${\rm Y}(1s)\to \gamma f_2(1270)$ Decay

Abstract

Decay ${\rm Y}(1s)\to \gamma f_2(1270)$ is studied by an approach in which the tensor meson, $f_2(1270)$, is strongly coupled to gluons. Besides the strong suppression of the amplitude ${\rm Y}(1s)\to \gamma gg,gg\to f_2$ by the mass of b-quark, d-wave dominance in ${\rm Y}(1s)\to \gamma f_2(1270)$ is revealed from this approach, which provides a large enhancement. The combination of these two factors leads to larger $B({\rm Y}(1s)\to \gamma f_2(1270))$. The decay rate of ${\rm Y}(1s)\to \gamma f_2(1270)$ and the ratios of the helicity amplitudes are obtained and they are in agreement with data.

Comments: 8 pages