Tau decay and the structure of the a1
Abstract
Description
We analyse the decay $τ\toπππν$ based on the recently developed techniques to generate axial-vector resonances dynamically. Under the assumption that the a1 is a coupled-channel meson-molecule, the spectral function is described surprisingly well by adjusting only one free parameter. Including, in addition, an elementary a1 corrupts the results.
Replaced figures, due to an error in the calculation, which we corrected. (Conclusions did not change.) Dropped last part discussing higher order effect in favour of further elucidation
Replaced figures, due to an error in the calculation, which we corrected. (Conclusions did not change.) Dropped last part discussing higher order effect in favour of further elucidation