Observation of a near-threshold enhancement in the ΛΛ mass spectrum from e+ e− → ΛΛ at √s from 3.51 to 4.60 GeV

The process e+ e− → ϕ ΛΛ 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,...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. D 2021-09, Vol.104 (5), p.1
Main Author: Ablikim, M
Format: Article
Language:English
Subjects:
Exponential functions
Helicity
Quantum numbers
Statistical methods
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The process e+ e− → ϕ ΛΛ 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.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.104.052006