Direct CP violation of $B \to l \nu$ in unparticle physics

TL;DR

This paper explores how unparticle physics can induce observable direct CP violation in B meson decays to leptons, a phenomenon absent in the Standard Model, with potential asymmetries reaching up to 30-100%.

Contribution

It demonstrates that unparticle physics can generate significant direct CP violation in B decays, providing a novel mechanism beyond the Standard Model.

Findings

CP asymmetry can reach 30% for scalar unparticles with tau leptons.

CP asymmetry can reach 100% for vector unparticles with tau leptons.

Constraints limit CP violation to below 8% for scalar and 1% for vector unparticles under universality assumptions.

Abstract

We have investigated the effects of unparticles in decays $B \to l \nu$. It is found that the direct CP violation in the decays, which is zero in SM, can show up due to the CP conserving phase intrinsic in unparticle physics. For $l=\tau$, the direct CP asymmetry can reach 30% for the scalar unparticle contribution, and 100% for the longitudinal vector unparticle contribution under the constraints of ${\rm Br}(B\to\tau\nu)$ and $\nu e$ elastic scattering. If both unparticle-lepton coupling universality and unparticle-quark coupling universality are assumed the constraint from $Br(\pi\to \mu\nu)$ leads that the direct CP violation in $B\to l\nu$ can only reach at most 8% and 1% for scalar and vector unparticle contributions respectively if $d_{\cal U} < 2$. If the direct CP violation is observed in the future it would give strong evidence for the existence of unparticle stuff.