Dai, L. R., & Oset, E. (2020). Helicity amplitudes in the (B)over-bar -> D*(nu)over-bar(tau)tau decay with V-A breaking in the quark sector. Eur. Phys. J. A, 56(5), 154–8pp.
Abstract: In view of the recent measurement of the F-D*(L) magnitude in the (B) over bar -> D*(nu) over bar (tau)tau reaction we evaluate this magnitude within the standard model and for a family of models with the gamma(mu) – alpha gamma(mu)gamma(5) current structure for the quarks for different values of a. At the same time we evaluate also the transverse contributions, M = -1, M = +1, and find that the difference between the M = -1 and M = +1 contributions is far more sensitive to changes in a than the longitudinal component. These findings should be looked as an incentive to measure the transverse helicities which are bound to be a far more sensitive magnitude to possible new physics than F-D*(L).
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Dai, L. R., & Oset, E. (2018). Polarization amplitudes in VP decay beyond the Standard Model. Eur. Phys. J. A, 54(12), 219–10pp.
Abstract: We study the amplitudes of the -VP decay for the different polarizations of the vector meson V, using a formalism where the mapping from the quark degrees of freedom to the meson ones is done with the P-3(0) model. We extend the formalism to a case, with the operator -5, that can account for different models beyond the Standard Model and study in detail the -K*0K- reaction for the different polarizations of the K*0. The results are shown in terms of the parameter that differs for each model. We find that is very different for each of the third components of the vector spin, M=+/- 1,0, and in particular the magnitude |M=-1 is very sensitive to the parameter, which makes the investigation of this magnitude very useful to test different models beyond the Standard Model.
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Dai, L. R., Pavao, R., Sakai, S., & Oset, E. (2019). tau(-) -> nu tau M1 M2, with M1, M2 pseudoscalar or vector mesons. Eur. Phys. J. A, 55(2), 20–22pp.
Abstract: .We perform a calculation of the -M1M2, with M1,M2 either pseudoscalar or vector mesons using the basic weak interaction and angular momentum algebra to relate the different processes. The formalism also leads to a different interpretation of the role played by G-parity in these decays. We also observe that, while PPp-wave production is compatible with chiral perturbation theory and experiment, VP and VVp-wave production is clearly incompatible with experiment and we develop the formalism also in this case, producing the VP or VV pairs in s-wave. We compare our results with experiment and other theoretical approaches for rates and invariant mass distributions and make predictions for unmeasured decays. We show the value of these reactions, particularly if the M1M2 mass distribution is measured, as a tool to learn about the meson-meson interaction and the nature of some resonances, coupling to two mesons, which are produced in such decays.
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Doring, M., Meissner, U. G., Oset, E., & Rusetsky, A. (2011). Unitarized Chiral Perturbation Theory in a finite volume: Scalar meson sector. Eur. Phys. J. A, 47(11), 139–15pp.
Abstract: We develop a scheme for the extraction of the properties of the scalar mesons f(0)(600), f(0)(980), and a(0)(980) from lattice QCD data. This scheme is based on a two-channel chiral unitary approach with fully relativistic propagators in a finite volume. In order to discuss the feasibility of finding the mass and width of the scalar resonances, we analyze synthetic lattice data with a fixed error assigned, and show that the framework can be indeed used for an accurate determination of resonance pole positions in the multichannel scattering.
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Doring, M., Meissner, U. G., Oset, E., & Rusetsky, A. (2012). Scalar mesons moving in a finite volume and the role of partial wave mixing. Eur. Phys. J. A, 48(8), 114–18pp.
Abstract: Phase shifts and resonance parameters can be obtained from finite-volume lattice spectra for interacting pairs of particles, moving with non-zero total momentum. We present a simple derivation of the method that is subsequently applied to obtain the pi pi and pi K phase shifts in the sectors with total isospin I – 0 and I – 1/2, respectively. Considering different total momenta, one obtains extra data points for a given volume that allow for a very efficient extraction of the resonance parameters in the infinite-volume limit. Corrections due to the mixing of partial waves are provided. We expect that our results will help to optimize the strategies in lattice simulations, which aim at an accurate determination of the scattering and resonance properties.
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