Observation of $D^+\to\eta\eta\pi^+$ and improved measurement of $D^{0(+)}\to\eta\pi^+\pi^{-(0)}$

TL;DR

This paper reports the first observation of the decay $D^+\to\eta\eta\pi^+$ and provides improved measurements of branching fractions for several $D$ meson decays using BESIII data, with no evidence of CP violation.

Contribution

The study presents the first observation of the $D^+\to\eta\eta\pi^+$ decay and offers more precise measurements of related $D$ meson decay branching fractions.

Findings

First observation of $D^+\to\eta\eta\pi^+$ decay.

Measured branching fractions with improved precision.

No evidence of CP violation in studied decays.

Abstract

Using an $e^+e^-$ annihilation data sample corresponding to an integrated luminosity of $2.93\,\rm fb^{-1}$ collected at the center-of-mass energy of 3.773\,GeV with the BESIII detector, we measure the absolute branching fractions of $D^+\to\eta\eta\pi^+$, $D^+\to\eta\pi^+\pi^0$, and $D^0\to\eta\pi^+\pi^-$ to be $(2.96 \pm 0.24 \pm 0.13)\times 10^{-3}$, $(2.23 \pm 0.15 \pm 0.11)\times 10^{-3}$, and $(1.20 \pm 0.07 \pm 0.04)\times 10^{-3}$, respectively, where the first uncertainties are statistical and the second ones systematic. The $D^+\to\eta\eta\pi^+$ decay is observed for the first time and the branching fractions of $D^{+(0)}\to\eta\pi^+\pi^{0(-)}$ are measured with much improved precision. In addition we test for $CP$ asymmetries in the separated charge-conjugate branching fractions; no evidence of $CP$ violation is found.