Observation of a near-threshold enhancement in the Λ Λ ¯ mass spectrum from e+e- →φ Λ Λ ¯ at s from 3.51 to 4.60 GeV

The BESIII Collaboration

Результат исследования: Научные публикации в периодических изданияхстатьярецензирование

Аннотация

The process e+e-→φΛΛ¯ is studied using data samples collected with the BESIII detector at the BEPCII Collider at center of mass energies s ranging from 3.51 GeV to 4.60 GeV. An enhancement is observed near the threshold of ΛΛ¯. The lineshape of this enhancement is studied in different approaches, including fit with a Breit-Wigner function or a reversed exponential function. The Breit-Wigner function has a mass of (2262±4±28) MeV/c2 and a width of (72±5±43) MeV, where the quoted uncertainties are statistical and systematic, respectively. The rising rate of the reversed exponential function is measured as 33±11±6 MeV/c2. For the ΛΛ¯ system, the JPC quantum numbers of 0-+ and 0++ are rejected, while other JPC hypotheses are possible, according to the helicity-angle study. The energy-dependent cross section of the e+e-→φΛΛ¯ process is measured for the first time in this energy region, and contributions from excited ψ states and vector charmoniumlike Y-states are investigated.

Язык оригиналаанглийский
Номер статьи052006
ЖурналPhysical Review D
Том104
Номер выпуска5
DOI
СостояниеОпубликовано - 1 сен 2021

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