Search for hb(2P)γχbJ(1P)h_b(2P)\to\gamma\chi_{bJ}(1P) at s=10.860\sqrt{s} = 10.860 GeV

Collaboration
Oct 21, 2024
e-Print:
Report number:
  • Belle Preprint 2024-07; KEK Preprint 2024-19
Experiments:

Citations per year

20222023202401
Abstract: (arXiv)
In the bottomonium sector, the hindered magnetic dipole (M1) transitions between P-wave states hb(2P)χbJ(1P)γh_b(2P) \rightarrow \chi_{bJ}(1P) \gamma, J=0,1,2J=0, \, 1, \, 2, are expected to be severely suppressed according to the Relativized Quark Model, due to the spin flip of the bb quark. Nevertheless, a recent model following the coupled-channel approach predicts the corresponding branching fractions to be enhanced by orders of magnitude. In this Letter, we report the first search for such transitions. We find no significant signals and set upper limits at 90% CL on the corresponding branching fractions: B[hb(2P)γχb0(1P)]<2.7×101\mathcal{B}[h_b(2P)\to\gamma\chi_{b0}(1P)] < 2.7 \times 10^{-1}, B[hb(2P)γχb1(1P)]<5.4×103\mathcal{B}[h_b(2P)\to\gamma\chi_{b1}(1P)] < 5.4 \times 10^{-3} and B[hb(2P)γχb2(1P)]<1.3×102\mathcal{B}[h_b(2P)\to\gamma\chi_{b2}(1P)] < 1.3 \times 10^{-2}. These values help to constrain the parameters of the coupled-channel models. The results are obtained using a 121.4fb1121.4 \, fb^{-1} data sample taken around s=10.860GeV\sqrt{s}= 10.860 \, GeV with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider.