Evidence for the eta(b)(1S) Meson in Radiative Upsilon(2S) Decay
Collaboration
7 pages
Published in:
- Phys.Rev.Lett. 103 (2009) 161801
e-Print:
- 0903.1124 [hep-ex]
Report number:
- SLAC-PUB-13486,
- BABAR-PUB-08-052
Experiments:
View in:
Citations per year
Abstract: (arXiv)
We have performed a search for the eta_b(1S) meson in the radiative decay of the Upsilon(2S) resonance using a sample of 91.6 million Upsilon(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E_gamma = 610.5 {+4.5} {-4.3} (stat) +/- 1.8 (syst) MeV, corresponding to an eta_b(1S) mass of 9392.9 {+4.6} {-4.8} (stat) +/- 1.9 (syst) MeV/c^2. The branching fraction for the decay Upsilon(2S) --> gamma eta_b(1S) is determined to be (4.2 {+1.1} {-1.0} (stat) +/- 0.9 (syst)) x 10^(-4). The ratio B(Upsilon(2S) --> gamma eta_b(1S))/B(Upsilon(3S) --> gamma eta_b(1S)) = 0.89 {+0.25} {-0.23} (stat) {+0.12}{-0.16} (syst) is consistent with the ratio expected for magnetic dipole transitions to the eta_b(1S) meson.Note:
- 7 pages, 2 postscript figures, submitted to Phys. Rev. Lett
- 14.40.Gx
- 13.20.Gd
- 14.65.Fy
- electron positron: annihilation
- photon: energy spectrum
- transition: magnetic
- Upsilon(10020): radiative decay
- Upsilon(10020): branching ratio
- eta/b: mass
- BaBar
References(19)
Figures(2)