Document Type
Article
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
= 0.0035 √ 0.0024stat √ 0.0029sys. The systematic uncertainty studies are described in detail, which can serve as a guide for future applications of tau polarimetry. A proposed e− beam longitudinal polarization upgrade to the SuperKEKB e+e− collider would benefit from this technique.
Digital Object Identifier (DOI)
Publication Info
Published in Physical Review D, Volume 108, Issue 9, 2023.
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Rights
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
APA Citation
Lees, J. P., Poireau, V., Tisserand, V., Grauges, E., Palano, A., Eigen, G., Brown, D. N., Kolomensky, Yu. G., Fritsch, M., Koch, H., Cheaib, R., Hearty, C., Mattison, T. S., McKenna, J. A., So, R. Y., Blinov, V. E., Buzykaev, A. R., Druzhinin, V. P., Kozyrev, E. A., … Wu, S. L. (2023a). Precision .Physical Review D, 108(9). https://doi.org/10.1103/physrevd.108.092001