1. Meson Photoproduction with Polarized Targets   production a)  0 at threshold b) Roper and P 11 (1710)   production a) S 11 -D 13 phase rotation in threshold region b) Neutron bump at W = 1680 MeV   ’  production a) separation of S and P wave multipoles close at threshold b)  ’ on the deuteron L. Tiator, Mainz

2. if the amplitudes (multipoles) are real or if the Watson theorem can be applied we only needs to measure a real number for each partial wave if we can neglect all D- and higher partial waves we only have to deal with 4 real quantities: E 0+, E 1+, M 1+, M 1- or E 0, P 1, P 2, P 3 and we are done with d  /d  and  without worrying about target or recoil polarization 2 very famous examples, both from MAMI:  0 p partial waves at threshold  0 p,  + n with full isospin separation in the  region Introduction

3. But for all other cases, where the imaginary parts are unknown we need nucleon polarizations, either polarized targets or recoil polarization measurements

6. Pion photoproduction at threshold P 11 (1440) and P 11 (1710) the photon asymmetry  at from threshold to 200 MeV is very important from all calculations and partial wave analyses up to now, only ChPT is able to describe it (by fitting LECs) most other calculations get even an opposite sign near threshold the P11 resonances are partially hidden states they are very difficult to isolate and are most debated among all resonances

7. the photon asymmetry  at from threshold to 200 MeV is very important for all calculations and partial wave analyses up to now, only ChPT is able to describe it (by fitting LECs) also dispersion relations can not describe the asymmetry

9. the M1- multipole is only poorly known because most observables are very insensitive on this multipole but it is very important because of our interest in the Roper resonance with MAMI B we had already started to measure the G observable, which gives the most direct access to M1- (pending proposal) now in the same channel we can further look into the second P11, which could be a verry narrow state and is currently debated P 11 resonances

12. S 11 (1535) plays an outstanding role in  and e,e‘  and and dominates the total cross section completely at higher energies: S 11 (1650), P 11 (1710), P 13 (1720) play some role around E  =1 GeV or W=1670 MeV a surprising structure appears in  on the neutron (quasi-free) which is still not fully explained speculations about narrow P 11 (1680) (pentaquark) or strong D 15 (1675) (EtaMaid) or P 11 (1710) in coupled-channels approach (Gießen model) small resonance contributions can be observed with polarization observables as interferences with the large S wave, e.g. D 13 (1520) is clearly visible in , even with a branching of only    /  total = 0.0006 Eta photoproduction

13. bg

14. S 11 (1535) plays an outstanding role in  and e,e‘  and and dominates the total cross section completely at higher energies: S 11 (1650), P 11 (1710), P 13 (1720) play some role around E  =1 GeV or W=1670 MeV a surprising structure appears in  on the neutron (quasi-free) which is still not fully explained speculations about narrow P 11 (1680) (pentaquark) or strong D 15 (1675) (EtaMaid) or P 11 (1710) in coupled-channels approach (Gießen model) small resonance contributions can be observed with polarization observables as interferences with the large S wave, e.g. D 13 (1520) is clearly visible in , even with a branching of only    /  total = 0.0006 Eta photoproduction

16. S 11 (1535) plays an outstanding role in  and e,e‘  and and dominates the total cross section completely at higher energies: S 11 (1650), P 11 (1710), P 13 (1720) play some role around E  =1 GeV or W=1670 MeV a surprising structure appears in  on the neutron (quasi-free) which is still not fully explained speculations about narrow P 11 (1680) (pentaquark) or strong D 15 (1675) (EtaMaid) or P 11 (1710) in coupled-channels approach (Gießen model) small resonance contributions can be observed with polarization observables as interferences with the large S wave, e.g. D 13 (1520) is clearly visible in , even with a branching of only    /  total = 0.0006 Eta photoproduction

17. S 11 (1535) plays an outstanding role in  and e,e‘  and and dominates the total cross section completely at higher energies: S 11 (1650), P 11 (1710), P 13 (1720) play some role around E  =1 GeV or W=1670 MeV a surprising structure appears in  on the neutron (quasi-free) which is still not fully explained speculations about narrow P 11 (1680) (pentaquark) or strong D 15 (1675) (EtaMaid) or P 11 (1710) in coupled-channels approach (Gießen model) small resonance contributions can be observed with polarization observables as interferences with the large S wave, e.g. D 13 (1520) is clearly visible in , even with a branching of only    /  total = 0.0006 Eta photoproduction

18. eta photoproduction near threshold

19. main multipoles in the threshold region W threshold = 1487 MeV < W cm < 1600 MeV E thresh =709 MeV < E lab < 900 MeV E 0+ S 11 (1535) dominated E 2-, M 2- D 13 (1520) dominated E 1+, M 1+ background (Born,  ) here we will use the helicity multipoles A,B: A 0+ = E 0+ A 2- = (3 M 2- - E 2- ) / 2 B 2- = E 2- + M 2- B 1+ = E 1+ - M 1+

23. fit to the data

27. no additional information in these „exotic“ observables

30. only T, G and Ox‘ are sensitive to the phase rotation T around 30°-60° and 120°-150° Ox‘ between 30°- 150° G between 45°- 135°

31. Beam-Recoil Double Polarization Experiment in 2007 at MAMI-A1 p ( e, e´p )  in search for the phase rotation in eta electroproduction

34. Recoil Polarization in plane:  =  or  single polarization: double polarization:

35. confirms the phase rotation

36. The question remains: Is the phase rotation of hadronic or electromagnetic origin? This can be answered in quasi-free  production on the deuteron

40. the neutron bump in eta photoproduction at W=1670-1680 MeV

42. schematic view of  on the neutron

43. Photoproduction of  mesons on the deuteron in the presence of a narrow P 11 (1670) resonance resonance parameters for the pentaquark in our calculations: ( A. Fix, L.T., M.V. Polyakov, EPJ A in print ) model with a strong D 15 : model with a narrow P 11 :

44. GRAAL measurements of the beam asymmetry on the proton and on the neutron

45. Photon Beam Asymmetry on the Proton data: Bartalini et al., GRAAL 2007 EtaMaid CQM, Saghai, Li Bonn pw analysis, Sarantsev et al.

46. comparison of GRAAL proton data with pentaquark solutions data: Bartalini et al. GRAAL 2007 EtaMaid ReggeMaid + P11(1670) Bonn pw analysis Sarantsev et al. ReggeMaid - P11(1670) the proton data does not show any pentaquark signature !!

49. can we do something to solve this puzzle? also here the target polarization can very well distiguish between different models, see SFB-MAMI proposal 2007

51. Etaprime photoproduction misplaced or missing resonances dominate already at threshold the current situation with the existing models is very unsatisfactory nowbody knows which resonances play the dominant role the reason for this is: we have only unpolarized diff. c.s. and no polarization observables the same polarization observables, already discussed in eta production are also helpful here: T (and E) other observables will need higher energies

52.  ‘ photoproduction on the proton 3 comparable fits with EtaprimeMaid to JLab/CLAS data of: JLab data 2006 fit I : B+  +  +S 11 (2120) +P 13 (1960)+D 13 (2140) fit II : B+  +  +S 11 (1905)+P 11 (2080) +P 13 (1925)+D 13 (2100) fit III : B+  +  +S 11 (1960)+P 11 (2080) +P 13 (2060)+D 13 (2100)

53. with polarized targets and linearly and circularly polarized photons we can measure up to 8 polarization observables 4 with circular polarization up the maximum beam energy of 1.5 GeV: d , T, E and F 4 with linear polarization are possible up to approximately 1 GeV: , G, H and P Summary The following top priority problems can be attacked: at  0 threshold: Re E 0+, Im E 0+ , T, F Roper P 11 (1440) and second P 11 (1710)G S 11 -D 13 phase rotation in  T, G neutron bumb in  production G, T, E  ‘ partial waves at thresholdT