Constraints on unparticle interactions from particle and antiparticle oscillations

Abstract

Unparticles have dramatic effects on particle and antiparticle oscillations in meson–antimeson and muonium–antimuonium systems. Unlike the usual tree-level contributions to meson oscillations from heavy-particle exchange, which results in a small Γ ₁₂, the unparticle may have sizeable contributions to both M ₁₂ and Γ ₁₂ due to the fractional dimension $d_{\mathcal{U}}$ of the unparticle. If the unparticle effect dominates the contributions (which may happen in D ⁰– $\bar{D}^{0}$ mixing) to the meson mixing parameters x and y, we find that $x/y=\cot(\pi d_{\mathcal{U}})$ . The mass difference Δm in meson mixing can provide interesting constraints on the unparticle interactions. The unparticle interaction can significantly enhance the CP asymmetry in meson mixing, which can be tested in more accurate experiments in the future. Interesting constraints on unparticle and particle interactions can also be obtained using muonion and antimuonion oscillation data.