Antisymmetric rank-2 tensor unparticle physics

Abstract

We present the phenomenology of antisymmetric rank-2 tensor unparticle operator ${\mathcal{O}}_{\mathcal{U},\mathcal{A}}^{\ensuremath{\mu}\ensuremath{\nu}}$ with scaling dimension ${d}_{\mathcal{U}}$. We consider the physical effects of operator ${O}_{\mathcal{U},\mathcal{A}}^{\ensuremath{\mu}\ensuremath{\nu}}$ in ${Z}^{0}$ boson invisible decays ${Z}^{0}\ensuremath{\rightarrow}\mathcal{U}$, ${Z}^{0}\ensuremath{\rightarrow}b\overline{b}$ channel, the electroweak precision observable $S$ parameter, and the muon anomalous magnetic dipole moment. The ${Z}^{0}$ boson invisible decay gives a very stringent constraint in the $({\ensuremath{\Lambda}}_{\mathcal{U}},{M}_{\mathcal{U}})$ plane, and only small $r\ensuremath{\equiv}{\ensuremath{\Lambda}}_{\mathcal{U}}/{M}_{\mathcal{U}}\ensuremath{\lesssim}0.1$ is favored, when ${\ensuremath{\Lambda}}_{\mathcal{U}}$ is order of several 100 GeV. When the phenomenological parameter $\ensuremath{\mu}$, which parameterizes the scale invariance breaking, goes to 0, the $S$ parameter and the muon $(g\ensuremath{-}2)$ diverge for $1<{d}_{\mathcal{U}}<2$, while for nonzero $\ensuremath{\mu}$, there will be constraints on $({\ensuremath{\Lambda}}_{\mathcal{U}},{M}_{\mathcal{U}})$ which are more stringent than those obtained from collider experiments.