Constraints on Unparticle Physics from Solar and KamLAND Neutrinos

TL;DR

This paper investigates how solar and KamLAND neutrino decay limits constrain unparticle physics, deriving bounds on the energy scale and exploring implications for theories with conformal invariance and many flavors.

Contribution

It provides new bounds on unparticle interaction parameters from neutrino decay data, considering both scalar and vector unparticles within a conformal framework.

Findings

Bounds on the scale mbda in the TeV range for scalar unparticles.

Bounds on the scale mbda in the meV range for vector unparticles.

Comparable bounds to collider production rates for certain parameter regions.

Abstract

Interest has been directed recently towards low energy implications of a non-trivial conformal sector of an effective field theory with an IR fixed point (\Lambda), manifest in terms of ``unparticles'' with bizarre properties. We re-examine the implications of the limits on decay lifetimes of solar neutrinos for unparticle interactions. We study in detail the fundamental parameter space (\Lambda, M) and derive bounds on the energy scale M characterizing the new physics. We work strictly within the framework where conformal invariance holds down to low energies. We first assume that couplings of the unparticle sector to the Higgs field are suppressed and derive bounds with \Lambda in the TeV region from neutrino decay into scalar unparticles. These bounds are significant for values of the anomalous dimension of the unparticle operator 1.0 < d < 1.2. For a region of the parameter space, we show that the bounds are comparable to those arising from production rates at high energy colliders. We then relax our assumption, by considering a more natural framework which does not require a priori restrictions on couplings of Higgs-unparticle operators, and derive bounds with \Lambda in meV region from neutrino decay into vector unparticles. Such low scales for the IR fixed point are relevant in gauge theories with many flavors.