35 research outputs found
Electromagnetic properties of the Delta(1232) and decuplet baryons in the self-consistent SU(3) chiral quark-soliton model
We examine the electromagnetic properties of the Delta(1232) resonance within
the self-consistent chiral quark-soliton model. In particular we present the
Delta form factors of the vector-current GE0, GE2 and GM1 for a
momentum-transfer range of . We apply the
symmetry-conserving quantization of the soliton and take 1/N_c rotational
corrections into account. Values for the magnetic moments of all decuplet
baryons as well as for the N-Delta transition are given. Special interest is
also given to the electric quadrupole moment of the Delta.Comment: 24 pages, 8 figure
Photoproduction of the Theta^+ and its vector and axial-vector structure
We present recent investigations on the vector and axial-vector transitions
of the baryon antidecuplet within the framework of the self-consistent SU(3)
chiral quark-soliton model, taking into account the 1/N_c rotational and linear
m_s corrections. The main contribution to the electric-like transition form
factor comes from the wave-function corrections. This is a consequence of the
generalized Ademollo-Gatto theorem. It is also found that in general the
leading-order contributions are almost canceled by the rotational 1/N_c
corrections. The results are summarized as follows: the vector and tensor
K^*-N-Theta coupling constants, g_{K^*-N-Theta}=0.74 - 0.87 and
f_{K^*-N-Theta}=0.53 - 1.16, respectively, and Gamma_{Theta->KN}=0.71 MeV,
based on the result of the K-N-Theta coupling constant g_{K-n-Theta}=0.83. We
also show the differential cross sections and beam asymmetries, based on the
present results. We also discuss the connection of present results with the
original work by Diakonov, Petrov, and Polyakov.Comment: 9 pages, 6 figures, An invited talk given at the Workshop of Excited
Nucleon - NSTAR2009 held in Beijing, April 19-22 200
Coarse graining ππ scattering
We carry out an analysis of ππ scattering in the
I J = 00, 11 and 20 channels in configuration space up to
a maximal center-of-mass energy
√
s = 1.4 GeV. We separate
the interaction into two regions marked by an elementarity
radius of the system; namely, a long distance region
above which pions can be assumed to interact as elementary
particles and a short distance region where many physical
effects cannot be disentangled. The long distance interaction
is described by chiral dynamics, where a two-pionexchange
potential is identified, computed and compared to
lattice calculations. The short distance piece corresponds to
a coarse grained description exemplified by a superposition
of delta-shell potentials sampling the interaction with the
minimal wavelength. We show how the so constructed nonperturbative
scattering amplitude complies with the proper
analytic structure, allowing for an explicit N/D type decomposition
in terms of the corresponding Jost functions and
fulfilling dispersion relations without subtractions. We also
address renormalization issues in coordinate space and investigate
the role of crossing when fitting the scattering amplitudes
above and below threshold to Roy-equation results. At
higher energies, we show how inelasticities can be described
by one single complex and energy dependent parameter. A
successful description of the data can be achieved with a
minimal number of fitting parameters, suggesting that coarse
graining is a viable approach to analyze hadronic processes.Work partially supported by Spanish MINEICO and European FEDER
funds (grants FIS2014-59386-P, FIS2017-85053-C2-1-P and FPA2015-
64041-C2-1-P), Junta de Andalucía (grant FQM-225) and the Swiss
National Science Foundation
Heavy-quark-mass expansion of vector and tensor currents and intrinsic charm in nucleon form factors
Mass splittings of the baryon decuplet and antidecuplet with the second-order flavor symmetry breakings within a chiral soliton model
We revisit the mass splittings of SU(3) baryons, taking into account the
second-order effects of isospin and SU(3) flavor symmetry breakings within the
framework of a chiral soliton model. The masses of the baryon decuplet turn out
to be improved, compared to those with the first-order corrections. The mass of
the N^* as a member of the baryon antidecuplet is obtained as M_{n^*}=1687 MeV,
which is in agreement with the recent experimental data. The pion-nucleon sigma
term becomes \Sigma_{\pi N}=(50.5\pm 5.4) MeV.Comment: 9 pages. No figure. arXiv admin note: substantial text overlap with
arXiv:1010.379
Transversity in hard exclusive electroproduction of pseudoscalar mesons
Estimates for electroproduction of pseudoscalar mesons at small values of
skewness are presented. Cross sections and asymmetries for these processes are
calculated within the handbag approach which is based on factorization in hard
parton subprocesses and soft generalized parton distributions (GPDs). The
latter are constructed from double distributions. Transversity GPDs are taken
into account; they are accompanied by twist-3 meson wave functions. For most
pseudoscalar-meson channels a combination of H-tilde_T plays a
particularly prominent role. This combination of GPDs which we constrain by
moments obtained from lattice QCD, leads with the exception of the pi+ and eta'
channels, to large transverse cross sections.Comment: 36 pages and 27 figure