학술논문
A Measurement of the Branching Ratio of $\pi^0$ Dalitz Decay using $K_L \rightarrow \pi^0\pi^0\pi^0$ Decays
Document Type
Working Paper
Author
Abouzaid, E.; Arenton, M.; Barker, A. R.; Bellantoni, L.; Blucher, E.; Bock, G. J.; Cheu, E.; Coleman, R.; Corcoran, M. D.; Cox, B.; Erwin, A. R.; Escobar, C. O.; Glazov, A.; Golossanov, A.; Gomes, R. A.; Gouffon, P.; Hsiung, Y. B.; Jensen, D. A.; Kessler, R.; Kotera, K.; Ledovskoy, A.; McBride, P. L.; Monnier, E.; Nguyen, H.; Niclasen, R.; Phillips II, D. G.; Ramberg, E. J.; Ray, R. E.; Ronquest, M.; Santos, E.; Slater, W.; Smith, D.; Solomey, N.; Swallow, E. C.; Toale, P. A.; Tschirhart, R.; Wah, Y. W.; Wang, J.; White, H. B.; Whitmore, J.; Wilking, M. J.; Winstein, B.; Winston, R.; Worcester, E. T.; Yamanaka, T.; Zimmerman, E. D.; Zukanovich, R. F.
Source
Phys. Rev. D 100, 032003 (2019)
Subject
Language
Abstract
We present a measurement of $B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma)$, the Dalitz branching ratio, using data taken in 1999 by the E832 KTeV experiment at Fermi National Accelerator Laboratory. We use neutral pions from fully reconstructed $K_L$ decays in flight; the measurement is based on about 60 thousand $K_L \rightarrow \pi^0\pi^0\pi^0 \rightarrow \gamma\gamma~\gamma\gamma~e^+e^-\gamma$ decays. We normalize to $K_L \rightarrow \pi^0\pi^0\pi^0 \rightarrow 6\gamma$ decays. We find $B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma)$ $(m_{e^+e^-}$ > 15 MeV/$c^2)$ = $[3.920 \pm 0.016(stat) \pm 0.036 (syst)] \times 10^{-3}$. Using the Mikaelian and Smith prediction for the $e^+e^-$ mass spectrum, we correct the result to the full $e^+e^-$ mass range. The corrected result is $B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma) = [1.1559 \pm 0.0047(stat) \pm 0.0106 (syst)]$%. This result is consistent with previous measurements and the uncertainty is a factor of three smaller than any previous measurement.
Comment: 11 pages, 7 figures; v2 accepted version
Comment: 11 pages, 7 figures; v2 accepted version