Pole position of the a1(1260 ) from τ -decay
Abstract
We perform an analysis of the three-pion system with quantum numbers JP C=1++ produced in the weak decay of τ leptons. The interaction is known to be dominated by the axial meson a1(1260 ). We build a model based on approximate three-body unitary and fix the free parameters by fitting it to the ALEPH data on τ-→π-π+π-ντ decay. We then perform the analytic continuation of the amplitude to the complex energy plane. The singularity structures related to the π π subchannel resonances are carefully addressed. Finally, we extract the a1(1260 ) pole position mp(a1(1260 ))-i Γp(a1(1260 ))/2 with mp(a1(1260 ))=(1209 ±4-9+12) MeV , Γp(a1(1260 ))=(576 ±1 1-20+89) MeV .
- Publication:
-
Physical Review D
- Pub Date:
- November 2018
- DOI:
- 10.1103/PhysRevD.98.096021
- arXiv:
- arXiv:1810.00016
- Bibcode:
- 2018PhRvD..98i6021M
- Keywords:
-
- High Energy Physics - Phenomenology
- E-Print:
- 20 pages, 22 figures