Structures of the f0(980)f_0(980), a0(980)a_0(980) mesons and the strong coupling constants gf0K+K−g_{f_0 K^+ K^-}, ga0K+K−g_{a_0 K^+ K^-} with the light-cone QCD sum rules

In this article, with the assumption of explicit isospin violation arising from the $f_0(980)-a_0(980)$ mixing, we take the point of view that the scalar mesons $f_0(980)$ and $a_0(980)$ have both strange and non-strange quark-antiquark components and evaluate the strong coupling constants $g_{f_0 K^+ K^-}$ and $g_{a_0 K^+ K^-}$ within the framework of the light-cone QCD sum rules approach. The large strong scalar-$KK$ couplings through both the $n\bar{n}$ and $s\bar{s}$ components $g^{\bar{n}n}_{f_0 K^+ K^-}$, $g^{\bar{s}s}_{f_0 K^+ K^-}$, $g^{\bar{n}n}_{a_0 K^+ K^-}$ and $g^{\bar{s}s}_{a_0 K^+ K^-}$will support the hadronic dressing mechanism, furthermore, in spite of the constituent structure differences between the $f_0(980)$ and $a_0(980)$ mesons, the strange components have larger strong coupling constants with the $K^+K^-$ state than the corresponding non-strange ones, $g_{f_0 K^+ K^-}^{\bar{s}s}\approx \sqrt{2}g_{f_0 K^+ K^-}^{\bar{n}n}$ and $g_{a_0 K^+ K^-}^{\bar{s}s}\approx \sqrt{2} g_{a_0 K^+ K^-}^{\bar{n}n}$. From the existing controversial values, we can not reach a general consensus on the strong coupling constants $g_{f_0 K^+ K^-}$, $g_{a_0 K^+ K^-}$ and the mixing angles.Comment: 14 pages; Revised versio

On the velocity of moving relativistic unstable quantum systems

We study properties of moving relativistic quantum unstable systems. We show that in contrast to the properties of classical particles and quantum stable objects the velocity of moving freely relativistic quantum unstable systems can not be constant in time. We show that this new quantum effect results from the fundamental principles of the quantum theory and physics: It is a consequence of the principle of conservation of energy and of the fact that the mass of the quantum unstable system is not defined. This effect can affect the form of the decay law of moving relativistic quantum unstable systems.Comment: LaTeX2e, 11 pages, new coments and references adde