Observation of the bottomonium ground state in the decay
Collaboration
8 pages
Published in:
- Phys.Rev.Lett. 101 (2008) 071801,
- Phys.Rev.Lett. 102 (2009) 029901 (erratum)
e-Print:
- 0807.1086 [hep-ex]
DOI:
Report number:
- BABAR-PUB-08-029,
- SLAC-PUB-13288
Experiments:
View in:
Citations per year
Abstract: (arXiv)
We report the results of a search for the bottomonium ground state eta_b(1S) in the photon energy spectrum with a sample of (109 +/- 1) million of Upsilon(3S) recorded at the Upsilon(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. We observe a peak in the photon energy spectrum at E_gamma = 921.2 {+2.1} {-2.8} (stat) +/- 2.4(syst) MeV with a significance of 10 standard deviations. We interpret the observed peak as being due to monochromatic photons from the radiative transition Upsilon(3S) -> gamma eta_b(1S). This photon energy corresponds to an eta_b(1S) mass of $9388.9 {+3.1} {-2.3} (stat) +/- 2.7(syst) MeV/c2. The hyperfine Upsilon(1S)-eta_b(1S) mass splitting is 71.4 {+2.3} {-3.1} (stat) +/- 2.7(syst) MeV/c2. The branching fraction for this radiative Upsilon(3S) decay is estimated to be (4.8 +/- 0.5(stat) +/- 1.2 (syst)) x 10^(-4).Note:
- 7 pages, 4 postscript figures, submitted to PRL
- 14.40.Gx
- 13.20.Gd
- 14.65.Fy
- electron positron: annihilation
- Upsilon(10355): electroproduction
- Upsilon(10355): radiative decay
- Upsilon(10355): branching ratio
- photon: energy spectrum
- eta/b: mass
- mass difference: (Upsilon(9460) eta/b)
References(20)
Figures(4)