Standard Model prediction and new physics tests for D0 -> h+h-l+l- (h=\pi,K; l=e,\mu)

TL;DR

This paper analyzes D0 -> h+h-l+l- decays, exploring long-distance effects, resonance contributions, and angular asymmetries to identify potential signals of new physics, especially in CP-violation contexts.

Contribution

It provides a comprehensive study of decay mechanisms, resonance effects, and asymmetries, highlighting new physics signatures in D0 decays not previously detailed.

Findings

Resonant effects dominate mu+mu- decay modes.

Branching ratios approach LHCb sensitivity.

Asymmetries involving Q_{10} can reveal new physics.

Abstract

Motivated by the recent evidence for direct CP-violation in D0 -> h+h- decays, we provide an exhaustive study of both Cabibbo-favored and Cabibbo-suppressed (singly and doubly) D0 -> h1+h2-l+l- decays. In particular, we study the Dalitz plot for the long-distance contributions in the (m_{ll}^2,m_{hh}^2) parameter space. We find that near-resonant effects, i.e., D0 -> V(h1+h2-)l+l- with V=\rho,K*,\phi, are sizeable and even dominant (over Bremsstrahlung) for the \mu+\mu- decay modes, bringing the branching ratios close to the LHCb reach. We also provide a detailed study of the angular asymmetries for such decays and identify signatures for new physics detection. In particular, new physics signals can be neatly isolated in asymmetries involving the semileptonic operator Q_{10}, where for typical new physics scenarios the effects can be as sizeable as O(1%) for the doubly Cabibbo-suppressed modes.