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Journal Articles Physical Review Letters Year : 2014

Observation of the resonant character of the $Z(4430)^-$ state

R. Aaij
  • Function : Author
J. He
J. Cogan
O. Leroy
J. Serrano


Resonant structures in $B^0\to\psi'\pi^-K^+$ decays are analyzed by performing a four-dimensional fit of the decay amplitude, using $pp$ collision data corresponding to $\rm 3 fb^{-1}$ collected with the LHCb detector. The data cannot be described with $K^+\pi^-$ resonances alone, which is confirmed with a model-independent approach. A highly significant $Z(4430)^-\to\psi'\pi^-$ component is required, thus confirming the existence of this state. The observed evolution of the $Z(4430)^-$ amplitude with the $\psi'\pi^-$ mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin-parity is determined unambiguously to be $1^+$.

Dates and versions

in2p3-00975399 , version 1 (08-04-2014)



R. Aaij, Y. Amhis, S. Barsuk, O. Callot, J. He, et al.. Observation of the resonant character of the $Z(4430)^-$ state. Physical Review Letters, 2014, 112, pp.222002. ⟨10.1103/PhysRevLett.112.222002⟩. ⟨in2p3-00975399⟩
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