1 / 54

N*’s as determined from exclusive reactions

N*’s as determined from exclusive reactions. Volker D. Burkert. Outline: Goals of the N* Program Large Acceptance Detectors N* related data from JLab Status of the N* Analysis Upcoming experiments at Jlab @ 6 GeV Tools for more complex analyses Penta-Quarks and N*’s Conclusions.

jesse
Download Presentation

N*’s as determined from exclusive reactions

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. N*’s as determined from exclusive reactions Volker D. Burkert • Outline: • Goals of the N* Program • Large Acceptance Detectors • N* related data from JLab • Status of the N* Analysis • Upcoming experiments at Jlab @ 6 GeV • Tools for more complex analyses • Penta-Quarks and N*’s • Conclusions PAC25 - Mini Workshop on Nucleon Excited States, January 17, 2004, Kingsmill Resort

  2. Goals of the N* Program • Two main motivations for the N* program: • The study of the nucleon wave function though measurement • of e.m. transition form factors for known resonances, • e.g. D(1232), P11(1440), S11(1520), D13(1520), F15(1680), ... • => analyze Np, Nh,(Npp) final states • The study of the underlying symmetry properties through the search • for SU(6)xO(3) symmetry predicted, yet undiscovered resonances • (“missing resonance problem”), in measurements of Np,Npp, K+L, • K+S, pw, Nr, .. final states.

  3. Large Acceptance Detectors for N* Physics. • CLAS: (photon and electron reactions) • Measure many final states with mostly charged particles simultaneously. • Operate with high luminosity electron beams, and with unpolarized and polarized energy-tagged bremsstrahlung photon beams. • Coverage for photons limited to lab angles < 45o • Crystal Barrel-ELSA: (photon reactions) • CsI with excellent photon detection, e.g. Npopo , Npoh • SAPHIR-ELSA (photon reactions, detector dismantled) • Charged particles in final state • GRAAL (photon reactions): • BGO crystals, with excellent photon detection, limited charged particle, polarized laser-backscattered tagged photon • Crystal Ball – MAMI (photon reactions) • neutral final states in limited W range • BES (Beijing) – N* in e+e- collisions. • LEPS – SPring-8 – (photon reactions) • Charged particle detection in forward dipole spectrometer, and TPC with large angle coverage.

  4. Status of N*- exclusive meson production Experiment Reaction Physics Data Analysis Publication Status Status Status E89-037 ep eppo REM, RSM compl. ongoing PRL88, 122001 (2002) ep enp+ REM, RSM compl. ongoing in preparation E89-038 ep enp+gpN* compl. ongoing in preparation eD epp-gnN* compl. --- --- E89-039 ep ephgNS11 compl. ongoing PRL86, 1702 (2001) E89-042 ep epposLT’ ND compl. ongoing PRC68, 032201 (2003) ep enp+sLT’ ND compl. ongoing in CLAS review E01-102 ep epposLT’ NN* compl. ongoing --- E01-103 ep enp+sLT’ NN* compl. ongoing --- E91-002 ep eppo REM high Q2 compl. ongoing in preparation E99-107 ep eppo REM high Q2 compl. ongoing --- E91-024 ep epw miss. N* compl. ongoing --- E93-006 ep epp+p- miss. Res. compl. ongoing PRL91, 022002 (2003) E99-108 ep epp+p- miss. Res. compl. started --- E93-036 ep eppo Aet, At compl. ongoing PRC68, 035202 (2003) ep ep+n Aet compl. compl. PRL88, 82001 (2002) E93-030 ep eK+L N*, miss N* compl. ongoing PRL90, 131804 (2203) E94-005 ep epp+p- Axial ff compl. ongoing --- E91-023 ep eX Aet compl. ongoing PRL91, 222002 (2003)

  5. Status of N*- exclusive meson production Experiment Reaction Physics Data Analysis Publication Status Status Status E00-112 ep eK+L miss. N* compl. ongoing PRL90, 131804 E91-011 ep epp0 REM,RSM compl. ongoing in preparation E93-050 ep epg(p0) N* compl. compl. nucl-ex/0308009 E94-014 ep epp0 ND(1232) compl. compl. PRL82:45 (1999) ep eph S11(1535) compl. compl. PRD60:052004 (1999)

  6. Experiment Reaction Physics Data Analysis Publication Status Status Status E89-004 gp K+Y miss. N* compl. ongoing nucl-ex/0305028 E91-008 gp ph S11, P11 compl. compl. PRL89, 222002 E93-033 gp pp+p- miss. N* compl. ongoing in prep. E94-008 gD hX N* compl. ongoing - E94-103 gp Np N* compl. ongoing - E94-109 gp pro miss. N* ongoing ongoing - E99-013 g p pw miss. N* ongoing ongoing - E02-112 g p K+Y miss. N* tbd - - E03-105 g p pN N* tbd - - Penta-Quark Baryons and N* Physics E03- gd K+K-p(n) 5-quark B5 sched. ongoing PRL91, 252001(2003) E05-xxx gp K+K-p+(n) 5-quark B5 sched. ongoing PRL92, 01 (2004) K0nK+ Status of N*- exclusive meson production

  7. Status of N*- exclusive meson production --- gd K+K-p(n) 5-quark B5 --- ongoing PRL91, 252001(2003) E03-xxx sched --- --- --- gp K+K-p+(n) 5-quark B5 --- ongoing PRL92, 01 (2004) E04-xxx KonK+, .. Excited Q+ sched. --- --- E04-xxx ed p-p-p-p Search for X-- tbd --- --- E04-xxx ep many Q+, X-- tbd --- ---

  8. missing states 2 2p thresh. 1.5 1 0. 0.5 1.0 1.5 Kinematicsep epX, E=4GeV

  9. ND(1232) Transition • Data published after 1998

  10. ND(1232) – current program (data in hand, partially analyzed) • pp0 with high statistics are currently being analyzed covering Q2 = 0.1 – 6.0 GeV2 • ep ep+n channel for Q2 = 0.1 – 6.0 GeV2 • Data on sLT’ for ppo, np+ in D(1232) region at Q2 < 4 GeV2 • Data on At , Aet for ppo, np+, pp- at Q2 < 4 GeV2 • Single and double polarization resp. functions – at Q2 = 1 GeV2 • Cross section for pp0 at backward p0 angles – at Q2 = 1 GeV2 • pp0 with high statistics taken at Q2 = 6.0 & 7.5 GeV2

  11. Response Functions from p0 Electroproduction in the D(1232) Region ds/dW = sT + esL + esTTcos2f+ 2e(e+1)sLTcosf; si(cosq*,W) CLAS Preliminary

  12. N* program – ND(1232) transition Q2=3GeV2 C L A S p r e l i m i n a r y f

  13. s + es = + q + q A A P (cos ) A P (cos ) T L 0 1 1 2 2 + q + q A P (cos ) A P (cos ) 3 3 4 4 ND(1232) Transition CLAS preliminary

  14. Polarization Observables s =so[1 + P·sp + h(A + P’·sp)] so = no(nLRL + nTRT - nLTRLTcos fpq + nTTRTTcos 2fpq) Aso = no(-n’LTR’LT sin fpq) Pnso = no(nLRnL + nTRnT - nLTRnLTcos fpq + nTTRnTTcos 2fpq) Pl,tso = no(-nLTRl,tLTsin fpq +nTTRl,tTTsin 2fpq) P’nso = no(-n’LTR’nLTsin fpq) P’l,t so = no(-n’LTR’l,tLTcos fpq + n’TTR’l,tTT)

  15. PRELIMINARY Response Functions – Hall A

  16. CLASND(1232) – Asymmetries

  17. ND(1232) Transition • Published + publicly presented data.

  18. HALL A ND(1232) Transition • With current data from CLAS,Hall A & Hall C, JLab data on REM,RSM, and GMD will cover the range Q2 = 0.1 – 7.5 GeV2 with excellent statistics and low systematics. Results projected from completed experiments. Hall A data include recoil and double polarization responses. CLAS data include pp0, np+, beam asymmetries Ae, beam/target asymmetries At, Aet

  19. Analysis Tools for Meson Production above the D(1232) • Unitary Isobar Model (JLab-Yerevan) for single p, h production • Born terms + w, r exchange • Resonances as relativistic Breit-Wigner • Regge exchange at high W • Fixed- t Dispersion Relations (JLab-Yerevan) • Imaginary part of amplitude as sum of Resonances • Real part by dispersion relations • High energy behavior by Regge parametrization • Isobar Model for two-pion analysis (JLab-Moscow-Genova) • Non-resonant 3-body p.s., diffractive Nr, Dp, D13p, • Reggeon exchange at high W, s-channel Breit-Wigner • resonances • Event-based Partial-Wave Analysis with Maximum-Likelihood • fits for Npp final state (RPI-JLab)

  20. Second Nucleon Resonance Region Resonances: P11(1440), S11(1535), D13(1520) • Structure of the Roper P11 ? • |Q3> quark state? • |Q3G> state? • |Ns> molecule? • |Q4Q> penta-quark? • quark core with meson cloud • Structure of the S11(1535) • hard transition form factor? • a 3-quark resonance? • a KS molecule? • Q2 evolution of the D13 helicity structure, A3/2 A1/2 dominance.

  21. Second Nucleon Resonance Region • Single pion and eta production • 1) ep e(np+, ppo), Q2 = 0.1 – 5.0 GeV2 E89-038,42 E1-6 • 2) ed epp-(p) Q2 = 0.1 – 3.5 GeV2 E89-038/42 • 3) ep eph Q2 = 0.1 – 5.0 GeV2 E89-039 • 4) ep eppo Q2 = 0.1 – 3.5 GeV2 E93-036 • 5) ep ep+n Q2 = 0.1 – 3.5 GeV2 E93-036 • Global analysis using DR (JLab-Yerevan) and UIM (JLab-Yerevan) fits performed for 1) - 3) at low Q2 . • First analysis of a consistent set of p0, p+, h cross sections and polarized beam structure functions.

  22. The 2nd Resonance Region Unitary Isobar fit ep enp+ CLAS

  23. UIM DR sT+esL, sTT, sLT Fit to p, h Electroproduction p+ W = 1.23 GeV, W = 1.53 GeV Q2=0.4 GeV2

  24. UIM DR sLT’ (S) Fit to p, h Electroproduction po p+ W = 1.18 – 1.58 GeV W = 1.18 - 1.58 GeV

  25. UIM DR sT, S Global Fit to h Photoproduction h h W > 1.49 GeV W > 1.49 GeV

  26. UIM DR Target asymmetry Global Fit to h Photoproduction

  27. UIM DR stot Global Fit to h Photoproduction

  28. Large longitudinal coupling ! First Results from JLab Global Analysis Zero crossing?

  29. First Results from JLab Global Analysis

  30. DR DR h p UIM UIM A1/2 S11(1535) S1/2 S11(1535) 0 100 10-3GeV-1/2 -20 80 PDG -40 60 0 0.5 Q2 (GeV2) 0 0.5 Q2 (GeV2) First Results from JLab Global Analysis – cont’d

  31. DR h 0 UIM A1/2 -50 -100 0 0.5 Q2 (GeV2) 200 S1/2 DR p A3/2 UIM 0 100 -50 PDG -100 0 0 0.5 Q2 (GeV2) 0 0.5 Q2 (GeV2) First Results from JLab Global Analysis – cont’d D13(1520)

  32. Third Nucleon Resonance Region • Resonances: S31(1620), S11(1650), D13(1700), D15(1675), F15(1680), P11(1710), P13(1720), D33(1700), ….. • Transition form factors in a large Q2 range - test of the Single Quark Transition Model (SQTM) for g + [56,0+] [70,1-], and g + [56,0+] [56,2+] transitions • Does the P11(1710) have a 5-quark component as required by the chiral soliton model of Diakonov et al.? cSM predicted the Q+(1540) as a 5-quark state. • Main tools to study transitions in 3rd resonance region • g*N Np • g*N Npp, many states couple strongly to Npp

  33. Proton Test of the Single Quark Transition Model

  34. Neutron Test of the Single Quark Transition Model

  35. Tools to search for “Missing” Resonances • Search for new baryon states (N*, D) in Npp • Developed Isobar Model for the analysis of pp+p- photo- and electro-production data (Moscow-JLab-Genova). • Developing IM including neutral channel, e.g. np+po, ppopo. • Developed event-based PWA approach for the analysis of pp+p- photo-production data. • Search for new baryon states (N*, D) in KY. • Appropriatetools for resonance analysis are currently lacking. Coupled-channel analysis essential because of large background. • Search for new baryon states (N*) in pw. • Dynamical Model developed by Y. Oh. We are adopting this model to fit experimental data in single channel analysis. Need to include other channels because of background.

  36. p p JP, M D,N* p p r, s p L p Partial Wave Formalism for gp pp+p- • Transition matrix: p+ Tfi = <pp+p-;tf|T|gp;E> =S<pp+p-;tf|a><a|T|gp;E> = Sya(tf)Va(E) p- = p a a • Decay amplitude ya(tf) calculated using isobar model: • e.g. JP, M = ½+, +½ [D++p-]l=1, lPf = +½ + • Production amplitude Va(E) is fitted in unbinned maximum likelihood procedure. Assume Va(E) is independent of E in small energy range. + . . .

  37. Waves in the current analysis JP M Isobars 1/2+ 1/2 Dp (={D++p-, Dop+}) 1/2- 1/2 Dp, (pr)(s=1/2 3/2+ 1/2, 3/2 (Dp)(l=1) ,(pr)(s=1/2) ,(pr)(s=3/2;l=1,3) ,N*(1440)p 3/2- 1/2, 3/2 (Dp) (l=0,2) 5/2+ 1/2, 3/2 (Dp)(l=1), ps 5/2- 1/2, 3/2 (Dp)(l=2) • Total of 35 waves (complex amplitudes) • Diffractive production (“t-channel”) also included

  38. Samples of event-based PWA for gp pp+p- F15(1680)? P33(1600)? A new P33?

  39. Isobar Model for the g*N Npp channel • All established resonances included as Breit-Wigners • Non-resonant Born terms for all D(1232)p isospin channels, and for D13(1520)p channels. • Non-resonant pro production through diffractive ansatz. • High mass behavior through Reggeon exchange. • Good fits to one-dimensional cross sections at low pp+p- masses.

  40. W=1.70 GeV Q2=0. W=1.71 GeV Q2=0.65 GeV2 Isobar Model for the g*N Npp channel

  41. Isobar Model for the g*N Npp channel W=1.71GeV Q2=0.95 GeV2 W=1.71 GeV Q2=1.30 GeV2

  42. Resonances in g*p pp+p- Total cross section CLAS Genova-Moscow Isobar model fit GNpp PDG GNg AO/SQTM (with amplitudes adjusted) missing resonance strength?

  43. Isobar fit to D13(1700) and new PI3 Total cross section CLAS Isobar model fit GNpp PDG GNg AO/SQTM PI3 D13(1700) W(GeV)

  44. Isobar fit - A new PI3 state? CLAS W = 1.74GeV PI3 Mp+p D13(1700) • Data described best by new PI3 Mp+p- 1650-1750 M = 1.72 +/- 0.02 GeV 100-200 GT = 114 +/- 19 MeV Dp : 0. 63+/- 0.12 ~ 0 0.8 - 0.9 Nr : 0.19 +/- 0.09 • consistent with “missing” qp- (deg) P13 state, but mass low known P13

  45. Strangeness Photoproduction Dominant resonances S11(1650) P11(1710) P13(1720) D13(1895) ? Similar data sets exist from SAPHIR. Carnegie Mellon

  46. Strangeness Photoproduction • Sample of data covering the full kinematic range in energy and angles for K+L and K+S, including recoil polarization • Data indicate significant • resonance contributions, • interfering with each other • and with non-resonant • amplitudes. • Extraction of resonance • parameters requires a large • effort in partial wave • analysis and reaction theory.

  47. Strangeness in electroproduction ep eK+Yresponse functions CLAS

  48. Strangeness in electroproduction CLAS g*p K+L backward hemishere forward hemisphere preliminary known N* new N*?

  49. OPE + Pomeron N* Capstick model Sum w g p p g w p0 p p g w N* p p CLAS - Resonances ingp pw? PRELIMINARY Model: Y. Oh

  50. g w p p w N* g p p w - electroproduction above resonance region s CLAS in resonanceregion -1 cosqpw +1

More Related