Broken scale invariant unparticle physics and its prospective effects on the MuonE experiment

Abstract

We investigate the effects of broken scale invariant unparticle at the MUonE experiment. The choice of the broken model is because the original scale-invariant model is severely suppressed by constraints from cosmology and low-energy experiments. Broken scale invariant unparticle model is categorized into four types: pseudoscalar, scalar, axial-vector, and vector unparticle. Each uparticle type is characterized by three free parameters: coupling constant $\lambda$, scaling dimension $d$, and energy scale $\mu$ at which the scale-invariance is broken. After considering all of the available constraints on the model, we find that the MUonE experiment is sensitive to (axial-)vector unparticle with $1 < d < 1.4$ and $1\le \mu \le 12$ GeV.