30 research outputs found
Study of nucleon resonances at EBAC@JLab
We present the dynamical origin of the P11 nucleon resonances resulting from
a dynamical coupled-channels (DCC) analysis of meson production reactions off a
nucleon target, which is conducted at Excited Baryon Analysis Center (EBAC) of
Jefferson Lab. Two resonance poles are found in the energy region where the
Roper resonance P11(1440) was identified. Furthermore, the two resonance poles
and the next higher resonance pole corresponding to P11(1710) are found to
originate from a single bare state.Comment: Contribution to 7th Japan-China Joint Nuclear Physics Symposium,
Tsukuba, Nov. 9-13, 2009. 5 pages, 2 figure
Off-Shell Extension of the Chiral Reduction Formula
We present a proper off-mass-shell extension of the chiral reduction formula
(CHRF) proposed by Yamagishi and Zaned. This is achieved by rewriting the CHRF
in a manifestly consistent form with the conventional LSZ reduction formula.Comment: v.2. 16 pages; v.3. 11 pages, Version to apper in Prog. Theor. Phy
An Alternative View of the Dynamical Origin of the P11 Nucleon Resonances: Results from the Excited Baryon Analysis Center
We present an alternative interpretation for the dynamical origin of the P11
nucleon resonances, which results from the dynamical coupled-channels analysis
at Excited Baryon Analysis Center of Jefferson Lab. The results indicate the
crucial role of the multichannel reaction dynamics in determining the N^*
spectrum.Comment: 3 pages, 1 figure. Contribution to the proceedings of the 19th
Particles and Nuclei International Conference (PANIC11), Cambridge, MA, USA,
July 24-29, 201
Extraction of nucleon resonances from global analysis of meson production reactions at EBAC
We report the current status of exploring the dynamical aspect of the excited
nucleon states through the comprehensive coupled-channels analysis of meson
production reactions at the Excited Baryon Analysis Center of Jefferson Lab.Comment: 4 pages, 3 figures, Contribution to the proceedings of International
conference on the structure of baryons (BARYONS'10), Osaka, Japan, Dec. 7-11,
201
Master formula approach to broken chiral U(3)xU(3) symmetry
The master formula approach to chiral symmetry breaking proposed by Yamagishi
and Zahed is extended to the U_R(3)xU_L(3) group, in which effects of the
U_A(1) anomaly and the flavor symmetry breaking m_u \not= m_d \not= m_s are
properly contained. New identities for the gluon topological susceptibility and
pi^0, eta, eta' -> gamma^(*) gamma^(*) decays are derived, which exactly embody
the consequence from broken chiral symmetry in QCD without relying on any
unphysical limit.Comment: Version to appear in PRD, 25 page