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...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 J_(τ)(τ^(+)τ^(-) atom with J^(PC)=1^(--))atom signal can be observed with a significance larger than 5o 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.展开更多
基金supported by National Key Research and Development Program of China(2020YFA0406300)National Natural Science Foundation of China(11975076,12161141008,12135005,12075018,12005040,and 12335004)the Fundamental Research Funds for the Central Universities(RF1028623046).
文摘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 J_(τ)(τ^(+)τ^(-) atom with J^(PC)=1^(--))atom signal can be observed with a significance larger than 5o 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.
