1 / 61

Baryon Resonances ( N*, D ) , MAID and Complete Experiments

Lothar Tiator Johannes Gutenberg Universität Mainz. Baryon Resonances ( N*, D ) , MAID and Complete Experiments. CRC 1044. Mini-Workshop on Hadronic Resonances, Bled, Slovenia, 2012. references. Singularity structure of the πN scattering amplitude

airell
Download Presentation

Baryon Resonances ( N*, D ) , MAID and Complete Experiments

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lothar Tiator Johannes Gutenberg Universität Mainz Baryon Resonances (N*, D), MAIDand Complete Experiments CRC 1044 Mini-Workshop on Hadronic Resonances, Bled, Slovenia, 2012

  2. references Singularity structure of the πN scattering amplitude in a meson-exchange model up to energies W<2GeV L. Tiator, S. Kamalov, S. Ceci, G.Y. Chen, D. Drechsel, A. Svarc, S.N. Yang Phys. Rev. C 82 (2010) 055203-14 Electromagnetic excitation of nucleon resonances L. Tiator, D. Drechsel, S. Kamalov, M. Vanderhaeghen Eur. Phys. J. ST 198 (2011) 141-170 Unitary isobar model MAID2007 D. Drechsel, S. Kamalov, L. Tiator Eur. Phys. J. A 34 (2007) 69-97 Model dependence of single-energy fits to pion photoproduction data R. Workman, M. Paris, W. Briscoe, L. Tiator, S. Schumann, M. Ostrick, S. Kamalov Eur. Phys. J. A 47 (2011) 143-154 Towards a model-independent partial wave analysis for pseudoscalar meson photoproduction L. Tiator AIP Conf. Proc. 1432 (2012) 162-167

  3. baryon spectroscopy • how to detectN*/D resonances ? • how to measure quantum numbers of N*/D ? • how to measure mass and width of N*/D ? • how to measure branching ratios ? • how to obtain pole postions and residues ?

  4. theoretical poles and experimental bumps poles in the complex plane W bumps on the physical axis W

  5. N* and D states, new in PDG2012 E. Klempt, ATHOS2012, Camogli, Italy: new new new new new new new new

  6. 80s Birthday of Peter Higgs at University of Edinburgh during the week of the Narrow Nucleon Resonances Workshop Edinburgh, June 10, 2009

  7. nucleon response to real and virtual photons

  8. detailed look on nucleon resonances photoabsorption (inclusive cross section)

  9. regime of dynamical models and ChPT regime of quark models and LQCD

  10. theoretical approaches to pion photoproduction ChPT DMT MAID BnGa HDT GICC SAID

  11. SAID

  12. Isobar models and Dynamical models DMT (Dubna-Mainz-Taipei) MAID biggest difference for background terms (e.g. near threshold) : isobar models: only Born plus phenomenological terms dynamical models: include additional pN loop terms similar to cPT

  13. isobar models vs dynamical models (MAID) (DMT)

  14. MAID

  15. e.g. for S11(1535) s-channel resonance contributions unitarity is build in through coupling to other open channels:

  16. unitarity cusp at eta threshold J. Ahrens et al., (GDH and A-2 Collaboration), Phys. Rev. C 74, 045204 (2006) helicity separated cross sections polarized total cross section (helicity asymmetry) unpolarized total cross section

  17. comparison between MAID and SAID

  18. comparison between MAID and SAID Roper P11(1710)

  19. from this comparison between MAID and SAID one may conclude: this must be right!!!

  20. Buta closer look in the partial wave amplitudes (photoproduction multipoles) shows large differences among the different analyses, which use mainly the same data from the world data base CNS-DAC @ GWU strong model dependence in the pw amplitudes due to an incomplete data base: mainly ds/dW and S, some T, P,very few G, H

  21. currently in CNS-DAC data base for g + p -> p0 + p for W< 2 GeV: ds/dW9382G 28Ox‘ 7Tx‘ 0 S1885H 24Oz‘ 7Tz‘ 0 T 353 E 0 Cx‘ 0 Lx‘ 0 P 556 F 0 Cz‘ 0 Lz' 0 mainly only ds/dWand S which count!

  22. comparison of multipoles: MAID – SAID - BonnGatchina from Anisovich et al., Eur. Phys. J. A. 44, 203-220 (2010) imaginary parts of g,p0 multipoles real parts of g,p0 multipoles

  23. comparison of multipoles: MAID – SAID - BonnGatchina from Anisovich et al., Eur. Phys. J. A. 44, 203-220 (2010) real parts of g,p0 multipoles Re Re Re Re no problems for M1+ surprisingly large differences, even though the world data is equally well described

  24. newly measured observables will produce changes at Mainz and Bonn we will soon get good data for: ds/dW, S, T with single (beam/target) polarization and P, E, F, G, Hwith double (beam-target) polarization here example with preliminary target polarization data from Mainz:

  25. changes with newly maesured polarization observables MAID, SAID, BnGa and new fits()with extra T and F data (MAMI, preliminary) E0+ E2- BnGa MAID SAID in our analysis we see large changes in E0+, E2- and M1-

  26. The Complete Experiment with each newly measured polarization observables we can hope to improve the partial wave analyses there is a systematic way to go: the complete experiment

  27. what is a complete experiment? a complete experiment is a set of polarization observables that is sufficient to exactly determine all other possible experiments and all underlying (complex) amplitudes up to 1 phase it does not give us a guarantee to completely determine the baryon resonance spectrum but it certainly will improve it a lot!

  28. in pion alpha elastic scattering:1 complex amplitude (E,q)1 observable is possible in pion nucleon elastic scattering:2 complex amplitudes (E,q)4 observables are possible4 are needed for a complete experiment 0 can be predicted in pion photoproduction:4 complex amplitudes (E,q)16 observables are possible8 are needed (at least) for a complete experiment 8 can be predicted in pion electroproduction:6 complex amplitudes (E,q)36 observables are possible12 are needed (at least) for a complete experiment 24 can be predicted complete experiments in different reactions

  29. complete experimentsfor systemswith 1, 2 and 4 spin degrees of freedom

  30. 1.)

  31. 2.) common choice

  32. 3.) common choice 16 observables analytical solutions with less than 9 obs. are not known

  33. 16 observables expressed in helicity amplitudes

  34. 16 Polarization Observables in Pion Photoproduction

  35. studies on the complete experiment earlier studies on the complete amplitude analysis • Barker, Donnachie, Storrow, Nucl. Phys. B95 (1975) 347-356 • Fasano, Tabakin, Saghai, Phys. Rev. C46 (1992) 2430-2455 • Keaton, Workman, Phys. Rev. C53 (1996) 1434-1435 • Chiang, Tabakin, Phys. Rev. C55 (1997) 2054-2066 recent studies on PWA from complete experiments • Workman, Paris, Briscoe, Tiator, Schumann, Ostrick, Kamalov, Eur. Phys. J. A 47 (2011) 143 • Sandorfi, Hoblit, Kamano, Lee, J. Phys. G 38 (2011) 053001 • Dey, McCracken, Ireland, Meyer, Phys. Rev. C 83 (2011) 055208 • Sarantsev, Anisovich, private comm. (2011), unpublished

  36. requirements for a complete experiment in photoproduction Barker,Donnachie,Storrow (1975): (9 observables needed) „In order to determine the amplitudes uniquely (up to an overall phase of course) one must make five double polarization measurements in all, provided that no four of them come from the same set.“ Keaton, Workman (1996) and Chiang,Tabakin (1997): (8 observables needed) a carefully chosen set of 8 observables is sufficient.

  37. choose any 8 out of 16 observables this set does not work!

  38. choose any 8 out of 16 observables also this set does not work!

  39. choose any 8 out of 16 observables also this set does not work!

  40. choose any 8 out of 16 observables this set works!

  41. choose any 8 out of 16 observables also this set works!

  42. most extensive study by Chiang, Tabakin, Phys. Rev. C55 (1997) 2054-2066

  43. 1 of 6 tables to find a complete set of 8 observables

  44. checking complete experiments with a trick, Mathematicacan at least check exact solutions: Mathematica cannot find the exact analytical solution with 4 amplitudes, but it can find exact solutions for integer-valued amplitudes

  45. pseudo data we have generated about 108 Monte-Carlo events with the MAID, SAID and BnGa models in steps ofand angular bins of • we used: • beam pol.: PT=60% (linear polarization) • Pc=70% (circular polarization) • target pol.:P =80% (long. and trans., frozen spin butanol) • recoil pol.: A =20% (analyzing power, p-scatt on 12C)

  46. a sample of MAID pseudo data based on 108 Monte-Carlo events for g,p0 at 320-340 MeV and comparison with real data MAID pseudo data real data

  47. incomplete amplitude analysis with 8 observables results for an incomplete set of 8 observables with high precision (numbers directly from MAID) dσ/dΩ, Σ, T, P, G, H, E, F W=1217 MeV p(g,p0)p Chaos

  48. complete amplitude analysis with 8 observables results for a complete set of 8 observables with high precision (numbers directly from MAID) dσ/dΩ, Σ, T, P, G, E, Ox, Cx W=1217 MeV p(g,p0)p perfect solution

More Related