Could Charm's "Third Time" Be the Real Charm? -- A Manifesto

TL;DR

This paper discusses the potential of charm meson decays, especially $D^0 - ar D^0$ oscillations, to reveal new physics beyond the Standard Model through CP violation studies, emphasizing promising channels and analysis methods.

Contribution

It provides a comprehensive analysis framework for CP symmetry in $D$ decays to identify potential signals of new physics beyond the Standard Model.

Findings

CP asymmetries are expected to be modest in the Standard Model

New Physics contributions could be significantly larger than SM effects in charm decays

Certain decay channels and multi-body final states are promising for observing CP violation

Abstract

The recent observation of $D^0 - \bar D^0$ oscillations has left us in a quandary concerning the theoretical interpretation: are they driven by SM forces alone or do they involve new dynamics? A comprehensive analysis of \cp symmetry in $D$ decays can probably resolve the issue. Charm studies might thus haul in their biggest prize yet: clear evidence for the intervention of New Physics. While the absolute size of \cp asymmetries will presumably be modest at best, SM contributions should be much smaller still. Thus the ratio of `signal' to `noise' -- i.e. NP over SM contributions -- might well be larger for $D$ than $B$ transitions. A typical list of promising channels is provided, most of which should be observable in a hadronic environment. Valuable lessons can be obtained by analyzing three- and four-body final states.