Recent topics in CP violation

TL;DR

This paper reviews recent developments in CP violation studies in heavy meson systems, focusing on penguin pollution in B decays and direct CP violation in charm decays, highlighting new bounds and analysis methods.

Contribution

It introduces a new analysis that tightens bounds on penguin contributions in B decays and discusses a method to differentiate Standard Model effects from new physics in charm CP violation.

Findings

Stronger bounds on penguin pollution in B_d to J/psi K decays.

A method to distinguish Standard Model effects from new physics in charm CP violation.

LHCb measurement of large direct CP violation in charm decays.

Abstract

Recent topics regarding CP violation in heavy meson systems are discussed. As an introduction, the status of the Unitarity Triangle fit and CP violation in B meson mixing are briefly reviewed. Two topics are covered in more detail: Penguin pollution in the "golden mode" B_d to J/psi K has gained importance due to the apparent smallness of new physics effects, together with the outstanding precision expected from present and future collider experiments. A very recent analysis is presented, which yields a stronger bound for the maximal influence of penguin contributions than previous analyses and shows the corresponding uncertainty to be reducible with coming data. Direct CP violation in hadronic charm decays received a lot of attention lately, due to a measurement by the LHCb collaboration yielding an unexpectedly large result. While this value is certainly not generically predicted in the Standard Model, it might be possible to accommodate it nevertheless. Therefore a method is discussed to use flavour symmetries to distinguish between this possibility and new physics.