Report

Analysis of 2p Production presented by V.I.Mokeev gp→2pN exclusive channels in N* studies. •modeling of 2p photo- and electroproduction by tree level meson-baryon diagrams. •phenomenological analysis within the framework of JLAB-MSU model. •N* studies in combined analysis of major exclusive channels. Argonne-Osaka coupled channel approach. •Conclusions. V.I.Mokeev N* Analysis Workshop’ 1 The p-p+p electroproduction amplitudes are needed for credible evaluation of N* parameters in coupled channel analysis. Exclusive channels in pN scattering responsible for ISI&FSI in meson electroproduction CLAS data on meson electroproduction at Q2<4.0 GeV2 p(e,e’)X (trigger) p(e,e’p)p0 p(e,e’p+)n p(e,e’pp+)pp(e,e’pp+)X V.I.Mokeev N* Analysis Workshop’ 2 Why the studies of 2p electroproduction are important. D33(1700) electrocouplings from world data on 1p electroproduction from CLAS data on 2p electroproduction combined analysis of 1p/2p CLAS data V.I.Mokeev N* Analysis Workshop’ 3 Meson-baryon (MB) models (partial list of references). 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. L. Luke, P. Soding, Springer Tracts in Modern Physics 59 (1971) 39. L.Y. Murphy, J.-M. Laget, DAPNIA-SPHN-96-10. J.A. Gomez Tejedor, E. Oset, Nucl. Phys. A571 (1994) 667. J.A. Gomez Tejedor, E. Oset, Nucl. Phys. A600 (1996) 413. J.C. Nacher, et. al., Nucl. Phys. A695 (2001) 295. S. Ong, J. Van de Wiele, Phys. Rev. C63 (2001) 024614. W. Roberts, A.Rakotovao, hep-ph/9708236 W. Roberts, T.Oed, Phys. Rev. C71 (2005) 055201. M. Hirata, K. Ochi, T. Takaki, Phys. Rev. C56 (1997) 1472. M. Hirata, N. Katagiri, T. Takaki, Phys. Rev. C67 (2003) 034601. M. Ripani, V.I. Mokeev, et. al., Nucl. Phys. A672 (2000) 220. V.I. Mokeev, et. al., Phys. of Atom. Nucl. 64 (2001) 1292. V. Bernard, N .Kaiser, U.G. Meissner, Eur. Phys. J. A11 (2001) 209. A. Fix, H. Arenhovel, Eur. Phys. J. A25 (2005) 115. V.I.Mokeev N* Analysis Workshop’ 4 Valencia group approach. (applicable at W<1.6 GeV) M=p,r; B=p,D,P11(1440),D13(1520), D33(1700); relevant for W<1.6 GeV Isobar channels: pD, rp, pP11(1440) & pN background non fully relativistic description (resolved in ref. 6 at p.5); c-numbers instead of vertex functions (in part resolved in ref. 6 at p.5) ; no ISI&FSI effects The contributions: -pD Born terms - to pD extra terms of JM06 - to direct 2p production of JM06 -s-channel N* excitation V.I.Mokeev N* Analysis Workshop’ 5 Fully relativistic description. W.Roberts approach. p,V-mesons and all N*,D* of 1/2, 3/2 spin are included. A general framework for most comprehensive MB description in N* excitation region. N r g N*,D* p Open problems: •reliability of effective MB lagrangians→test against data on N* LS partial decay widths; •vertex functions, most of them are still unknown; •ISI&FSI should be implemented V.I.Mokeev N* Analysis Workshop’ 6 A.Fix and H.Arenhövel approach. M=p,r,s, B=N,D All N*,D* with masses less then 1.8 GeV are included to s-channel amplitudes. Effective description of ISI&FSI within the framework of diffractive absorptive ansatz Open problems: •completeness of mechanisms at high W; •credibility of approximations for ISI&FSI, considering huge absorptive effects V.I.Mokeev N* Analysis Workshop’ 7 How well MB approaches working? Reasonable description of fully integrated cross-sections in all approaches, BUT huge ad hoc absorptive corrections at W>1.6 GeV. 0p0p ABBHHM, TAPS data in gp→p comparison with A.Fix, H.Arenhovel model V.I.Mokeev N* Analysis Workshop’ 8 Cont’d gp→p+p0n TAPS data gp→p0p0p E.Oset, et.al. model E.Oset,et.al. model Discrepancies Due to problems with description of 1-diff cross-sections neither of MB approaches was ever used to extract N* parameters from the 2p photo and electroproduction data. V.I.Mokeev N* Analysis Workshop’ 9 New prospects for N* studies in 2p production. Effective lagrangians + phenomenological parametrization hybrid approach. ELSA, MAMI, GRAAL photo- and CLAS electroproduction data extended amount of measured observables considerably. CLAS electroproduction data. For unpolarized beam/target, the final state, gr,v→p-p+p reaction offers 9 independent 1-differential cross-sections in each (W&Q2) bin. All these cross-sections are available from CLAS for the first time. Contributing mechanisms may be established in phenomenological analysis of all available data combined. It is joint JLAB/MSU effort. V.I.Mokeev N* Analysis Workshop’ 10 JLAB-MSU model (JM05) for 2-p electroproduction. V.I. Mokeev, V.D.Burkert et.al., Proc. of the Workshop NSTAR2005, World scientific, p.47 3-body processes Quasi-2-body mechanisms included •All well established N* with pD decays +P33(1600)&P11(1710)&P13(1720)&P33(1920) 3-star states and 3/2+(1720) candidate. •Reggetiezed Born terms & effective FSI&ISI treatment (Ref. 11 p.5). •extra pD contact term •All well established N* with rp decays +P11(1710)&P13(1720) 3-star states and 3/2+(1720) candidate. •Diffractive ansatz for non-resonant part & r-line shrinkage in N* region. V.I.Mokeev N* Analysis Workshop’ 11 con’d Quasi-2-body mechanisms included 3-body processes (p-) •for p+D013(1520) set of Born terms similar to what was used for pD isobar channels. (P++33(1640)) (p+) F015(1685) •for p+F015(1685), p-P++33(1640) 3-body contact term with exponential propagators of isobars in 2 body intermediate states. Direct 2p production. Exchange processes, parameterized as: M d g A (W , Q ) U p / g U 2 V.I.Mokeev N* Analysis Workshop’ 1 p W 2 4 e 2 b ( P - P min ) ( P1 P2 ) 12 Evidences for processes beyond isobar channel superposition in 2p production. CLAS data M.Ripani, V.D.Burkert, et. al. Q2=0.95 GeV2 2p direct mechanisms The contributions from all isobar channels combined still underestimate 2p cross-sections. 2p direct mechanisms are needed to reproduce CLAS/world data. V.I.Mokeev N* Analysis Workshop’ 13 Evidences for exchange mechanisms in direct 2p production from the CLAS data. E93-006 CLAS data fit with remaining mechanisms: W=1.49 GeV Q2=0.65 GeV2 exchange processes Q2=0.95 GeV2 3-body phase space remaining mechanisms shown on slide 6 V.I.Mokeev N* Analysis Workshop’ 14 p+p-p cross-sections off protons from the fit of mass and p- angular distributions within the framework of JM05. s, mcbn CLAS data M.Ripani, V.D.Burkert, et. al. Q2=0.65 Gev2 Q2=0.95 Gev2 Q2=1.30 Gev2 Reasonable description of invariant mass and p- angular distributions were achieved without any need for an additional mechanisms beyond implemented to JM05. V.I.Mokeev N* Analysis Workshop’ W, GeV 15 Global fit of complete set of unpolarized 1-differential cross-sections within the framework of JM06 model (1.3<W<1.6 GeV & 0.25<Q2<0.60 GeV2) . JM06 full p-D++ p +D 0 2p direct ai-angular distributions were calculated with parameters of JM06 fitted to 6 other 1-diff. cross-sections. Successful description of all E94-005 data was achieved. Complete data on unpolarized 1-differential cross-sections for the first time available from CLAS allowed us to establish all significant mechanisms contributing to the 2p electroproduction. V.I.Mokeev N* Analysis Workshop’ 16 Modification of parameterization for direct 2p amplitudes JM05 JM06 JM06 + A (W ) U p g U p e bt pp - ( Pp + Pp ) t p p - ( Pp - - Pp ) 2 A (W ) U p g U p e bt pp - bt ( Pp + Pp ) e t gp + ( Pp + - Pg ) 2 V.I.Mokeev N* Analysis Workshop’ gp + t gp + A (W ) U p g U p e bt pp - ( Pp + Pp ) e t g p ( P p - Pg ) bt g p t gp 2 17 P11(1440) and D13(1520) electrocouplings. P11(1440) D13(1520) from analysis of E94-005 CLAS 2p data within the framework of JM06 from analysis of 1p CLAS data from analysis of E93-006 CLAS 2p data within the framework of JM05 combined analysis of 1p/2p CLAS data V.I.Mokeev N* Analysis Workshop’ 18 Combined analysis of major exclusive electroproduction channels within the framework of the coupled channel (cc) approach, using phenomenological input from JM06 Argonne-Osaka approach (TS.H.Lee, et.al.) is only available worldwide, capable to account for full complexity of FSI in the ppN final states. resulting AO amplitudes “bare” amplitudes, established within the framework of JM06 “bare’ amplitudes from other electroproduction channels ppN unitarity cut V.I.Mokeev N* Analysis Workshop’ 19 Current efforts in combined 1p/2p analysis. Hall B group & EBAC collaboration. • The amplitudes of all significant mechanisms in the 1p/2p exclusive channels were determined in phenomenological analysis of the CLAS data (I. Aznauryan for 1p, JM06 for 2p). Modification of these amplitudes by FSI, is under evaluation, using AO approach at 0.25< Q2<1.5 GeV2 and W<1.5 GeV, where only 1p/2p channels contribute • 1p/2p CLAS electroproduction data will be re-fitted, using non-resonant amplitudes accounting for FSI. Clobal fit of observables from major exclusive channels, accounting for unitarity, will be gradually extended up to 2.0 GeV W, allowing us to extract most reliable data on electrocouplings for an entire excited nucleon spectrum. • Studies of underlying MB/partonic mechanisms for remaining JM06 phenomenological terms will be carried out. Expected outcome: a) b) MB vertex off-shell behavior → input for lattice simulation(?); Understanding of the transition from MB mechanisms to pD rp GPD’s,/other partonic processes needed for N* studies at high Q2. V.I.Mokeev N* Analysis Workshop’ 20 What mechanisms behind JM06 phenomenological terms? JM06 phenomenological terms will be replaced by MB amplitudes, derived from modern effective Lagrangians of the outlined approach + residual phenomenological contributions, if any. S.Capstick, T.-S.H.Lee, A. Kiswandhi model For particular mechanisms isolated in JM06 the sum is rather limited V.I.Mokeev N* Analysis Workshop’ 21 Conclusions. • Considerable extension of the data on 2p photo- and electro- production from recent experiments, carried out worldwide on continues beams with 4p detectors, open up new opportunities for N* studies. Global analysis of full set of unpolarized observables for the first time available from CLAS, allowed us to develop the JM06 model with most complete accounting for all significant mechanisms. These studies demonstrated capability to map-out all sizeable mechanisms from the fit of various observables combined. The amplitudes, determined for all contributing mechanisms, provide necessary input for extraction of N* parameters in the cc analyses. • Global analysis of observables from major photo- / electro- production channels combined, implementing unitarity within the framework of most advanced Argonne-Osaka approach, offers promising way for credible N*/non-resonant processes separation. Therefore, all necessary tools are available to extract reliable values of N* electrocouplings, at various photo virtualities Q2 and to improve knowledge of N* hadronic parameters. • 2p exclusive channels offer very reach information both on resonant and nonresonant processes, vital for modern hadronic physics. Wealthy of this information may be accessed only in combined efforts, including phenomenological mapping of contributing mechanisms, comprehensive FSI treatment and the studies of actual mechanisms behind phenomenology within the framework of meson-baryon and partonic degrees of freedom. V.I.Mokeev N* Analysis Workshop’ 22 BACK-UP V.I.Mokeev N* Analysis Workshop’ 23 Modeling of 2p production by tree level meson-baryon diagrams. • Set of tree level meson-baryon diagrams. Particular meson and baryon states were implemented based on: a) manifestation of unstable particles in invariant mass distributions; b) established in analysis 1p production and experiments with pion beams; c) needs to improve description of particular data features. • Full sets of diagrams were created, applying all possible permutations for meson/baryon legs V.I.Mokeev N* Analysis Workshop’ 24 Fit of E94-005 CLAS 2p data (L.Elouadrhiri, G.Fedotov, et. al.) collected at low W&Q2 within the framework of JM05 model. full p-D++ p+D 0 2p direct JM05 succeeded to describe p+p, p-p+ p-p mass and p- angular distributions, Failure in description of p+ and pf angular distributions, revealed necessity to modify direct 2p production mechanisms. V.I.Mokeev N* Analysis Workshop’ 25 General problems of MB approaches. • Available MB models are unable to establish all significant mechanisms contributing to the 2p production due to lack of guidance from fundamental theory and insufficient amount of analyzed observables to determine complexity of contribution processes from the data fit. • Most of MB vertex function are unknown and may be only fitted to the data. • FSI were either neglected or treated in oversimplified approximations. Comprehensive approach for description of FSI complexity in the 3 body ppN final state was needed. Such approach has been developed just recently by Argonne-Osaka collaboration (see T-S.H.Lee talk, hepth/0608051). Neither of MB approaches was ever used to extract N* parameters from the 2p photo and electroproduction data. V.I.Mokeev N* Analysis Workshop’ 26 An additional contact terms in pD channels needed to fit data. M g t g ( A (W ) U D g U p Pp + B (W ) U D g U p ( 2 Pp - Pg )) 1 t- 2 2 = 1.64 GeV t ( Pg - Pp ) 2 2 V.I.Mokeev N* Analysis Workshop’ 27 The amplitudes for gpp+F015(1685) and gpp-P++33(1600) channels. 2 g M A (W , Q ) U p g U p ( PF 15 Pp + ) exp 1 2 g M A (W , Q ) U p g U p exp 2 t m p* 2 ( M M ) F 15 p p 2 F 15 2 1 ( M p - p - M P 33 ) 2 P 33 Pp Pp V.I.Mokeev N* Analysis Workshop’ 28 Fit of single differential cross-sections from E93-006 experiment within the framework of JM05. Full calculations gpp-D++ gpp+D0 gpp+D13(1520) gprp gpp-P33++(1640) gpp+F150(1685) direct 2p production V.I.Mokeev N* Analysis Workshop’ 29 Selected p-p+p cross-sections calculated within the framework of JM05, most closed to the E93-006 CLAS data. p+ p, p- p+, p -p invar. masses and p- angular distributions were fitted within the framework of JM05 (V.Mokeev et.al. , Proc. of NSTAR2005 Workshop, p.47) Q2=0 65GeV2 experimetal data from M.Ripani et. al. , Phys. Rev. Lett.91, 022002 (2003) W-interv., GeV 2 thresh. 1.41-1.54 2.45 1.56-1.64 2.19 1.66-1.76 2.04 1.79-1.89 2.06 Q2=0 95GeV2 V.I.Mokeev N* Analysis Workshop’ Q2=1 30 GeV2 30 Evidence for complementary contributions to pD isobar channels. W=1.76 GeV Q2=0.95 GeV2 extra contact term in pD channels on off gp→p+D0: ds/dM, mcbn/GeV JM05 full: p+D0 extra contact term in pD channels on off W=1.81 GeV Q2=0.95 GeV2 p+p mass, GeV V.I.Mokeev N* Analysis Workshop’ p-p mass, GeV 32 Manifestation of gp→p-P33++(1640) and gp→p+F15(1685) isobar channels. W=1.89 GeV Q2=0.95 GeV2 JM05 full p-P33++(1640) and p+F15 (1685) isobar channels off gp→p+F15(1685) gp→p-P 33(1640) Contribution from isobar channels: p-P33++(1640) p+F15 (1685) V.I.Mokeev N* Analysis Workshop’ 33 Resonant/non-resonant mechanism separation. full JM06 calculations non-resonant part resonant part Combined fit of all unpolarized 1-diff. cross-sections allows us to isolate resonant/non-resonant parts, exploiting difference in shapes of their cross-sections. V.I.Mokeev N* Analysis Workshop’ 34 Total p-p+p cross-sections calculated within the framework of JM06, most closed to the preliminary CLAS data at 0.25<Q2<0.60 GeV2 and W<1.57 GeV. preliminary CLAS data, exper. E94-005, L.Elouadrhiri, G.Fedotov, et.al. Q2-interv., GeV2 2 thresh. 0.250-0.400 2.80 0.400-0.500 1.80 0.500-0.600 1.70 V.I.Mokeev N* Analysis Workshop’ 35 High lying N* electrocouplings. D33(1700), P13(1720) resonances mostly decay with 2p emission. 1p data do not have enough sensitivity to these states. First preliminary data on Q2 -evolution of S31(1620), D13(1700), D33(1700), P13(1720) electromagnetic form factors were obtained from analysis of CLAS E93-006 experiment on 2p electroproduction. D33(1700) P13(1720) V.I.Mokeev N* Analysis Workshop’ D33(1700) P13(1720) 36