Search for CP violation in D0 and D+ decays

TL;DR

This study uses a large sample of charm decays to search for CP violation, finding results consistent with no CP violation and improving measurement precision over previous efforts.

Contribution

First high-statistics measurement of CP asymmetries in specific charm decays with improved precision and no observed CP violation.

Findings

CP asymmetries are consistent with zero within errors.

Measurement uncertainties are smaller than previous experiments.

No evidence of CP violation was observed in the studied decay modes.

Abstract

A high statistics sample of photoproduced charm particles from the FOCUS (E831) experiment at Fermilab has been used to search for CP violation in the Cabibbo suppressed decay modes D+ to K-K+pi+, D0 to K-K+ and D0 to pi-pi+. We have measured the following CP asymmetry parameters: A_CP(K-K+pi+) = +0.006 +/- 0.011 +/- 0.005, A_CP(K-K+) = -0.001 +/- 0.022 +/- 0.015 and A_CP(pi-pi+) = +0.048 +/- 0.039 +/- 0.025 where the first error is statistical and the second error is systematic. These asymmetries are consistent with zero with smaller errors than previous measurements.