What can be learned from tau -> 3 pi nu_tau for the axial form factor of the nucleon

by Dr Sergi Gonzalez-Solis (Indiana University Bloomington)

Wednesday 22 May 2019, 10:00 → 11:00 Asia/Shanghai

North Building 322 (ITP)

Electroweak form factors provide valuable information on the internal structure of the existing composite hadrons, and their understanding is of utmost importance in any theory or model of strong interactions. For the nucleon, the electromagnetic form factors are by far best understood, both theoretically and experimentally, than the axial and the induced pseudoscalar form factors. While the rho(770) and omega(782) vector mesons play an important role in the description of the electromagnetic form factors of the nucleon, the a1(1260) meson presumably dominates the axial-vector current transition. In this talk, we will investigate the axial-vector weak hadronic current by analyzing the 2013 ALEPH experimental data on the tau->3pi nu_tau axialvector spectral function. The latter provides a rather clean benchmark to study the axial-vector form factor since the 3pi system is predominantly in a JPC = 1++ state produced through the a1(1260) axial-vector meson. As a side result, we will discuss what can be learned for the low-Q2 behavior of the axial form factor of the nucleon.

Talk_ITP_May22.pdf