What can be learned from the Belle spectrum for the decay τ−→ντKSπ−τ−→ντKSπ−

A theoretical description of the differential decay spectrum for the decay τ−→ντKSπ−τ−→ντKSπ−, which is based on the contributing Kπ   vector and scalar form factors F+Kπ(s) and F0Kπ(s) being calculated in the framework of resonance chiral theory (Rχ  T), additionally imposing constraints from dispersion relations as well as short distance QCD, provides a good representation of a recent measurement of the spectrum by the Belle Collaboration. Our fit allows to deduce the total branching fraction B[τ−→ντKSπ−]=0.427±0.024%B[τ−→ντKSπ−]=0.427±0.024% by integrating the spectrum, as well as the K∗K∗ resonance parameters MK∗=895.3±0.2 MeVMK∗=895.3±0.2 MeV and ΓK∗=47.5±0.4 MeVΓK∗=47.5±0.4 MeV, where the last two errors are statistical only. From our fits, we confirm that the scalar form factor F0Kπ(s) is required to provide a good description, but we were unable to further constrain this contribution. Finally, from our results for the vector form factor F+Kπ(s), we update the corresponding slope and curvature parameters λ+′=(25.2±0.3)×10−3 and λ+″=(12.9±0.3)×10−4, respectively.