Search for $CP$ violation in the phase space of $D^0 \to \pi^-\pi^+\pi^0$ decays with the energy test

TL;DR

This study searches for local $CP$ violation in the three-body decay of $D^0$ mesons using a model-independent energy test on LHCb data, finding no evidence of $CP$ violation.

Contribution

It introduces an unbinned, model-independent energy test method to probe local $CP$ violation in $D^0 o \pi^-\pi^+\pi^0$ decays using LHCb data.

Findings

Results are consistent with $CP$ symmetry.

Validated method with Cabibbo-favoured channel.

Sensitive to local $CP$ violation in phase space.

Abstract

A search for $CP$ violation in $D^0 \to \pi^-\pi^+\pi^0$ decays is reported, using $pp$ collision data collected by the LHCb experiment from 2015 to 2018 corresponding to an integrated luminosity of 6$fb^{-1}$. An unbinned model-independent approach provides sensitivity to local $CP$ violation within the two-dimensional phase space of the decay. The method is validated using the Cabibbo-favoured channel $\D^0 \to \K^-\pi^+\pi^0$ and background regions of the signal mode. The results are consistent with $CP$ symmetry in this decay.