Person:
Mathieu, Vincent

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First Name
Vincent
Last Name
Mathieu
URI
https://hdl.handle.net/20.500.14352/87042
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física Teórica
Area
Física Teórica
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2018 - 20192
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Author: Ketzer, B. × Subject: 51-73 ×

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    Determination of the pole position of the lightest hybrid meson candidate
    (Physical review letters, 2019) Rodas Bilbao, Arkaitz; Pilloni, A.; Albaladejo, M.; Fernández Ramírez, César; Jackura, A.; Mathieu, Vincent; Mikhasenko, M.; Nys, J.; Pauk, V.; Ketzer, B.; Szczepaniak, A. P.
    Mapping states with explicit gluonic degrees of freedom in the light sector is a challenge, and has led to controversies in the past. In particular, the experiments have reported two different hybrid candidates with spin-exotic signature, pi¬_1(1400) and pi_1 (1600), which couple separately to eta pi and eta'pi. This picture is not compatible with recent Lattice QCD estimates for hybrid states, nor with most phenomenological models. We consider the recent partial wave analysis of the eta^(')pi system by the COMPASS Collaboration. We fit the extracted intensities and phases with a coupled-channel amplitude that enforces the unitarity and analyticity of the S matrix. We provide a robust extraction of a single exotic pi_1 resonant pole, with mass and width 1564 +/- 24 +/- 86 and 492 +/- 54 +/- 102 MeV, which couples to both eta^(')pi channels. We find no evidence for a second exotic state. We also provide the resonance parameters of the a_2 (1320) and a_2^' (1700).
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    Pole position of the a_1 (1260) from tau-decay
    (Physical review D, 2018) Mikhasenko, M.; Pilloni, A.; Jackura, A.; Albadalejo, M.; Fernández Ramírez, César; Mathieu, Vincent; Nys, J.; Rodas Bilbao, Arkaitz; Ketzer, B.; Szczepaniak, Adam P.
    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.