Quantum loops in radiative decays of the $a_1$ and $b_1$ axial-vector mesons

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)$axial-vectormesonsinto$πγ$.Unlikethecaseofthe$a_1$,the$b_1$radiativedecayissystematicallyunderestimatedattreelevel.Inthisworkweevaluateforthefirsttimetheloopcontributioncomingfromaninitial$VP$vertex.Despitethelargesuperficialdivergenceoftheloops,theconvergenceoftherelevantloopscanbeestablishedbyusingargumentsofgaugeinvariance.Thepartialdecaywidthsobtainedagreeverywellwiththeexperimentalvalueswithinuncertainties,andshowthattheloopcontributioniscrucialinthe$b_1$caseandalsoimportantforthe$a_1$ case.

16 pages, 4 figurs Added extra discussion

References in corpus (2)

• Clues for the existence of two $K_1(1270)$ resonances
• Ds0*(2317) and Ds1(2460) mesons in two-body B-meson decays

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• Revising the $f_1(1420)$ resonance
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• The role of the N*(1535) resonance and the pi^- p --> KY amplitudes in the OZI forbidden pi N --> phi N reaction
• On the role of meson loops in the $f_0(1710)$ decay into $V\gamma$
• Theoretical description of the $\mathbf{J}/\mathbf{\psi }\to \mathbf{\eta }({\mathbf{\eta }}^{\prime }){\mathbf{h}}_1(1380)$, $\mathbf{J}/\mathbf{\psi }\to \mathbf{\eta }({\mathbf{\eta }}^{\prime }){\mathbf{h}}_1(1170)$ and $\mathbf{J}/\mathbf{\psi }\to {\mathbf{\pi }}^0{\mathbf{b}}_1(1235{)}^0$ reactions
• Radiative decay into $\gamma P$ of the low lying axial-vector mesons
• The role of $a_1(1260)$ in ${\pi }^{-}p\to a_1^{-}(1260)p$ and ${\pi }^{-}p\to {\pi }^{-}{\rho }^{0}p$ reactions near threshold
• Tau decay into ${\nu }_{\tau }$ and $a_1(1260)$, $b_1(1235)$, and two $K_1(1270)$
• The dynamically generated $h_1$ state by the $K^{\ast }{\bar{K}}^{\ast }$ interaction and its $K_1(1270)\bar{K}$ and $b_1(1235)\pi$ decays
• Amplitude Analysis of the Isospin-Violating Decay $J/\psi \to \gamma \eta {\pi }^0$