Collider signals in unparticle physics

TL;DR

Phenomenology of the notion of an unparticle U, recently perceived by Georgi, to describe a scale invariant sector with a nontrivial infrared fixed point at a higher energy scale is explored in details.

Abstract

Phenomenology of the notion of an unparticle U, recently perceived by Georgi, to describe a scale invariant sector with a non-trivial infrared fixed point at a higher energy scale is explored in details. Behaving like a collection of d_U (the scale dimension of the unparticle operator O_U) invisible massless particles, this unparticle can be unveiled by measurements of various energy distributions for the processes Z to fermion pair + U and e-e+ to gamma U at e-e+ colliders, as well as mono-jet production at hadron colliders. We also study the propagator effects of the unparticle through the Drell-Yan tree level process and the one-loop muon anomaly.

Figures (4)

• Figure 1: Normalized decay rate of $Z \to q \bar{q} {\cal U}$ versus $x_1 = 2 E_f/M_Z$ for different values of $d_{\cal U}=1+\epsilon,\,1.5,\,2$, and 3 with $\epsilon$ a small number.
• Figure 2: Normalized monophoton energy spectrum of $e^- e^+ \to \gamma {\cal U}$ for $d_{\cal U}=1+\epsilon,\,1.2,\,1.5,\,2$ and 3 at $\sqrt{s} = 200$ GeV. We have imposed $|\cos\theta_\gamma|<0.95$.
• Figure 3: Fractional difference from the SM prediction of the Drell-Yan invariant mass spectrum for various $d_{\cal U}$ at the Tevatron in units of $\lambda_1^2$. We have chosen $\Lambda_{\cal U} = 1$ TeV. Note that the scales in $\pm y$-axis are different. The curve for $d_{\cal U}=1.5$ is too close to zero for visibility in the current scale.
• Figure 4: Contribution to the muon anomalous magnetic moment from the unparticle versus $d_{\cal U}$ with $\Lambda_{\cal U} = 1$ TeV and the coupling $\lambda_1 = 1,10^{-1},10^{-2}$ and $10^{-3}$.