2-7 June 2019
Simon Fraser University
America/Vancouver timezone
Welcome to the 2019 CAP Congress Program website! / Bienvenue au siteweb du programme du Congrès de l'ACP 2019 !

76 - Measurement of SuperKEKB Electron Beam Polarization through Tau Forward-Backward Polarization Asymmetry

Jun 4, 2019, 5:19 PM
SWH 9082 + AQ South-East Corner / coin sud-est (Simon Fraser University)

SWH 9082 + AQ South-East Corner / coin sud-est

Simon Fraser University

Poster Competition (Graduate Student) / Compétition affiches (Étudiant(e) 2e ou 3e cycle) Particle Physics / Physique des particules (PPD) PPD Poster Session & Student Poster Competition Finals (26) | Session d'affiches PPD et finales du concours d'affiches étudiantes (26)


Caleb Miller (University of Victoria)


Presently the Belle II experiment at SuperKEKB is colliding $e^+e^-$ beams at the $\Upsilon(4S)$ resonance. These beams currently have no polarization, but if SuperKEKB and Belle II were to be upgraded to make use of polarized electron beams a significant number of electroweak precision measurements could be made. However, in addition to the technical difficulties in creating a polarized beam for collisions, it is difficult to know the exact amount of polarization that remains at the moment of collision. This uncertainty can become a leading systematic uncertainty limiting the precision of physics measurements.
The beam polarization can be measured with sub-percent precision by making use of the relationship between beam polarization and the forward-backward asymmetry in the polarization of tau leptons produced in the $e^+e^-$ collisions. By measuring the asymmetry, a precise value for the beam polarization at the e+e- interaction point can be determined.
In this talk I will show results from applying this analysis method to the unpolarized beams delivered by SLAC to the BaBar experiment. I will also discuss the feasibility of applying the analysis technique as a measurement tool of beam polarization for a potential upgrade of polarized electron beams to SuperKEKB/Belle II.

Primary author

Caleb Miller (University of Victoria)


Michael Roney (University of Victoria)

Presentation materials