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Paper   IPM / P / 15090
School of Physics
  Title:   The new a1(1420) state: structure, mass and width
1.  H. Sundu
2.  S.S. Agaev
3.  K. Azizi
  Status:   Published
  Journal: Phys. Rev. D
  Vol.:  97
  Year:  2018
  Pages:   054001
  Supported by:  IPM
The structure, spectroscopic parameters and width of the resonance with quantum numbers JPC=1++ discovered by the COMPASS Collaboration and classified as the a1(1420) meson are examined in the context of QCD sum rule method. In the calculations the axial-vector meson a1(1420) is treated as a four-quark state with the diquark-antidiquark structure. The mass and current coupling of a1(1420) are evaluated using QCD two-point sum rule approach. Its observed decay mode a1(1420) → f0(980)π, and kinematically allowed ones, namely a1K∗±K±, a1K∗0 K0 and a1K∗0 K0 channels are studied employing QCD sum rules on the light-cone. Our prediction for the mass of the a1(1420) state ma1=1416−79+81 MeV is in excellent agreement with the experimental result. Width of this state Γ = 145.52 ±20.79 MeV within theoretical and experimental errors is also in accord with the COMPASS data.

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