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Aceti, F., & Oset, E. (2012). Wave functions of composite hadron states and relationship to couplings of scattering amplitudes for general partial waves. Phys. Rev. D, 86(1), 014012–12pp.
Abstract: In this paper we present the connection between scattering amplitudes in momentum space and wave functions in coordinate space, generalizing previous work done for s-waves to any partial wave. The relationship to the wave function of the residues of the scattering amplitudes at the pole of bound states or resonances is investigated in detail. A sum rule obtained for the couplings provides a generalization to coupled channels, any partial wave and bound or resonance states, of Weinberg's compositeness condition, which was only valid for weakly bound states in one channel and s-wave. An example, requiring only experimental data, is shown for the rho meson indicating that it is not a composite particle of pi pi and K (K) over bar but something else.
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Ikeno, N., Molina, R., & Oset, E. (2022). Zcs states from the D*s over bar D* and J=psi K* coupled channels: Signal in B+ -> J=psi phi K+ decay. Phys. Rev. D, 105(1), 014012–13pp.
Abstract: We study the D*s over bar D* system in connection with the J=psi K* in coupled channels and observe that, within reasonable values of the cutoff used to regularize the loops, the system does not develop a bound state. However, the JP = 2+ channel has enough attraction to create a strong cusp structure that shows up in the J=psi K+ invariant mass distribution in the B+ -> J=psi phi K+ decay at the D*s over bar D* threshold. Such structure is results should stimulate further measurements around this region, given the fact that cusp effects provide as valuable information on hadron dynamics as resonances themselves.
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Molina, R., Branz, T., & Oset, E. (2010). New interpretation for the D*(s2)(2573) and the prediction of novel exotic charmed mesons. Phys. Rev. D, 82(1), 014010–17pp.
Abstract: In this manuscript we study the vector-vector interaction within the hidden-gauge formalism in a coupled channel unitary approach. In the sector C = 1, S = 1, J = 2 we get a pole in the T matrix around 2572 MeV that we identify with the D*(s2)(2573), coupling strongly to the D*K*(D-s(*)phi(omega)) channels. In addition we obtain resonances in other exotic sectors which have not been studied before such as C = 1, S = -1, C = 2, S = 0 and C = 2, S = 1. These "flavor-exotic'' states are interpreted as D*(K) over bar*, D*D*, and (DsD)-D-** molecular states but have not been observed yet. In total we obtain nine states with different spin, isospin, charm, and strangeness of non-C = 0, S = 0 and C = 1, S = 0 character, which have been reported before.
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Roca, L., & Oset, E. (2010). Asymmetry observables in e(+)e(-) -> pi(+) pi(-) gamma in the phi region within a chiral unitary approach. Phys. Rev. D, 81(1), 014010–8pp.
Abstract: We make a theoretical study of the charge and forward-backward pion asymmetries in the e(+)e(-) -> pi(+) pi(-) gamma process on and off the phi resonance energy. These observables are rather sensitive to the inner details of the theoretical models to describe the reaction. In addition to the standard implementation of the initial state radiation and the bremsstrahlung contribution to the final state radiation, we use the techniques of the chiral unitary approach to evaluate the contribution from the mechanisms of phi decay into pi(+) pi(-) gamma. This contribution involves the implementation of final state interaction from direct chiral loops, the exchange of vector and axial-vector resonances and the final state interaction through the consideration of the meson-meson unitarized amplitudes, which were found important in a previous work describing the phi -> pi pi gamma. We find a good reproduction of the experimental data from KLOE for the forward-backward asymmetry, both at the phi peak and away from it. We also make predictions for the angular distributions of the charge asymmetry and show that this observable is very sensitive to the chiral loops involved in phi radiative decay.
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Albaladejo, M., & Oset, E. (2013). Combined analysis of the pn -> d pi(+)pi(-) and pn -> pn pi(+)pi(-) cross sections and implications for the interpretation of the pn -> d pi(+)pi(-) data. Phys. Rev. C, 88(1), 014006–6pp.
Abstract: We use recent data that show a narrow peak around root s = 2.37 GeV in the pn -> d pi(+)pi(-) cross section, with about double strength at the peak than in the analogous pn -> d pi(0)pi(0) reaction, and, assuming that it is due to the excitation of a dibaryon resonance, we evaluate the cross section for the pn -> pn pi(+)pi(-) reaction, with the final pn unbound but with the same quantum numbers as the deuteron. We use accurate techniques to determine the final state interaction in the case of the pn forming a deuteron or a positive energy state, which allow us to get the pn -> pn pi(+)pi(-) cross section with pn in I = 0 and S = 1, that turns out to be quite close or saturates the experimental pn -> pn pi(+)pi(-) total cross section around root s = 2.37 GeV, depending on the angular momentum assumed. This poses problems to the assumption of the dibaryon hypothesis, which could be rendered more restrictive with future precise data on the pn -> pn pi(+)pi(-) reaction.
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