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.
Precision e- beam polarimetry at an e+e- B factory using tau-pair events
Li Y.;Finocchiaro G.;Banerjee S.;Cenci R.;Gaz A.;Marchiori G.;Batignani G.;Lusiani A.Membro del Collaboration Group
;Ferroni F.;
2023
Abstract
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.File in questo prodotto:
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PhysRevD.108.092001.pdf
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