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Garzon, E. J., Molina, R., Hosaka, A., & Oset, E. (2014). Strategies for an accurate determination of the X(3872) energy from QCD lattice simulations. Phys. Rev. D, 89(1), 014504–9pp.
Abstract: We develop a method to determine accurately the binding energy of the X( 3872) from lattice data for the D (D) over bar* interaction. We show that, because of the small difference between the neutral and charged components of the X( 3872), it is necessary to differentiate them in the energy levels of the lattice spectrum if one wishes to have a precise determination of the the binding energy of the X( 3872). The analysis of the data requires the use of coupled channels. Depending on the number of levels available and the size of the box, we determine the precision needed in the lattice energies to finally obtain a desired accuracy in the binding energy.
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Garzon, E. J., & Oset, E. (2015). Mixing of pseudoscalar-baryon and vector-baryon in the J(P)=1/2(-) sector and the N* (1535) and N* (1650) resonances. Phys. Rev. C, 91(2), 025201–7pp.
Abstract: We study the meson-baryon interaction with J(P) = 1/2 using the hidden-gauge Lagrangians and mixing pseudoscalar meson-baryon with the vector meson-baryon states in a coupled channels scheme with pi N, eta N, K Lambda, K Sigma, rho N, and pi Delta (d wave). We fit the subtraction constants of each channel to the S-11 partial wave amplitude of the pi N scattering data extracted from the partial wave analysis of the George Washington group. We find two poles that we associate to the N*(1535) and the N*(1650) resonances, with negative subtraction constants of natural size, and compare the results with empirical determinations of these pole positions. We calculate the branching ratios for the different channels of each resonance and we find a good agreement with the experimental data. The cross section for the pi(-)p -> eta n scattering is also evaluated and compared with experiment.
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Garzon, E. J., & Oset, E. (2012). Effects of pseudoscalar-baryon channels in the dynamically generated vector-baryon resonances. Eur. Phys. J. A, 48(1), 5–20pp.
Abstract: We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled-channels unitary approach, including also the pseudoscalar-baryon channels which couple to the same quantum numbers. We examine the scattering amplitudes and their poles, which can be associated to the known J(P) = 1/2(-), 3/2(-) baryon resonances, and determine the role of the pseudoscalar-baryon channels, changing the width and eventually the mass of the resonances generated with only the basis of vector-baryon states.
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Garzon, E. J., & Xie, J. J. (2015). Effects of a Nc(c)over-bar* resonance with hidden charm in the pi(-)p -> D-Sigma(+)(c) reaction near threshold. Phys. Rev. C, 92(3), 035201–4pp.
Abstract: We study the effect of a hidden charm nuclear excited state N-c (c) over bar* in the pi(-)p -> D-Sigma(+)(c) reaction near threshold using an effective Lagrangian approach. We calculate the background contribution of the t and u channels by the D*(0) vector meson exchange and Sigma(++)(c) intermediate state, respectively. We show that the consideration of a N-c (c) over bar* resonance provides an enhancement of the total cross section close to the reaction threshold. We also evaluate the differential cross section for different energies and we study the angle dependence. It is expected that our model calculations will be tested in future experiments.
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Garzon, E. J., Xie, J. J., & Oset, E. (2013). Case in favor of the N*(1700)(3/2(-)). Phys. Rev. C, 87(5), 055204–12pp.
Abstract: Using an interaction extracted from the local hidden-gauge Lagrangians, which brings together vector and pseudoscalar mesons, and the coupled channels rho N (s wave), pi N (d wave), pi Delta (s wave), and pi Delta (d wave), we look in the region ofv root s = 1400-1850 MeV and find two resonances dynamically generated by the interaction of these channels, which are naturally associated to N*(1520)(3/2(-)) and N*(1700)(3/2(-)). N*(1700)(3/2(-)) appears neatly as a pole in the complex plane. The free parameters of the theory are chosen to fit the pi N (d-wave) data. Both the real and imaginary parts of the pi N amplitude vanish in our approach in the vicinity of this resonance, which is similar to what happens in experimental determinations and which makes this signal very weak in this channel. This feature could explain why this resonance does not show up in some experimental analyses, but the situation is analogous to that of the f(0)(980) resonance, the second scalar meson after sigma[f(0)(500)] in the pi pi(d-wave) amplitude. The unitary coupled channel approach followed here, in connectionwith the experimental data, leads automatically to a pole in the 1700-MeV region and makes this second 3/2-resonance unavoidable.
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Martinez Torres, A., Garzon, E. J., Oset, E., & Dai, L. R. (2011). Limits to the fixed center approximation to Faddeev equations: The case of the phi(2170). Phys. Rev. D, 83(11), 116002–9pp.
Abstract: The fixed center approximation to the Faddeev equations has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper, we study the case of the phi(2170), which has been described by means of Faddeev equations as a resonant state of phi and K (K) over bar, and show the problems derived from the use of the fixed center approximation in its study. At the same time, we also expose the limitations of an alternative approach recently proposed.
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Oset, E., Ramos, A., Garzon, E. J., Molina, R., Tolos, L., Xiao, C. W., et al. (2012). Interaction of vector mesons with baryons and nuclei. Int. J. Mod. Phys. E, 21(11), 1230011–18pp.
Abstract: After some short introductory remarks on particular issues on the vector mesons in nuclei, in this paper, we present a short review of recent developments concerning the interaction of vector mesons with baryons and with nuclei from a modern perspective using the local hidden gauge formalism for the interaction of vector mesons. We present results for the vector-baryon interaction and in particular for the resonances which appear as composite states, dynamically generated from the interaction of vector mesons with baryons, taking also the mixing of these states with pseudoscalars and baryons into account. We then venture into the charm sector, reporting on hidden charm baryon states around 4400 MeV, generated from the interaction of vector mesons and baryons with charm, which have a strong repercussion on the properties of the J/Psi N interaction. We also address the interaction of K* with nuclei and make suggestions to measure the predicted huge width in the medium by means of transparency ratio. The formalism is extended to study the phenomenon of J/psi suppression in nuclei via J/psi photo-production reactions.
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Sun, B. X., Garzon, E. J., & Oset, E. (2010). Radiative decay into gamma-baryon of dynamically generated resonances from the vector-baryon interaction. Phys. Rev. D, 82(3), 034028–11pp.
Abstract: We study the radiative decay into gamma and a baryon of the SU(3) octet and decuplet of nine and ten resonances that are dynamically generated from the interaction of vector mesons with baryons of the octet and the decuplet, respectively. We obtain quite different partial decay widths for the various resonances, and for different charge states of the same resonance, suggesting that the experimental investigation of these radiative decays should bring much information on the nature of these resonances. For the case of baryons of the octet we determine the helicity amplitudes and compare them with experimental data when available.
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