Decay of Z Boson into Photon and Unparticle

TL;DR

This paper investigates the rare decay of the Z boson into a photon and unparticle, analyzing the process at one-loop level, and uses LEP I data to constrain unparticle properties.

Contribution

It provides a detailed calculation of Z boson decay into photon and unparticle, highlighting the axial-vector and vector couplings involved, and constrains unparticle parameters using experimental data.

Findings

Photon spectrum terminates at the end point, consistent with Yang's theorem.

LEP I data constrains the unparticle sector parameters.

Only specific axial-vector and vector couplings contribute to the decay.

Abstract

We study the decay of the standard model Z boson into unparticle plus a single photon through a one-loop process. As in the anomaly type decay, only the axial-vector part of the Z coupling matching with the vector unparticle and/or the vector part of the Z coupling matching with the axial-vector unparticle can give a nonzero contribution to the decay. We show that the photon spectrum terminates at the end point in accord with Yang's theorem. Existing data on single photon production at LEP I is used to constrain the unparticle sector.