Precision e beam polarimetry at an e+e B factory using tau-pair events

BABAR Collaboration

Research output: Contribution to journalArticlepeer-review


We present a new technique, "tau polarimetry,"for measuring the longitudinal beam polarization present in an e+e- collider through the analysis of e+e-→τ+τ- events. By exploiting the sensitivity of τ decay kinematics to the longitudinal polarization of the beams, we demonstrate that the longitudinal polarization can be measured with a 3 per mil systematic uncertainty at the interaction point using a technique that is independent of spin and beam transport modeling. Using 424.2±1.8 fb-1 of BABAR data at s=10.58 GeV, the average longitudinal polarization of the PEP-II e+e- collider has been measured to be ⟨P.

Original languageEnglish (US)
Article number092001
JournalPhysical Review D
Issue number9
StatePublished - Nov 1 2023

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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