Flavors and Phases in Unparticle Physics

TL;DR

This paper explores how unparticle physics can induce flavor-changing neutral currents in the Standard Model, revealing potential observable effects like CP asymmetries in meson decays.

Contribution

It introduces a framework connecting SM flavor structures to unparticles via a high-energy $ ext{Z}_ ext{B}$ charge scheme, analyzing resulting FCNC effects and CP violation.

Findings

FCNC effects relate to fermion mass ratios.

No new CP-violating phases beyond CKM.

Potential 10% direct CP asymmetries in meson decays.

Abstract

Inspired by the recent Georgi's unparticle proposal, we study the flavor structures of the standard model (SM) particles when they couple to unparticles. At a very high energy scale, we introduce $\BZ$ charges for the SM particles, which are universal for each generation and allow $\BZ$ fields to distinguish flavor generations. At the $\Lambda_{\UP}$ scale, $\BZ$ operators and charges are matched onto unparticle operators and charges, respectively. In this scenario, we find that tree flavor changing neutral currents (FCNCs) can be induced by the rediagonalizations of the SM fermions. As an illustration, we employ the Fritzsch ansatz to the SM fermion mass matrices and we find that the FCNC effects could be simplified to be associated with the mass ratios denoted by $\sqrt{m_{i}m_{j}/m^2_{3}}$, where $m_3$ is the mass of the heaviest particle in each type of fermion generations and $i, j$ are the flavor indices. In addition, we show that there is no new CP violating phase beside the unique one in the CKM matrix. We use $\bar B_{q}\to \ell^{+} \ell^{-}$ as examples to display the new FCNC effects. In particular, we demonstrate that the direct CP asymmetries in the decays can be $O(10%)$ due to the peculiar CP conserving phase in the unparticle propagator.