asymmetry is typically found to be negative for     and positive for      reaction. We are developing a polarized HD target and a large acceptance LEPS2 spectrometer for near future experiments measuring complete set of physics observables. 43

44. LEPS/LEPS2 collaboration RCNP, Osaka University, Ibaraki, Osaka 567-0047, Japan Research Center for Electron Photon Science, Tohoku University, Sendai, Miyagi 982-0826, Japan Kyoto University, Kyoto 606-8502, Japan Pusan National University, Busan 609-735, Republic of Korea Konan University, Kobe, Hyogo 658-8501, Japan XFEL Project Head Office, RIKEN 1-1, Koto, Sayo, Hyogo 679-5148, Japan Academia Sinica, Taipei 11529, Taiwan Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5143, Japan Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215, Japan Nagoya University, Nagoya, Aichi 464-8602, Japan Ohio University, Athens, OH 45701, USA Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195, Japan Yamagata University, Yamagata 990-8560, Japan Chiba University, Chiba 263-8522, Japan Wakayama Medical College, Wakayama, Wakayama 641-8509, Japan Miyazaki University, Miyazaki 889-2192, Japan National Defense Academy in Japan, Yokosuka, Kanagawa 239-8686, Japan Tokyo Institute of Technology, Tokyo 152-8551, Japan University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada University of Minnesota, Minneapolis, MN 55455, USA Gifu University, Gifu 501-1193, Japan Michigan State University, East Lansing, MI 48824, USA University of Connecticut, Storrs, CT 06269-3046, USA Joint Institute for Nuclear Research, RU-141980 Dubna, Russia National Chung Cheng University, Taiwan 44

45. Thank you 45

46. Photon beam asymmetry  46 t (GeV 2 /c 2 )Estimated impact parameter (fm)  0.7<cos   <1 E  =1.5-3.0 GeV       Preliminary

47.  (  +  0 )/  (  -  ++ ) and  47 Estimated impact parameter (fm)   (  +  0 )/  (  -  ++ ) E  =1.5-3.0 GeV 0.7<cos   <1      Preliminary

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