Measurements of the absolute branching fractions of the doubly Cabibbo-suppressed decays $D^+\to K^+π^0$, $D^+\to K^+η$ and $D^+\to K^+η^{\prime}$

Abstract: Using $20.3\,\rm fb^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773\,GeV with the BESIII detector, we present improved measurements of the absolute branching fractions of the doubly Cabibbo-suppressed decays $D^+\to K^+\pi^0$, $D^+\to K^+\eta$ and $ D^+ \to K^+ \eta^{\prime}$ with the double-tag method. The statistical significance of each signal decay exceeds $10\sigma$. The branching fractions are determined to be ${\mathcal B}(D^+\to K^+ \pi^0) = (1.45 \pm 0.06 \pm 0.06)\times 10^{-4}$, ${\mathcal B}(D^+\to K^+ \eta) = (1.17 \pm 0.10 \pm 0.03)\times 10^{-4}$ and ${\mathcal B}(D^+\to K^+ \eta^{\prime}) = (1.88 \pm 0.15 \pm 0.06)\times 10^{-4}$, where the first uncertainties are statistical and the second systematic. These results are consistent with the world average values but with significantly improved precision.