Evidence for the eta_b(1S) in the Decay Upsilon(2S)-> gamma eta_b(1S)

Journal Article · Mon Dec 14 04:00:00 EST 2009 · Phys.Rev.Lett.103:161801,2009

OSTI ID:953022

Aubert, B; Bona, M; Karyotakis, Y; Lees, J P; Poireau, V; Prencipe, E; Prudent, X; Tisserand, V; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Pappagallo, M; Eigen, G; Stugu, B; Sun, L; Battaglia, M; Brown, D N; Kerth, L T; Kolomensky, Yu G ; Lynch, G

We have performed a search for the {eta}{sub 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{sub {gamma}} = 610.5{sub -4.3}{sup +4.5}(stat) {+-} 1.8(syst) MeV, corresponding to an {eta}{sub b}(1S) mass of 9392.9{sub -4.8}{sup +4.6}(stat) {+-} 1.9(syst) MeV/c{sup 2}. The branching fraction for the decay {Upsilon}(2S) {yields} {gamma}{eta}{sub b}(1S) is determined to be (4.2{sub -1.0}{sup +1.1}(stat) {+-} 0.9(syst)) x 10{sup -4}. The ratio {Beta}({Upsilon}(2S) {yields} {gamma}{eta}{sub b}(1S))/{Beta}({Upsilon}(3S) {yields} {gamma}{eta}{sub b}(1S)) = 0.89{sub -0.23}{sup +0.25}(stat){sub -0.16}{sup +0.12}(syst) is consistent with the ratio expected for magnetic dipole transitions to the {eta}{sub b}(1S) meson.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 953022
• Report Number(s): SLAC-PUB-13486; arXiv:0903.1124
• Journal Information: Phys.Rev.Lett.103:161801,2009, Journal Name: Phys.Rev.Lett.103:161801,2009; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
DECAY
Experiment-HEP
HEPEX
FERMILAB ACCELERATOR
M1-TRANSITIONS
MESONS
PHOTONS
RADIATIVE DECAY
RESONANCE
STANFORD LINEAR ACCELERATOR CENTER