Measurement of branching fractions, CP asymmetry, and isospin asymmetry for Bργ\boldsymbol{B\rightarrow\rho\gamma} decays using Belle and Belle II data

Collaboration
Jul 12, 2024
12 pages
e-Print:
Report number:
  • Belle II Preprint 2023-019; KEK Preprint 2023-37; UCHEP-24-04,
  • Belle II Preprint 2023-019; KEK Preprint 2023-37
Experiments:

Citations per year

20222023202402
Abstract: (arXiv)
We present measurements of B+ρ+γB^{+}\rightarrow\rho^{+}\gamma and B0ρ0γB^{0}\rightarrow\rho^{0}\gamma decays using a combined data sample of 772×106772 \times 10^6BBB\overline{B} pairs collected by the Belle experiment and 387×106387\times 10^6BBB\overline{B} pairs collected by the Belle II experiment in e+ee^{+}e^{-} collisions at the Υ(4S)\Upsilon (4S) resonance. After an optimized selection, a simultaneous fit to the Belle and Belle II data sets yields 114±12114\pm 12B+ρ+γB^{+}\rightarrow\rho^{+}\gamma and 99±1299\pm 12B0ρ0γB^{0}\rightarrow\rho^{0}\gamma decays. The measured branching fractions are (13.11.91.2+2.0+1.3)×107(13.1^{+2.0 +1.3}_{-1.9 -1.2})\times 10^{-7} and (7.5±1.30.8+1.0)×107(7.5\pm 1.3^{+1.0}_{-0.8})\times 10^{-7} for B+ρ+γB^{+}\rightarrow\rho^{+}\gamma and B0ρ0γB^{0}\rightarrow\rho^{0}\gamma decays, respectively, where the first uncertainty is statistical and the second is systematic. We also measure the isospin asymmetry AI(Bργ)=(10.911.77.3+11.2+7.8)%A_{\rm I}(B\rightarrow\rho\gamma)=(10.9^{+11.2 +7.8}_{-11.7 -7.3})\% and the direct CP asymmetry ACP(B+ρ+γ)=(8.2±15.21.2+1.6)%A_{CP}(B^{+}\rightarrow\rho^{+}\gamma)=(-8.2\pm 15.2^{+1.6}_{-1.2})\%.
Note:
  • 12 pages, 4 figures