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Pole position of the a_1 (1260) from tau-decay



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Mikhasenko, M. and Pilloni, A. and Jackura, A. and Albadalejo, M. and Fernández Ramírez, César and Mathieu, V. and Nys, J. and Rodas Bilbao, Arkaitz and Ketzer, B. and Szczepaniak, Adam P. (2018) Pole position of the a_1 (1260) from tau-decay. Physical review D, 98 (9). ISSN 2470-0010

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Official URL: http://dx.doi.org/10.1103/PhysRevD.98.096021


We perform an analysis of the three-pion system with quantum numbers J(PC) = 1(++) thornthorn produced in the weak decay of tau leptons. The interaction is known to be dominated by the axial meson alpha(1) (1260). We build a model based on approximate three-body unitary and fix the free parameters by fitting it to the ALEPH data on tau- -> pi(-)pi(+)pi(-)nu(tau) decay. We then perform the analytic continuation of the amplitude to the complex energy plane. The singularity structures related to the pi pi subchannel resonances are carefully addressed. Finally, we extract the alpha(1) (1260) pole position m(p)((a1(1260)) - i Gamma((a1(1260))(p) /2 with m(p)((a1(1260)) = (1209 +/- 4(-9)(+12)) MeV, Gamma((a1(1260))(p) = (576 +/- 11(-20)(+89)) MeV.

Item Type:Article
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© American Physical Society.
This work was supported by the German Bundesministerium für Bildung und Forschung, the U.S. Department of Energy under Grants No. DE-AC05-06OR23177 and No. DE-FG02-87ER40365, Research Foundation—Flanders (FWO), PAPIIT-DGAPA (UNAM, Mexico) under Grants No. IA101717 and No. IA101819, CONACYT(Mexico)underGrantNo.251817,U.S.National Science Foundation under Grant No. PHY-1415459,Ministerio de Ciencia, Innovación y Universidades (Spain) Grants No. FPA2016-77313-P and No. FPA2016-75654-C2-2-P, and Universidad Complutense de Madrid.

Uncontrolled Keywords:A1; Singularities; Scattering; Unitarity
Subjects:Sciences > Physics > Physics-Mathematical models
Sciences > Physics > Mathematical physics
ID Code:50806
Deposited On:12 Feb 2019 12:41
Last Modified:12 Feb 2019 13:18

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