2,252 research outputs found
Accurate nucleon electromagnetic form factors from dispersively improved chiral effective field theory
We present a theoretical parametrization of the nucleon electromagnetic form
factors (FFs) based on a combination of chiral effective field theory and
dispersion analysis. The isovector spectral functions on the two-pion cut are
computed using elastic unitarity, chiral pion-nucleon amplitudes, and timelike
pion FF data. Higher-mass isovector and isoscalar t-channel states are
described by effective poles, whose strength is fixed by sum rules (charges,
radii). Excellent agreement with the spacelike proton and neutron FF data is
achieved up to Q^2 \sim 1 GeV^2. Our parametrization provides proper
analyticity and theoretical uncertainty estimates and can be used for low-Q^2
FF studies and proton radius extraction.Comment: 5 pages, 3 figures, 2 table
On the \phi(1020)f_0(980) S-wave scattering and the Y(2175) resonance
We have studied the \phi(1020)f_0(980) S-wave scattering at energies around
threshold employing chiral Lagrangians coupled to vector mesons through minimal
coupling. The interaction kernel is obtained by considering the f_0(980) as a
K\bar{K} bound state. The Y(2175) resonance is generated in this approach by
the self-interactions between the \phi(1020) and the f_0(980) resonances. We
are able to describe the e^+e^-\to \phi(1020)f_0(980) recent scattering data to
test experimentally our scattering amplitudes, concluding that the Y(2175)
resonance has a large \phi(1020)f_0(980) meson-meson component.Comment: 20 pages, 8 figure
Nuclear matter from the ladder resummation in terms of the experimental nucleon-nucleon scattering amplitudes
Infinite nuclear matter is studied by resuming the series of ladder diagrams
based on the results developed by us in Ann. Phys. 437, 168741 (2022). The
master formula for the energy density is explicitly solved for the case of
contact interactions, within a pionless description of the nucleon-nucleon
interactions. Renormalized results are obtained which are directly expressed in
terms of the nucleon-nucleon phase shifts and mixing angles in partial-wave
amplitudes up to an including waves, with convergence reached under the
inclusion of higher partial waves. The energy per particle, density and sound
velocity resulting from the ladder series are given for symmetric and neutron
matter. This resummation of the ladder diagrams provides a rigorous result that
may be used as low-density reference for other parameterizations of
for higher densities.Comment: 29 pages, 9 figure
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