Unparticle effects in supernovae cooling

Recently H. Georgi suggested that a scale-invariant unparticle $\mathcal{U}$ sector with an infrared fixed point at high energy can couple with the standard model matter via a higher-dimensional operator suppressed by a high cutoff scale. Intense phenomenological search of this unparticle sector in the collider and flavor physics context has already been made. Here we explore its impact in cosmology, particularly its possible role in the supernovae cooling. We found that the energy-loss rate (and thus the cooling) is strongly dependent on the effective scale ${\Lambda }_{\mathcal{U}}$ and the anomalous dimension $d_{\mathcal{U}}$ of this unparticle theory.

Figure 1

In Fig. 1a, the supernovae energy-loss rate $dϵ/dt$ ($\mathrm{erg}{\mathrm{g}}^{-1}{\mathrm{s}}^{-1}$) as a function of ${\Lambda }_{\mathcal{U}}$ is shown. For the extreme right curve $d_{\mathcal{U}}=1.1$, whereas going to left from right $d_{\mathcal{U}}$ increases by 0.2. The extreme left curve corresponds to $d_{\mathcal{U}}=1.9$. In Fig. 1b, the lower bound on ${\Lambda }_{\mathcal{U}}$ as a function of $d_{\mathcal{U}}$ is shown which follows from the constraint $dϵ/dt<{10}^{19}\mathrm{erg}{\mathrm{g}}^{-1}{\mathrm{s}}^{-1}$. The two horizontal curves in Fig. 1b correspond to ${\Lambda }_{\mathcal{U}}=1\mathrm{TeV}$ and 10 TeV.