Baryon Spectroscopy: Recent Results and Impact – , Erice R. Beck HISKP, University of Bonn Introduction Impact of the new Polarization Data Summary and Outlook Selected Results from JLab, ELSA and MAMI supported by the DFG within the SFB/TR16

only 7 N* and 5  * established in the region 1400 MeV < W < 2000 MeV Nucleon Excitation Spectrum Energy pattern for the dominant states - constituent Quark Models - Dynamic Models, Lattice QCD Various nucleon models predict many more states - weak coupling to  N final state - incomplete data base Introduction ERICE2015 Workshop: focus on hadron structure Elastic and deep inelastic scattering: formfactor (size), parton distribution functions (constituents) Polarizabilities and excitation spectra: information about interaction and dynamics between constituents

Photon L Multipole J P Pion l   Multipole Resonance 1 E1 M1 1/2 3/2 1/2 3/ E 0+ 2 E 2- 1 M 1- 1 M 1+ S 11 D 13 P 11 P 33 2 E2 M2 3/2 5/2 3/2 5/ E 1+ 3 E 3- 2 M 2- 2 M 2+ P 33 F 15 D 13 D 15 spectroscopic notation Isospin Introduction Partial wave analysis : Pion angular momentum Spin

Introduction Status on nucleon-resonances (PDG 2010) : (Isospin I = 1/2) ____ PDG value ____ Quark Model prediction Talk: R. Alkofer Quark models Many more states predicted

Introduction Status on Delta-resonances (PDG2010) : (Isospin I = 3/2) ____ PDG value ____ Quark Model prediction Find missing states Unique PWA necessary Example P 33 - wave Resonances with J P = 3/2

Introduction Lattice calculation :

Problem with a Unique PWA Solution  - threshold until    - region 8 well chosen observables have to be measured to determine the production amplitudes (F 1,F 2,F 3 and F 4 ) above  - threshold additional constraints: (a) s- and p- wave approximation (b) Fermi- Watson theorem same I, J in the final state same scattering phase  IJ two observables sufficient for “complete data base” differential cross section : d  d  beam asymmetry :  Fermi- Watson theorem not valid any more More observable needed to get a unique partial wave solution

Partial waves for the P 33 (1232)

MAMI: O. Hanstein, D. Drechsel, and L. Tiator PL. B 385, 45 (1996) R.B. and H.P. Krahn PRL 78, 606 (1997) Resonance Parameter for the P 33 (1232) LEGS: G. Blanpied. and A. Sandorfi PRL 79, 4337 (1997)

Problem with a Unique PWA Solution  - threshold until    - region 8 well chosen observables have to be measured to determine the production amplitudes (F 1,F 2,F 3 and F 4 ) above  - threshold additional constraints: (a) s- and p- wave approximation (b) Fermi- Watson theorem same I, J in the final state same scattering phase  IJ two observables sufficient for “complete data base” differential cross section : d  d  beam asymmetry :  - Fermi- Watson theorem not valid any more - More observable needed to get a unique partial wave solution - Different final states are important -> coupled PWA

Experimental program for N* Precision data for different final states ( p    n    p , K + , p    ....) Common effort at ELSA, JLab and MAMI Polarization experiments (beam, target and recoil) “complete data base”  p  p +   +    +  p  p +   +    +  p  p +    +  p  p +   +  p  K + +  To constrain PWA  unique PWA solution

courtesy of V. Crede Experimental Program for N*

Crystal Barrel Set-Up BGO-OD Set-Up Talks: V. Metag and V. Vegna Experiments at ELSA Talks: B. Krusche, K. Spieker,S. Gardner, M. Lang and S. Costanza

CBELSA/TAPS Experiment

high polarization at low photon energieshigh polarization at high photon energies Linearly polarized photons: - coherent bremsstrahlung - diamond radiator Circularly polarized photons: - longitudinally polarized electrons - helicity transfer to photon Linearly polarized photons Circularly polarized photons Polarized Photons at ELSA

horizontal cryostat in experimental area data taking Running time over 2500 hours in year 2008 over 2200 hours in year 2009 over 1500 hours in year 2010 High. polarization P + = 83.4 % P - = % fast build-up05h04min (May/June) 05h39min (August) Pol.-time06h10min Polarized Target at ELSA

all three single polarization observables  P, T and cross section  photoproduction of pseudoscalar mesons with polarized beam and target : 4 double polarization observables G, E, F and H can be measured Beam-Target Polarization Observables Beam-Target Polarization Observables JLAB-, ELSA- and MAMI- Experiments: Data on all three single pol. observables  P, T and diff. cross section  and on four double polarization observables G, E and H and F for and

Photon polarization Target polarization Recoil nucleon polarization Target and recoil polarizations X Y Z (beam ) X’ Y’ Z’X’ X’ Z’ Z’ X Z unpolarized linear circular   - - T - H (-P) G F - E - P - O x (-T) O z C x - C z T x L x T z L z (-L z ) (T z ) (L x ) (-T x ) - - Observables in Meson Photoproduction Experiments at ELSA, JLAB, MAMI : polarized photons, polarized targets and 4  detector acceptance Many new results on polarization observables for different final states are coming out Highlights from MAMI : T, , and F, very precise cross section data ! and fine energy binning 4 MeV ! Highlights from ELSA : T, P, , and G, E, H precise polarization data for Highlights from CLAS : T, P, , and G, E, H, F precise polarization data for

__ BnGa Bonn-Gatchina group __ SAID Washington group __ MAID Mainz group Partial wave analysis: Problem with a Unique PWA Solution Total cross section:  tot ~ |A(P 33 )| 2 + |A(D 13 )| 2 + |A(F 15 )| 2 + ….. no interferences between resonances 2. resonance region 3. resonance region

reaction : circularly polarized photons longitudinally polarized proton __ BnGa __ SAID __ MAID Partial wave analysis predictions : Crystal Barrel at ELSA, M. Gottschall, PRL 112 (2014),  1/2  3/2 Helicity Dependent Cross Section for p   2. resonance region 3. resonance region 2. resonance region 3. resonance region 4. resonance region Helicity dependent cross section  1/2 ~ |A(P 33 )| 2 + |A(D 13 )| 2 + |A(F 15 )| 2 + ….. + Interference terms with same L  like E 1+ M 1+ for P 33 or E 2- M 2- for D 13

 1/2 -  3/2 __ BnGa __ SAID __ MAID Partial wave analysis prediction:  1/2 +  3/2 E = CBELSA: Helicity Asymmetry E for p   reaction: Crystal Barrel at ELSA, M. Gottschall, PRL 112 (2014), Angular distributions Sensitive to interference terms with different L  Highest sensitivity to small resonance contributions

reaction: __ BnGa __ SAID __ MAID Partial wave analysis prediction:  1/2 -  3/2  1/2 +  3/2 E = PWA predictions fail already in 2. resonance region CBELSA: Helicity Asymmetry E for p  

CBELSA: Asymmetry G for p   Crystal Barrel at ELSA, A. Thiel, PRL 109 (2012),

E 0+ and E 2- Multipoles E 0+ Multipole, s-wave S 11 (1535), S 11 (1650) and S 31 (1620) E 2- Multipole, d-wave D 13 (1520) and D 33 (1700) ____ BnGa ____ SAID ____ MAID Partial wave analysis: Polarization Observables necessary ! 1.) Constrain energy dependence of multipoles 2.) Reliable extraction of resonance parameter resonance + background contributions

Impact of the new polarization data  Which L max is seen in the new data ?  Truncated partial wave analysis possible L max = 0, S-wave, resonances in S-wave: S 11 (1535), S 11 (1650), S 31 (1620) L max = 1, P-wave, resonances in P-wave: P 11 (1440), P 13 (1710), P 33 (1232), P 31 (?), L max = 2, D-wave, resonances in D-wave: D 13 (1520), D 15 (1680), D 33 (1700), D 35 (?), L max = 3, F-wave, resonances in F-wave: F 15 (1680), F 17 (?), F 35 (?), F 37 (1950) L max = 4, G-wave, resonances in G-wave: G 17 (?), G 19 (?), G 17 (?), G 39 (?)

for L ≤ 1 : only s- and p- waves for L ≤ 2 : only s-, p- and d- waves for L ≤ 3 : only s-, p-, d- and f- waves L max Interpretation of T- Asymmetry

Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient Some indication for L = 4 signal above W = 1850 MeV CBELSA data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of T- Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient Some indication for L = 4 signal above W = 1850 MeV CBELSA data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of T- Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient Some indication for L = 4 signal above W = 1850 MeV CBELSA data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of T- Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient Some indication for L = 4 signal above W = 1850 MeV CBELSA data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

Precision data are necessary - to be sensitive to large L contributions - data sets with full angular coverage - good angular resolution ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1 L max Interpretation of T- Asymmetry CBELSA data

DU12 CM12 MAID BnGa DU12 CM12 MAID BnGa M. Dugger et al. Phys. Rev. C 88, (2013) CLAS:  - Asymmetry  p  n  

DU12 CM12 MAID BnGa M. Dugger et al. Phys. Rev. C 88, (2013) CLAS:  - Asymmetry  p  p  

CBELSA: Preliminary  - Asymmetry  p  p   GRAAL : O. Bartallini et al. EPJ A 26, 399 (2005) CLAS : M. Dugger et al. Phys. Rev. C 88, (2013) CBELSA (preliminary) : F. Afzal et al. DU12 CM12 MAID BnGa

L max Interpretation of  - Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient Some indication L = 4 signal above W = 1750 MeV GRAAL data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of  - Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient L = 4 signal above W = 1750 MeV GRAAL data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of  - Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient L = 4 signal above W = 1750 MeV GRAAL data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of  - Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient L = 4 signal above W = 1750 MeV GRAAL data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1

L max Interpretation of  - Asymmetry Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient L = 4 signal above W = 1700 MeV CLAS data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1 High Precision CLAS Data !

L max Interpretation of  - Asymmetry CLAS data Significant L = 3 signal seen above W = 1500 MeV Below L ≤ 2 seems to be sufficient L = 4 signal above W = 1700 MeV ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1 High Precision CLAS Data !

Precision data are required - for large L contributions - full angular coverage and good angular resolution - small systematic error in angular dependence L max Interpretation of  - Asymmetry CLAS data ___ L max = 2 ___ L max = 3 ___ L max = 4 ___ L max = 1 ___ L max = 5

Impact of the new Polarization Data ____ BnGa_2011 ____ BnGa_2014 ____ MAID _ _ _ SAID_SN11 ____ SAID_CM12 New BnGa energy dependent multipole solution, impact of our new data in the full data base A.Sarantsev et. al Multipoles : Real Part Multipoles : Imaginary Part ____ JüBn_2014

Impact of the new Polarization Data ____ BnGa_2011 ____ BnGa_ with the new polarization data - new fit solution BnGa_2014 Clear convergence seen ! - prediction

____ BnGa_2011 ____ BnGa_2014 ____ MAID _ _ _ SAID_SN11 ____ SAID_CM12 ____ JüBn_2014 Impact of the new Polarization Data ____ BnGa_ with the new polarization data

E 0+ Multipole S 11 (1535), S 11 (1650) and S 31 (1620) E0+ Multipole New BnGa energy dependent multipole solution including the new polarization data G,E,T,P and H Impact of the new Polarization Data ____ BnGa_2011 ____ BnGa_2014 ____ MAID _ _ _ SAID_SN11 ____ SAID_CM12 ____ JüBn_2014

New BnGa energy dependent multipole solution including the new polarization data G,E,T,P and H M1+ Multipole P 33 (1232), P 33 (1620) and P 13 (1720) Impact of the new Polarization Data ____ BnGa_2011 ____ BnGa_2014 ____ MAID _ _ _ SAID_SN11 ____ SAID_CM12 ____ JüBn_2014

M1- Multipole P 11 (1440), P 11 (1710), P 31 (1910) New BnGa energy dependent multipole solution including the new polarization data G,E,T,P and H Impact of the new Polarization Data ____ BnGa_2011 ____ BnGa_2014 ____ MAID _ _ _ SAID_SN11 ____ SAID_CM12 ____ JüBn_2014

E 2+ Multipole D 15 (1675) E2+ Multipole New BnGa energy dependent multipole solution including the new polarization data G,E,T,P and H Impact of the new Polarization Data ____ BnGa_2011 ____ BnGa_2014 ____ MAID _ _ _ SAID_SN11 ____ SAID_CM12 ____ JüBn_2014

Impact of the new Polarization Data New polarization data G,E,T,P and H included in the data base Independent PWA- fits by BnGa, JüBo and SAID Clear convergence between different PWA’s Preliminary work together with: JüBo: D. Rönschen, M. Doering SAID: R. Workmann BnGa: A. Sarantsev

Impact of the new Polarization Data Preliminary work: JüBo: D. Rönschen, M. Doering SAID: R. Workmann BnGa: A. Sarantsev Clear convergence between different PWA’s

StatePDG 2010BnGa PWAPDG 2012 SAID PWA N(1860) 5/2+ N(1875) 3/2- N(1880) 1/2+ N(1895) 1/2- N(1900) 3/2+ N(2060) 5/2- N(2150) 3/2-  (1940) 3/2- ** * *** ** *** ** * ** *** ** *** ** no evidence - confirm known resonances - allow to search for new resonances Impact of the new Polarization Data Multi-channel partial wave analysis, including data from CLAS at Jlab, CB at ELSA, CB at MAMI and other labs Results from meson- photoproduction do now enter the PDG and determine the properties of baryon resonances

Impact of the new Polarization Data Status on nucleon-resonances (PDG 2014) : (Isospin I = 1/2) ____ PDG 2014 ____ PDG 2010 New states have been found

Summary Precise double polarization data are coming out now from ELSA, Jlab and MAMI Impact of the new polarization data, for example In the high W-mass region the final states - the new polarization data constrain the possible multipole solutions - the necessary precision in the data is still missing - full angular coverage and precision is important to find high spin states - polarization observables are essential to get unique PWA- solution - different final state are important - truncated partial wave analysis are possible p  p  ‘ and K +  K +   will be important New polarization data have to be analyzed by the different PWA groups - reduce systematic error and model dependence of resonance parameter extraction - better agreement in the energy dependence of the partial waves

Outlook Polarization data from MAMI - measurements with longitudinal polarized target taken in 2014 and 2015 for E and G data - measurements with transverse polarized target: close to release T and F data for p  0 Polarization data from CBELSA Crystal Barrel upgrade with Avalanche Photodiodes (APD) - measurements with polarized target again beginning of 2016 Polarization data from CLAS - measurements with transverse and longitudinal polarized target: just released E for n  + close to release T and F data for n  + and P, H,G to come for both final states

Thank you for your attention