Analysis of the strong coupling constant and the decay width of with QCD sum rules

Guo-Liang Yu; Zhen-Yu Li; Zhi-Gang Wang

doi:10.1140/epjc/s10052-015-3460-3

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2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2015) 75: 243
https://doi.org/10.1140/epjc/s10052-015-3460-3

Regular Article - Theoretical Physics

Analysis of the strong coupling constant $G_{D_{s}^{}D_{s}\phi }$ and the decay width of $D_{s}^{}\rightarrow D_{s}\gamma$ with QCD sum rules

Guo-Liang Yu¹^*, Zhen-Yu Li² and Zhi-Gang Wang¹

¹ Department of Mathematics and Physics, North China Electric Power University, Baoding, 071003, People’s Republic of China
² School of Physics and Electronic Science, Guizhou Normal College, Guiyang, 550018, People’s Republic of China

^* e-mail: yuguoliang2011@163.com

Received: 9 March 2015
Accepted: 14 May 2015
Published online: 3 June 2015

Abstract

In this article, we calculate the form factors and the coupling constant of the vertex $D_{s}^{*}D_{s}\phi$ using the three-point QCD sum rules. We consider the contributions of the vacuum condensates up to dimension 7 in the operator product expansion. And all possible off-shell cases are considered, $\phi$ , $D_{s}$ and $D_{s}^{*}$ , resulting in three different form factors. Then we fit the form factors into analytical functions and extrapolate them into time-like regions, which giving the coupling constant for the process. Our analysis indicates that the coupling constant for this vertex is $G_{D_{s}^{*}D{_{s}}\phi }=4.12\pm 0.70\,\mathrm{GeV}^{-1}$ . The results of this work are very useful in the other phenomenological analysis. As an application, we calculate the coupling constant for the decay channel $D_{s}^{*}\rightarrow D_{s}\gamma$ and analyze the width of this decay with the assumption of the vector meson dominance of the intermediate $\phi (1020)$ . Our final result about the decay width of this decay channel is $\Gamma =0.59\pm 0.15\,\mathrm{keV}$ .