Lepton flavor violating processes in unparticle physics

TL;DR

This paper investigates how unparticle physics could influence lepton flavor violating processes in meson decays and electron-positron scattering, providing constraints on unparticle couplings and analyzing energy dependence of cross sections.

Contribution

It offers new insights into unparticle effects on lepton flavor violation and explores constraints on unparticle couplings based on current experimental data.

Findings

Scalar unparticle coupling constraints depend on unparticle scaling dimension

Cross section for $e^+e^- o l^-l'^+$ varies with energy and unparticle dimension

No current constraints on vector unparticle couplings from $B^0$ decay data

Abstract

We study the virtual effects of unparticle physics in the lepton flavor violating processes $M^0\to l^+l'^-$ and $e^+e^-\to l^+l'^-$ scattering, where $M^0$ denotes the pseudoscalar mesons: $\pi^0,K_L, D_0,B_0,B_s^0$ and $l,l'$ denote two different lepton flavors. For the decay of $B^0\to l^+l'^-$, there is no constraint from the current experimental upper bounds on the vector unparticle coupling with leptons. The constraint on the coupling constant between scalar unparticle field and leptons is sensitive to the scaling dimension of the unparticle $d_{\cal U}$. For the scattering process $e^-e^+\to l^-l'^+$, there is only constraint from experiments on the vector unparticle couplings with leptons but no constraint on the scalar unparticle. We study the $\sqrt s$ dependence of the cross section $ \frac{1}{\sigma} \frac{d\sigma}{d\sqrt s}$ of $e^+e^-\to l^-l'^+$ with different values of $d_{\cal U}$. If $d_{\cal U}=1.5$, the cross section is independent on the center mass energy. For $d_{\cal U}>1.5$, the cross section increases with $\sqrt s$.