arXiv subjects

G. Galatà

Publications and source records attributed to G. Galatà.

4 recordsLinked to original sources

arXiv2016

Strong decays of baryons and missing resonances

We provide results for the open-flavor strong decays of strange and non-strange baryons into a baryon-vector/pseudoscalar meson pair. The decay amplitudes are computed in the $^3P_0$ pair-creation model, where $s\bar{s}$ pair-creation suppression is included for the first time in the baryon sector, in combination with the U(7) and hypercentral models. The effects of this $s\bar{s}$ suppression mechanism cannot be re-absorbed in a redefinition of the model parameters or in a different choice of the $^3P_0$ model vertex factor. Our results for the decay amplitudes are compared with the existing experimental data and previous $^3P_0$ and elementary meson emission model calculations. In this respect, we show that distinct quark models differ in the number of missing resonances they predict and also in the quantum numbers of states. Therefore, future experimental results will be important in order to disentangle different models of baryon structure. Finally, in the appendices, we provide some details of our calculations, including the derivation of all relevant flavor couplings with strangeness-suppression. This derivation may be helpful to calculate the open-flavor decay amplitudes starting from other models of baryons.

hep-ph↗

arXiv2016

Open flavor strong decays

In this contribution, we discuss the results of a QM calculation of the open-flavor strong decays of **** light nucleon resonances. These are the results of a recent calculation, where we used a modified $^3P_0$ model for the amplitudes and the U(7) algebraic model and the Hypercentral Quark Model to predict the baryon spectrum. The decay amplitudes are compared with the existing experimental data.

hep-ph↗

arXiv2014

Quark structure of the $X(3872)$ and $χ_b(3P)$ resonances

We discuss the nature of the $χ_b(3P)$ and $X(3872)$ mesons: Are the $χ_b(3P)$'s standard $b \bar b$ mesons or $b \bar b$ states with a significative continuum component? Is the $X(3872)$ a $c \bar c$ state with continuum coupling effects or a meson-meson molecule? To do that, we compare quark model and unquenched quark model results for the mass barycenter and splittings of the $χ_b(3P)$ multiplet. Future and more precise experimental results will discriminate between the two interpretations. In the case of the $X(3872)$, we interpret it a $c \bar c$ core plus higher Fock components due to the coupling to the meson-meson continuum, thus we think that it is compatible with the meson $χ_{c1}(2P)$, with $J^{PC} = 1^{++}$. The $J^{PC} = 1^{++}$ quantum numbers are in agreement with the experimental results found by the LHCb collaboration. In our view, the $X(3872)$'s mass is lower than the quark model's predictions because of self energy shifts. We also provide an estimation of the open charm/bottom strong decay modes of the $X(3872)$ and $χ_b(3P)$ mesons, such as $X(3872) \rightarrow D \bar D^*$ and $χ_{b2}(3P) \rightarrow B \bar B$, and radiative transitions.

nucl-th↗

arXiv2013

Interpretation of the X(3872) as a charmonium state plus an extra component due to the coupling to the meson-meson continuum

We present a quark model calculation of the charmonium spectrum with self energy corrections due to the coupling to the meson-meson continuum. The bare masses used in the calculation are computed within the relativized quark model by Godfrey and Isgur. The strong decay widths of 3S, 2P, 1D and 2D $c \bar c$ states are also calculated, in order to set the values of the $^3P_0$ pair-creation model's parameters we use to compute the vertex functions of the loop integrals. Finally, the nature of the X(3872) resonance is analyzed and the main possibilities ($c \bar c$ state or $D \bar D^*$ molecule) are discussed. According to our results, the X(3872) is compatible with the meson $χ_{c1}(2P)$, with $J^{PC} = 1^{++}$, and is thus interpreted as a $c \bar c$ core plus higher Fock components due to the coupling to the meson-meson continuum. These $J^{PC} = 1^{++}$ quantum numbers are in agreement with the experimental results found by the LHCb collaboration. In our view, the X(3872)'s mass is lower than the quark model's predictions because of self energy shifts.

hep-ph↗