Resonant structures in B0 -K+ decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3fb-1 collected with the LHCb detector. The data cannot be described with K+Ï€- resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)- φπ- component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)- amplitude with the Ïâ€Ï€- 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+. © 2014 CERN, for the LHCb Collaboration.
Observation of the resonant character of the Z (4430)-state
PALANO, Antimo;PAPPAGALLO, MARCO IGNAZIO;
2014-01-01
Abstract
Resonant structures in B0 -K+ decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3fb-1 collected with the LHCb detector. The data cannot be described with K+Ï€- resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)- φπ- component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)- amplitude with the Ïâ€Ï€- 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+. © 2014 CERN, for the LHCb Collaboration.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.