Observation of a near-threshold enhancement in the $Lambdabar{Lambda}$ mass spectrum from $e^+e^-tophiLambdabar{Lambda}$ at $sqrt{s}$ from 3.51 to 4.60 GeV


الملخص بالإنكليزية

The process $e^+ e^- to phi Lambda bar{Lambda}$ is studied using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies $sqrt{s}$ ranging from $3.51$ to $4.60~{rm GeV}$ . An intermediate resonance structure is observed near the threshold of $Lambda bar{Lambda}$. It has a mass of $(2262 pm 4 pm 28)~{rm{MeV}}/c^{2}$ and a width of $(72 pm 5 pm 43)~rm{MeV}$, where the quoted uncertainties are statistical and systematic, respectively. The $J^{PC}$ quantum numbers of $0^{-+}$ and $0^{++}$ are rejected, while other $J^{PC}$ hypotheses are possible, according to the helicity angle study. The energy-dependent cross section of the $e^+ e^- to phi Lambda bar{Lambda}$ process is measured for the first time in this energy region, and contributions from excited $psi$ states and vector charmonium-like $Y$-states are investigated.

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