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Hiroyuki Kamano (RCNP, Osaka Univ.)

Dynamical coupled-channels a pproach to meson p roduction r eactions in the N * region and its application to neutrino-nucleon/nucleus reactions. Hiroyuki Kamano (RCNP, Osaka Univ.). Seminar at J-PARC, March 19, 2012. Experimental developments.

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Hiroyuki Kamano (RCNP, Osaka Univ.)

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  1. Dynamical coupled-channels approach to meson production reactions in the N* region and its application to neutrino-nucleon/nucleus reactions Hiroyuki Kamano (RCNP, Osaka Univ.) Seminar at J-PARC, March 19, 2012

  2. Experimental developments Since the late 90s, huge amount of high precision data of meson photo-production reactionson the nucleon target has been reported from electron/photon beam facilities. JLab, MAMI, ELSA, GRAAL, LEPS/SPring-8, … Opens a great opportunity to make quantitative study of the N* states !! E. Pasyuk’stalk at Hall-B/EBAC meeting

  3. Dynamical coupled-channels analysis ofmeson production reactions H. Kamano (RCNP), T.-S. H. Lee (ANL), S. Nakamura (JLab), T. Sato (Osaka U./KEK) B. Julia-Diaz (Barcelona U.), A. Matsuyama (Shizuoka U.), N. Suzuki (Osaka U.) • Objectives and goals: • Through the comprehensive analysis • of world dataof pN, gN, N(e,e’) reactions, • Determine N* spectrum (pole masses) • Extract N* form factors (e.g., N-N* e.m. transition form factors) • Provide reaction mechanism information necessary forinterpreting N* spectrum, structures and dynamical origins Reaction Data Analysis Based on Reaction Theory Spectrum, structure,… of N* states Hadron Models Lattice QCD QCD

  4. Dynamical coupled-channels model for meson production reactions N* spectrum, structure, … Meson production data Reaction dynamics Dynamical coupled-channels model of meson production reactions A. Matsuyama, T. Sato, T.-S.H. Lee Phys. Rep. 439 (2007) 193 • a • a Singular!

  5. Hadronic amplitudes in the DCC model For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) Amplitudes of two-body meson-baryon reactions M M’ M M’ + B B’ B’ B Non-resonant amp. Rsonant amp. Reaction channels:

  6. Hadronic amplitudes in the DCC model For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) M M’ M M’ + u-channel s-channel B B’ B’ B Meson-Baryon Green functions N Exchange potentials N, D Non-resonant amp. Rsonant amp. t-channel contact Stable channels p, r, s, w,.. M’’ + = N p D p r,s B’’ N “Z-diagrams” D p D N D D r, s … p p + + + = p Quasi 2-bodychannels p p r, s p ~ 150 Feynman diagrams N N Produce 2-body and 3-body ppN cutsrequired by the unitarity!!

  7. Hadronic amplitudes in the DCC model For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) M M’ M M’ + B B’ B’ B Non-resonant amp. Rsonant amp. M’’ + = B’’ … + + + =

  8. + = + = Hadronic amplitudes in the DCC model For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) M M’ M M’ + B B’ B’ B Non-resonant amp. Rsonant amp. Dressed N*-MB vertex Dressed N* propagator Non-resonant amp. Bare propagator (Bare mass) Meson cloud Bare vertex Self energy Effects of rescattering processes (reaction dynamics) are included consistentlywith the unitarityof S-matrix.

  9. Electromagnetic amplitudes in the DCC model For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) E.M. current interactions are treated perturbatively. g g M’ M’ + B B’ B’ B Non-resonant amp. Rsonant amp. Rescattering effect + = Rescattering effect = + Dressed gN N* vertex Bare vertex

  10. DCC analysisof meson production reactions (current status) Fully combinedanalysis of gN , N  N , hN , KL, KSreactions !! 2010 ~ 2012 7 channels (pN,hN,pD,rN,sN,KL,KS) < 2.1 GeV < 2 GeV < 2 GeV < 2 GeV < 2.2 GeV < 2.2 GeV 2006 ~ 2009 5 channels (pN,hN,pD,rN,sN) < 2 GeV < 1.6 GeV < 2 GeV ― ― ― • # of coupled channels • p  N • gp N • -p hn • gphp • ppKL, KS • gpKL,KS Kamano, Nakamura, Lee, Sato (2012)

  11. Analysis Database Pion-induced reactions (purely strong reactions) ~ 28,000 data points to fit Photo- production reactions

  12. Partial wave amplitudes of pi N scattering Real part Kamano, Nakamura, Lee, Sato 2012 Previous model (fitted to pN  pN dataonly) [PRC76 065201 (2007)] Imaginary part

  13. Pion-nucleon elastic scattering Angular distribution Target polarization 1234 MeV 1449 MeV 1678 MeV 1900 MeV Kamano, Nakamura, Lee, Sato, 2012

  14. pi N  MB reactions Kamano, Nakamura, Lee, Sato, 2012 1732 MeV 1757 MeV 1792 MeV 1845 MeV 1879 MeV 1879 MeV 1985 MeV 1966 MeV 1966 MeV 2031 MeV 2059 MeV 2059 MeV

  15. pi N  pi pi N reaction Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC79 025206 (2009) Parameters used in the calculation are from pN  pN analysis. s (mb) W (GeV) Full result C. C. effect off Full result Phase space Data handled with the help of R. Arndt

  16. Single pion photoproduction Kamano, Nakamura, Lee, Sato, 2012 Angular distribution Photon asymmetry 1137 MeV 1137 MeV 1232 MeV 1232 MeV 1334 MeV 1334 MeV 1462 MeV 1462 MeV 1527 MeV 1527 MeV 1617 MeV 1617 MeV 1729 MeV 1729 MeV 1834 MeV 1834 MeV 1958 MeV 1958 MeV Previous model (fitted to gN  pN data up to 1.6 GeV) [PRC77 045205 (2008)] Kamano, Nakamura, Lee, Sato, 2012

  17. Kamano, Nakamura, Lee, Sato 2012

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  20. Kamano, Nakamura, Lee, Sato 2012

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  23. Parameters used in the calculation are from pN  pN & gN  pN analyses. Double pion photoproduction Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC80 065203 (2009) • Good description near threshold • Reasonable shape of invariant mass distributions • Above 1.5 GeV, the total cross sections of p00 and p+- overestimate the data.

  24. Single pion electroproduction (Q2 > 0) Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, PRC80 025207 (2009) Fit to the structure function data (~ 20000) from CLAS p (e,e’ p0) p W < 1.6 GeV Q2 < 1.5 (GeV/c)2 is determined at each Q2. g q (q2 = -Q2) N N* N-N* e.m. transition form factor

  25. Meson cloud effect in gamma N  N* form factors GM(Q2) for g N  D (1232) transition N, N* Full Bare Note: Most of the available static hadron models give GM(Q2) close to “Bare” form factor.

  26. How to extend the DCC model to neutrino reactions Just replace E.M. current by vector and axial currents. V, A g V, A g M’ M’ + B B’ B’ B Non-resonant amp. Rsonant amp. V, A V, A + = Rescattering effect V, A V, A V, A = + Dressed gN N* vertex Dressed VN or AN  N* vertex Bare vertex

  27. How to extend the DCC model to neutrino reactions What we need to do: Vector part Axial part V, A Ready for neutrino reaction (We can get all isospin components simply by isospin rotation.) Construct AN  MB potential for MB = pD, rN, sN, KL, KS (We already have the potential for MB = pNcase.) For N*s except D(1232), as a first step, we evaluate A N  N* vertices from pNN* couplings by making use of PCAC. Evaluation of g neutron  N* vertices for I = ½ N* states V, A

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