Measurements of the mass and width of the ηc using the decay ψ(3686)&rarrηc

Ablikim M; Achasov M N; Alberto D; Ambrose D J; An F F; An Q; An Z H; Bai J Z; Ferroli R B; Ban Y; Becker J; Berger N; Bertani M B; Bian J M; Boger E; Bondarenko O; Boyko I; Briere R A; Bytev V; Cai X; Calcaterra A C; Cao G F; Chang J F; Chelkov G; Chen G; Chen H S; Chen H X; Chen J C; Chen M L; Chen S J; Chen Y; Chen Y B; Cheng H P; Chu Y P; Cronin Hennessy D; Dai H L; Dai J P; Dedovich D; Deng Z Y; Denysenko I

Engineering Village

华中师范大学; 清华大学; 山西大学; 郑州大学; 杭州师范大学; indiana university; Indiana university; 注册单位单

摘要

The mass and width of the lowest-lying S-wave spin singlet charmonium state, the ηc, are measured using a data sample of 1.06×108 ψ(3686) decays collected with the BESIII detector at the BEPCII storage ring. We use a model that incorporates full interference between the signal reaction, ψ(3686)&rarrγηc, and a nonresonant radiative background to describe the line shape of the ηc successfully. We measure the ηc mass to be 2984.3±0.6±0.6MeV/c2 and the total width to be 32.0±1.2±1.0MeV, where the first errors are statistical and the second are systematic.

关键词

Charmonium Data sample Line shape Nonresonant Spin singlets