TY - JOUR
T1 - Study of hadronic transitions between Y states and observation of $Y(4S) \to \eta Y(1S)$ decay
AU - Lafferty, George
AU - Alwyn, Kim
AU - Bailey, David
AU - Barlow, Roger
AU - Chia, Yaw
AU - Edgar, Christina
AU - West, Timothy
AU - Yi, Jong
AU - The BaBar Collaboration
PY - 2008
Y1 - 2008
N2 - We present a study of hadronic transitions between Υ(mS) (m=4, 3, 2) and Υ(nS) (n=2, 1) resonances based on 347.5 fb−1 of data taken with the BABAR detector at the PEP-II storage rings. We report the first observation of Υ(4S)→ηΥ(1S) decay with a branching fraction B(Υ(4S)→ηΥ(1S))=(1.96±0.06stat±0.09syst)×10−4 and measure the ratio of partial widths Γ(Υ(4S)→ηΥ(1S))/Γ(Υ(4S)→π+π−Υ(1S))=2.41±0.40stat±0.12syst. We set 90% CL upper limits on the ratios Γ(Υ(2S)→ηΥ(1S))/Γ(Υ(2S)→π+π−Υ(1S))<5.2×10−3 and Γ(Υ(3S)→ηΥ(1S))/Γ(Υ(3S)→π+π−Υ(1S))<1.9×10−2. We also present new measurements of the ratios Γ(Υ(4S)→π+π−Υ(2S))/Γ(Υ(4S)→π+π−Υ(1S))=1.16±0.16stat±0.14syst and Γ(Υ(3S)→π+π−Υ(2S))/Γ(Υ(3S)→π+π−Υ(1S))=0.577±0.026stat±0.060syst.
AB - We present a study of hadronic transitions between Υ(mS) (m=4, 3, 2) and Υ(nS) (n=2, 1) resonances based on 347.5 fb−1 of data taken with the BABAR detector at the PEP-II storage rings. We report the first observation of Υ(4S)→ηΥ(1S) decay with a branching fraction B(Υ(4S)→ηΥ(1S))=(1.96±0.06stat±0.09syst)×10−4 and measure the ratio of partial widths Γ(Υ(4S)→ηΥ(1S))/Γ(Υ(4S)→π+π−Υ(1S))=2.41±0.40stat±0.12syst. We set 90% CL upper limits on the ratios Γ(Υ(2S)→ηΥ(1S))/Γ(Υ(2S)→π+π−Υ(1S))<5.2×10−3 and Γ(Υ(3S)→ηΥ(1S))/Γ(Υ(3S)→π+π−Υ(1S))<1.9×10−2. We also present new measurements of the ratios Γ(Υ(4S)→π+π−Υ(2S))/Γ(Υ(4S)→π+π−Υ(1S))=1.16±0.16stat±0.14syst and Γ(Υ(3S)→π+π−Υ(2S))/Γ(Υ(3S)→π+π−Υ(1S))=0.577±0.026stat±0.060syst.
U2 - 10.1103/PhysRevD.78.112002
DO - 10.1103/PhysRevD.78.112002
M3 - Article
SN - 1550-7998
VL - 78
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
IS - 11
M1 - 112002
ER -