Abstract
QED atoms are composed of unstructured and point-like lepton pairs bound together by the electromag-netic force.The smallest and heaviest QED atom is formed by a τ+τ-pair.Currently,the only known atoms of this type are the e+e-and μ+e-atoms,which were discovered 64 years ago and remain the sole examples found thus far.We demonstrate that the Jτ(τ+τ-atom with JPC=1--)atom signal can be observed with a significance larger than 5σ including both statistical and systematic uncertainties,via.the process e+e-→X+Y-(E)(X,Y=e,μ,π,K,or ρ,and(E) is the missing energy due to unobserved neutri-nos)with 1.5 ab-1 data taken around the τ pair production threshold.The τ lepton mass can be measured with a precision of 1 keV with the same data sample.This is within one year's running time of the pro-posed super tau-charm facility in China or super charm-tau factory in Russia.
基金项目
国家重点研发计划(2020YFA0406300)
国家自然科学基金(11975076)
国家自然科学基金(12161141008)
国家自然科学基金(12135005)
国家自然科学基金(12075018)
国家自然科学基金(12005040)
国家自然科学基金(12335004)
中央高校基本科研业务费专项(RF1028623046)
NETL
NSTL
万方数据