Up Asymmetries From Exhilarated Composite Flavor Structures

TL;DR

This paper introduces warped extra dimension models that explain observed asymmetries in top quark and D meson decays, predicting distinctive signatures for future collider experiments and providing a new flavor paradigm within partial compositeness.

Contribution

It proposes a novel class of composite Higgs models linking top and charm asymmetries with flavor physics, consistent with current data and testable in upcoming experiments.

Findings

Explains the tar t forward-backward asymmetry via axial resonance exchange.

Predicts larger CP asymmetry in D^0 o K^+K^- compared to D^0 o \pi^+\

Abstract

We present a class of warped extra dimension (composite Higgs) models which conjointly accommodates the t\bar t forward-backward asymmetry observed at the Tevatron and the direct CP asymmetry in singly Cabibbo suppressed D decays first reported by the LHCb collaboration. We argue that both asymmetries, if arising dominantly from new physics beyond the Standard Model, hint for a flavor paradigm within partial compositeness models in which the right-handed quarks of the first two generations are not elementary fields but rather composite objects. We show that this class of models is consistent with current data on flavor and CP violating physics, electroweak precision observables, dijet and top pair resonance searches at hadron colliders. These models have several predictions which will be tested in forthcoming experiments. The CP asymmetry in D decays is induced through an effective operator of the form (\bar u c)_{V+A}(\bar s s)_{V+A} at the charm scale, which implies a larger CP asymmetry in the D^0\to K^+K^- rate relative the D^0\to \pi^+\pi^- channel. This prediction is distinctive from other Standard Model or dipole-based new physics interpretation of the LHCb result. CP violation in D-\bar D mixing as well as an an excess of dijet production of the LHC are also predicted to be observed in a near future. A large top asymmetry originates from the exchange of an axial resonance which dominantly produces left-handed top pairs. As a result a negative contribution to the lepton-based forward-backward asymmetry in t\bar t production, as well as O(10%) forward-backward asymmetry in b\bar b production above m_{b\bar b}\simeq 600GeV at the Tevatron is expected.