In the chiral unitary approach with dimensional regularization and new photon-baryon diagrams, the computed Lambda(1520) to gamma Sigma0 width matches BESIII data while the gamma Lambda width underpredicts the CLAS result.
Quantum loops in radiative decays of the $a_1$ and $b_1$ axial-vector mesons
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abstract
A previous model where the low-lying axial-vector mesons are dynamically generated, implementing unitarity in coupled channels in the vector-pseudoscalar ($VP$) meson interaction, is applied to evaluate the decay widths of the a_1(1260)$ and $b_1(1235)$ axial-vector mesons into $\pi\gamma$. Unlike the case of the $a_1$, the $b_1$ radiative decay is systematically underestimated at tree level. In this work we evaluate for the first time the loop contribution coming from an initial $VP$ vertex. Despite the large superficial divergence of the loops, the convergence of the relevant loops can be established by using arguments of gauge invariance. The partial decay widths obtained agree very well with the experimental values within uncertainties, and show that the loop contribution is crucial in the $b_1$ case and also important for the $a_1$ case.
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Radiative decays of the $\Lambda(1520)$ as a dynamically generated resonance
In the chiral unitary approach with dimensional regularization and new photon-baryon diagrams, the computed Lambda(1520) to gamma Sigma0 width matches BESIII data while the gamma Lambda width underpredicts the CLAS result.