0000000000093041
AUTHOR
Enrique Ruiz Arriola
showing 9 related works from this author
Bethe-Salpeter Approach for Meson-Meson Scattering in Chiral Perturbation Theory
1998
The Bethe-Salpeter equation restores exact elastic unitarity in the s- channel by summing up an infinite set of chiral loops. We use this equation to show how a chiral expansion can be undertaken by successive approximations to the potential which should be iterated. Renormalizability of the amplitudes in a broad sense can be achieved by allowing for an infinite set of counter-terms as it is the case in ordinary Chiral Perturbation Theory. Within this framework we calculate the $\pi \pi$ scattering amplitudes both for s- and p-waves at lowest order in the proposed expansion where a successful description of the low-lying resonances ($\sigma$ and $\rho$) and threshold parameters is obtained.…
Meson dominance of hadron form factors and large-Ncphenomenology
2012
We discuss the pion and nucleon form factors and generalized form factors within the large-Nc approach in the space-like region. We estimate their theoretical uncertainties through the use of the half-width rule, amounting to taking the half-width of the resonances as the deviation of their mass parameters. The approach embodies the meson dominance of form factors and the high-energy constraints from perturbative QCD. We compare the results with the available experimental data and lattice simulations. The meson-dominance form factors are generally comparable to the available experimental data within the half-width-rule uncertainties. Our errors are comparable to the experimental uncertainti…
Hadron form factors and large-Nc phenomenology
2014
The half width rule provides a way to consider 1/Nc corrections to hadronic models containing resonances. Consequences of such ideas for hadron form factors and Regge trajectories are explored, with special emphasis on the possibility to describe the spectrum of light and heavy unflavored vector mesons in a universal way.
Reply to "Comment on 'Systematics of radial and angular-momentum Regge trajectories of light non-strange qqbar-states' "
2013
In his Comment, D. Bugg argues against our usage of the PDG collection of light non-strange states together with the half-width rule to analyze the linearity of radial and angular-moment Regge trajectories in the large-N_c limit. After taking into account his observations on our choice of data, the radial Regge trajectories are again analyzed. We still find that our conclusion on the lack of universality between radial- and angular-momentum Regge trajectories is valid.
S-11-N(1535) and -N(1650) resonances in meson-baryon unitarized coupled channel chiral perturbation theory
2001
The s-wave meson-baryon scattering is analyzed for the strangeness S = 0 sector in a Bethe-Salpeter coupled channel formalism incorporating chiral symmetry. Four channels have been considered: piN, etaN, K Lambda, K Sigma. The needed two-particle irreducible matrix amplitude is taken from lowest order chiral perturbation theory in a relativistic formalism and low energy constants are fitted to the elastic piN phase shifts and the pi (-) p-->etan and pi (-) p-->K-0 Lambda cross section data. The position of the complex poles in the second Riemann sheet of the scattering amplitude determines masses and widths of the S-11-N(1535) and -N(1650) resonances, in reasonable agreement with experiment…
S=-1 meson-baryon unitarized coupled channel chiral perturbation theory and the S-01 resonances Lambda(1405) and -Lambda(1670)
2003
The s-wave meson-baryon scattering is analyzed for the strangeness S=-1 and isospin I=0 sector in a Bethe-Salpeter coupled channel formalism incorporating chiral symmetry. Four channels have been considered: piSigma, (K) over barN, etaLambda, and KXi. The required input to solve the Bethe-Salpeter equation is taken from lowest order chiral perturbation theory in a relativistic formalism. There appear undetermined low energy constants, as a consequence of the renormalization of the amplitudes, which are obtained from fits to the piSigma-->piSigma mass spectrum, to the elastic (K) over barN-->(K) over barN and (K) over barN-->piSigma t matrices and to the K(-)p-->etaLambda cross section data.…
Large-N(C) properties of the rho and f(0)(600) mesons from unitary resonance chiral dynamics
2011
We construct pi-pi amplitudes that fulfill exact elastic unitarity, account for one loop Chiral Perturbation Theory contributions and include all 1/Nc leading terms, with the only limitation of considering just the lowest-lying nonet of exchanged resonances. Within such scheme, the Nc dependence of sigma and rho masses and widths is discussed. Robust conclusions are drawn in the case of the rho resonance, confirming that it is a stable meson in the limit of a large number of QCD colors, Nc. Less definitive conclusions are reached in the scalar-isoscalar sector. With the present quality of data, we cannot firmly conclude whether or not the Nc=3 f0(600) resonance completely disappears at larg…
Bethe-Salpeter approach for the P-33 elastic pion-nucleon scattering in heavy baryon chiral perturbation theory
2001
Heavy baryon chiral perturbation theory (HBChPT) to leading order provides a kernel to solve the Bethe-Salpeter equation for the P-33 [Delta (1232)-channel] pi -N system, in the infinite nucleon mass limit. Crossed Born terms include, when iterated within the Bethe-Salpeter equation, both all one- and some two-pion intermediate states, hence preserving elastic unitarity below the two-pion production threshold. This suggests searching for a solution with the help of dispersion relations and suitable subtraction constants, when all in-elasticities are explicitly neglected. The solution allows for a successful description of the experimental phase shift from threshold Lip to roots = 1500 MeV i…
Properties of the rho and sigma mesons from unitary chiral dynamics
2009
The chiral limit of the rho and sigma masses and widths is discussed. We work within the inverse amplitude method to one loop in SU(2) chiral perturbation theory and analyze the consequences that all chiral logarithms cancel out in the rho channel, while they do not cancel for the sigma case, and how they strongly influence the properties of this latter resonance. Our results confirm and explain the different behavior of the sigma and rho poles for N(C) not far from 3, but we extend the analysis to very large N(C), where the behavior of these two resonances is reanalyzed. We note that the rather natural requirement of consistency between resonance saturation and unitarization imposes useful…