Measurement of $y_{CP}$ in $D^0-\overline{D}^0$ oscillation using quantum correlations in $e^+e^-\to D^0\overline{D}^0$ at $\sqrt{s}$ = 3.773\,GeV

TL;DR

This paper measures the $y_{CP}$ parameter in $D^0-ar{D}^0$ oscillations using quantum correlations at threshold, providing a precise result consistent with previous measurements.

Contribution

First measurement of $y_{CP}$ in $D^0-ar{D}^0$ oscillations using quantum coherence at threshold energies.

Findings

Measured $y_{CP} = (-2.0 \u00b1 1.3 \u00b1 0.7)\u0025

Result compatible with world average

Utilized quantum coherence in $e^+e^-$ collisions at 3.773 GeV

Abstract

We report a measurement of the parameter $y_{CP}$ in $\ensuremath{D^0}\xspace-\ensuremath{\overline{D}^{0}}\xspace$ oscillations performed by taking advantage of quantum coherence between pairs of $\ensuremath{D^0}\xspace \ensuremath{\overline{D}^{0}}\xspace$ mesons produced in $e^+e^-$ annihilations near threshold. In this work, doubly-tagged $\ensuremath{D^0}\xspace \ensuremath{\overline{D}^{0}}\xspace$ events, where one $D$ decays to a $CP$ eigenstate and the other $D$ decays in a semileptonic mode, are reconstructed using a data sample of 2.92\,fb$^{-1}$ collected with the BESIII detector at the center-of-mass energy of $\sqrt{s}$ = 3.773\,GeV. We obtain $y_{CP} = (-2.0\pm1.3\pm0.7)\%$, where the first uncertainty is statistical and the second is systematic. This result is compatible with the current world average.