On Partial Compositeness and the CP asymmetry in charm decays

TL;DR

This paper explores whether new physics from Partial Compositeness, especially within Composite Higgs and Supersymmetric models, can explain the large CP asymmetry observed in charm decays, while satisfying flavor constraints.

Contribution

It demonstrates that Composite Higgs models at around 10 TeV can explain the CP asymmetry, and that supersymmetric realizations can better address lepton sector constraints and collider signatures.

Findings

Composite Higgs models can account for the CP asymmetry at ~10 TeV scale.

Supersymmetric models with superpartners near TeV scale can saturate the CP asymmetry.

Neutron EDM is predicted to be near current experimental sensitivity.

Abstract

Recently, the LHCb and CDF collaborations reported the measure of an unexpectedly large direct CP asymmetry in D meson decays. In this paper we ask if new physics associated with Partial Compositeness could plausibly explain this result. We find that Composite Higgs models with mass scale around 10 TeV can account for it, while marginally satisfying all other flavor constraints in the quark sector. The minimal framework is however inadequate in the lepton sector due to the strong constraint from \mu\ to e \gamma. This tension can be efficiently alleviated by realizing Partial Compositeness within Supersymmetry. The resulting models can saturate the CP asymmetry in D decays for superpartner masses close to the TeV scale and somewhat large A-terms. The supersymmetric realization of Partial Compositeness also offers a predictive and phenomenologically viable organizing principle for R-Parity violation, and may result in very distinctive signatures at hadron colliders. With or without Supersymmetry, the neutron EDM is expected to be around the present experimental sensitivity.