DMT model for pN scattering and pion e.m. production Shin Nan Yang National Taiwan University - PowerPoint PPT Presentation

Loading...

PPT – DMT model for pN scattering and pion e.m. production Shin Nan Yang National Taiwan University PowerPoint presentation | free to view - id: 6fe1ba-NjUzM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

DMT model for pN scattering and pion e.m. production Shin Nan Yang National Taiwan University

Description:

Title: Some recent advances in nucleon structure study Shin Nan Yang National Taiwan University Author: YANG Last modified by: LT Created Date – PowerPoint PPT presentation

Number of Views:43
Avg rating:3.0/5.0
Slides: 33
Provided by: YANG147
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: DMT model for pN scattering and pion e.m. production Shin Nan Yang National Taiwan University


1
DMT model for pN scattering and pion e.m.
productionShin Nan YangNational Taiwan
University
Dubna Kamalov Mainz Drechsel, Tiator Taipei
Guan Yeu Chen, SNY
EBAC discussion meeting, Jlab, May 24-26, 2010.
2
Motivation
  • To construct a meson-exchange model forpN
    scattering
  • and e.m. production of pion so that a
    consistent
  • extraction of the resonance properties like,
    mass, width,
  • and form factors, from both reactions can be
    achieved.
  • Comparison with LQCD results requires reliable
  • extraction.
  • consistent extractions ? minimize model
    dependence?
  • The resonances we study are always of the type
    which
  • results from dressing of the quark core by
    meson cloud.
  • ? understand the underlying structure and
    dynamics

3
Taipei-Argonne pN model meson-exchange ? N
model below 400 MeV
4
Three-dimensional reduction
Cooper-Jennings reduction scheme
5
Choose to be given by
6
C.T. Hung, S.N. Yang, and T.-S.H. Lee, Phys. Rev.
C64, 034309 (2001)
7
DMT pN modelextension of Taipei-Argonne model
to energies ? 2 GeV
  • Inclusion of ?N channel in S11
  • Introduce higher resonances as
  • indicated by the data

G.Y. Chen et al., Phys. Rev. C 76 (2007) 035206.
8
Inclusion of ?N channel in S11
9
(No Transcript)
10
Introduction of higher resonances
  • If there are n resonances, then
  • How does one extract masses,
  • widths et al. of the resonances?

Coupled-channels equations can be solved
11
How does one extract masses, widths et al. of
the resonances?
  • Two schemes to separate the total
  • t- matrix into background and
  • resonance contribution
  • Afnan et al. and Sato-Lee
  • Dubna-Mainz-Taipei (DMT)

12
Sato-Lees separation method
Unitary with phase dB
Self-energy
13
Self-energy SR(E)
14
Extension of SLs method to n resonances
15
DMTs decomposition of bkg and reson.
With only one resoance,
Note that both tB and tR have the same phase of
16
Extension of DMTs method to n resonances
17
It can be shown,
contains contribution of Ri excitation
18
Remark the background in our separation,
already does contain some resonance contributions
and in the calculation of the residues, the full
t-matrix has to be employed.
19
Dynamical model for ? N ? ? N
To order e, the t-matrix for ? N ? ? N is
written as
two ingredients
v?k , tkN
Both on- off-shell
20
  • Multipole decomposition of gives the physical
    amplitude in channel ?(? , l? , j), (with ? N
    intermediate states neglected)
  • where
  • ?(?), R(?) ? N scattering phase shift and
    reaction matrix in channel ?
  • k k, qE photon and pion on-shell momentum

21
both tB and tR satisfy Fermi-Watson
theorem, respectively.
22
DMT Model
23
Dubna-Mainz-Taipei (DMT)
24
SLs decomposition of bkg and reson.
DMT, bare
dressed
25
  • In DMT, we approximate the resonance contribution
    AR?(W,Q2) by the following Breit-Wigner form
  • with
  • f? R Breit-Wigner factor describing the
    decay of the resonance R
  • ?R (W) total width
  • MR physical mass
  • (W) to adjust the phase of the total
    multipole to be equal to the
  • corresponding ? N phase shift ?
    (?).
  • Note that

26
Efforts are being undertaken to use the dressed
propagators and vertices obtained in DMT pN model
to achieve consistency in the analyses ofpN and
p-production.
27
Results of DMT model near threshold,
28
M. Weis et al., Eur. Phys. J. A 38 (2008) 27
29
Photon Beam Asymmetry near Threshold
Data A. Schmidt et al., PRL 87 (2001) _at_
MAMI DMT S. Kamalov et al., PLB 522 (2001)
30
D. Hornidge (CB_at_MAMI) private communication
PRELIMINARY
31
D. Hornidge (CB_at_MAMI) private communication
PRELIMINARY
32
D. Hornidge (CB_at_MAMI) private communication
PRELIMINARY
About PowerShow.com