Nucleon resonances via H,D(  ) reactions GeV  Experiments at GeV  Hall at LNS : GeV  Hall, 2003: STB tagger II, SCISSORS II, STB special e-beam : Experiments with 0.6 < E  < 1.15 GeV 2006: FOREST construction 1. C,Cu(  ) S 11 (1535) in nuclei; Phys. Lett. B639 (2006) H(  ) proton cross section;  p→  p; Phys. Rev. C (2006) in press 3. D(  ) neutron cross section; S 11, D 15, pentaquark; submitted soon 4. H,D(  0 ) Nucleon resonances 5. C,Si,Cu(  ) E  < 0.8 GeV, threshold region

Heavy baryon (with c/b/t quarks) 3 quarks in short distance one gluon exchange field r < 0.3 fm r ~ 1 fm Light baryon (with u/d/s quarks) 3 dynamical (dressed) quarks effective chiral field (Goldstone boson exchange) diquark-quark clusterization? Perturbed region Non-perturbed region Baryon density Baryon internal energy Why light baryon? Existence of pentaquark state constituent quark model chiral quark soliton model

Spontaneous Chiral symmetry breaking current-quarks (~5 MeV)  Constituent-quarks (~350 MeV) Particles  Quasiparticles

Quark- Model Nucleon Three massive quarks 2-particle-interactions: confinement potential gluon-exchange meson-exchage (non) relativistisc chiral symmetry is not respected Succesfull spectroscopy (?)

Chiral Soliton Nucleon Mean Goldstone-fields (Pion, Kaon) Large N c -Expansion of QCD ????

Quantum numbers Quantum # Coherent :1p-1h,2p-2h,.... Quark-anti-quark pairs „stored“ in chiral mean-field Coupling of spins, isospins etc. of 3 quarks mean field  non-linear system  soliton  rotation of soliton Natural way for light baryon exotics. Also usual „3-quark“ baryons should contain a lot of antiquarks

S 11 D 15 ? P 11, P 13 S 11 D 15 ? P 11, P 13 H,D(g,h) reactions so far reported Nucleon Energy Spectrum  

Electron Beam from 300MeV LINAC 1.2 GeV STB Ring electron Synchrotron Tagged Photon Beam GeV-  Experimental Hall 17 m GeV  experiments at LNS

Pseudosphere 55 cm Backward Block(29) Backward Block(29) Forward Block(74) Forward Block(74) Solid Target Chamber Incident γ    Plastic Counters  Invariant Mass Analysis M  2 = 2E   E   (1 - cos   ) Energy :E =  E i Position :R =  R i E i /  E i SCISSORS II :206 pure CsI Crystals (1.57 str = 12.5% of 4  ) 16.2 X 0 for Forward 148 crystals 13.5 X 0 for Backward 58 crystals  + N →  + X Hydrogen/Deuterium Solid Target t = 8 cm (N T ～ 4×10 23 /cm 2 ) Identification of  meson    = (39.43±0.26)% → Decay Channel →  Decay Channel Experimental setup

M  Gate : 440—620 MeV Empirical Fitting Function: F(M  )= L(M  ) + B(M  ) L(x)=l 0 exp[ l 1 (l 2 - x) + exp( -l 1 (l 2 - x))] B(x)=exp(b 0 +b 1 x + b 2 x 2 )  Invariant Mass Double Differential Yield d 2 N/dp dcos  (at  +N CMS)

 p→  p  p→  N channel open Momentum Cut P  *(3b max)   p→  p 抽出 d  /d  d  /dp 

(p→p)(p→p)  (  p →  N) H( ,  )H reaction For E  < 1.15 GeV  (LNS) ～  (CLAS, ELSA) no third S 11 (Saghai and Li)  (E  ) ～  (  MAID) S 11 (1535) largest S 11 (1650) destructive P 11 (1720) very small + direct (Born, ,  ex.) E  > 1 GeV  p→  N not negligible  (  N) ～  (  p) at 1.1 GeV  MAID

 p→  p process Direct 3 Body          S 11 P 33 New observation:  p→  *→  →  N ～ 50% N(938) N(1535) L=0   (1720) L=0   (1670) L=0   (1750) L=0   (1232)  (1116)  (1192) 3/2 + 1/2 + 1/2 - 3/2 - 1/2 +

 p→  N,  p→  0  p phase space Jido, Oka, Hosaka Prog. Theor. Phys.106,873 (2001) N(938)-S11(1535): parity partner chiral transformation scheme  N N* N   g  N*N* /g  NN =+ or -? S 11 (1535) only is not enough  (  p→  N) = (2 ～ 3)×  (  p→  0  N)  p→  0  N process Doring, Oset, Stottman Phys. Rev. C73, (2006) Chiral unitary approach for meson-baryon scattering D 33 (1700), S 11 (1535), D 13 (1520) Jido et al. Doring et al.

D(  ) reaction ? Original motivation: =2/3, =-1/3 →difference in magnetic transitions between proton and neutron proton target: only S 11 (1535), S 11 (1650) neutron target: D 15 (1675) should be enhanced Present interest: antidecuplet state N* (S=0) originally assigned to P 11 (1710) reanalisys  N scattering PR C69(04) W=1680,  ～ 10 MeV GRAAL preliminary  n coin. Data W=1675 MeV sharp state

The anti-decuplet 1539  < 25 MeV 1862 ～ 1646 ～ 1754 Reevaluation by Diakonov and Petrov, 04 Modified analysis pN scattering Arndt et al. PRC69(04)  n measurement in D(  n)p Kunznetsov et al. preprint (05) J p :1/2 + or 1/2 - ? Width: very small < 10 MeV? Other members: S=0 sector? strongly observed in  n >>  p sharp resonance

CB-ELSA (IX International Workshop On Meson Photoproduction, Crakow,Poland,9.-13,June 2006)  N→  N exclusive measurement Total Cross Section GRAAL (hep-ex )  n→  n exclusive measurement Differential Cross Section cos  ~-0.7 proceedings, preliminary Results  n measurement: quasi-free kinematics (advantage) incomplete arrangement of neutron detectors →low statistics, not high E  resolution, spectrum deformed inclusive  measurement  d→  pn: whole kinematics, complex analysis (disadvantage) high statistics, high E  resolution, spectrum not deformed W, , J p,  transition strength,….. may be obtained precisely.

Comparison with proton data ・ broader momentum distribution ～ 20 MeV increased due to the deuteron target ・ however, good separation between  d→  pn,  d→  pn  momentum distributions in  d→  pn

 angular distributions in c.m. frame of photon incident on nucleon at rest (‘c.m.’)

Total cross section vs E   d→  pn  ’p’→  p  (  d)-  (  ’p’) Narrow resonance! rough estimate peak at E  =1020 MeV apparent width  E  ～ 80 MeV

Effects of nucleon motion in the deuteron FWHM =75 MeV solid line : F(p N ) open circles: CD-Bonn Hulthen Wave Function F(p N ) =p N 2 /((p N 2 +  2 )(p N 2 +  2 )) 2  =45.7 MeV  =260 MeV cos  Angular Distribution E=1 GeV  n cos  1  = 0.5  =10MeV (18MeV in E   =60 MeV(  E  ~100MeV)

Analysis: isobar model +impulse approx. ; neglect p-n interference and f.s.i ; on shell cross section result of  MAID for  p→  p ; result of the isobar model similar to the  MAID calculation Direct term (Born and  and  exchange): from  MAID Resonances: Mass    N A 1/2 A 3/2 D13(1520) S11(1535) varied S11(1650) varied D15(1675) varied F15(1680) D13(1700) P11(1710) varied P13(1720) varied + narrow P 11 or S 11

Angular distributions compared with calculations P 11 at 1670 MeV,  = 7.5 MeV S 11 at 1660 MeV,  = 8.5 MeV,

Total cross section P 11 at 1670 MeV,  = 7.5 MeV S 11 at 1660 MeV,  = 8.5 MeV A 1/2 = 12.5 for P 11 = for S 11 Anti-decuplet N* is established! 1/2 + or 1/2 -

S 11 (1535) S 11 (1650) Narrow P 11 D 15 (1675) P 11 (1710) P 13 (1720) Narrow S 11 neutron cross section Further measurement with FOREST  n coincidence with good geometry Parity + or – need more statistics Branching ratio  0 channel: Miyahara  channel Anti-decuplet in nuclei 7 Li(  ) S 11 (1535) resonance molecular nature? Magnetic moment