Measurement of branching fractions and search for CP violation in D0 → π+π−η, D0 → K+K−η, and D0 → ϕη at Belle

Abstract

We measure the branching fractions and CP asymmetries for the singly Cabibbo-suppressed decays D0 → π+π−η, D0 → K+K−η, and D0 → ϕη, using 980 fb−1 of data from the Belle experiment at the KEKB e+e− collider. We obtain$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({D}^0\to {\pi}^{+}{\pi}^{-}\eta \right)=\left[1.22\pm 0.02\left(\mathrm{stat}\right)\pm 0.02\left(\mathrm{syst}\right)\pm 0.03\left({\mathcal{B}}_{\mathrm{ref}}\right)\right]\times {10}^{-3},\\ {}\mathcal{B}\left({D}^0\to {K}^{+}{K}^{-}\eta \right)=\left[{1.80}_{-0.06}^{+0.07}\left(\mathrm{stat}\right)\pm 0.04\left(\mathrm{syst}\right)\pm 0.05\left({\mathcal{B}}_{\mathrm{ref}}\right)\right]\times {10}^{-4},\\ {}\mathcal{B}\left({D}^0\to \phi \eta \right)=\left[1.84\pm 0.09\left(\mathrm{stat}\right)\pm 0.06\left(\mathrm{syst}\right)\pm 0.05\left({\mathcal{B}}_{\mathrm{ref}}\right)\right]\times {10}^{-4},\end{array}} $$ B D 0 → π + π − η = 1.22 ± 0.02 stat ± 0.02 syst ± 0.03 B ref × 10 − 3 , B D 0 → K + K − η = 1.80 − 0.06 + 0.07 stat ± 0.04 syst ± 0.05 B ref × 10 − 4 , B D 0 → ϕη = 1.84 ± 0.09 stat ± 0.06 syst ± 0.05 B ref × 10 − 4 , where the third uncertainty ($$ \mathcal{B} $$ B ref) is from the uncertainty in the branching fraction of the reference mode D0 → K−π+η. The color-suppressed decay D0 → ϕη is observed for the first time, with very high significance. The results for the CP asymmetries are$$ {\displaystyle \begin{array}{c}{A}_{CP}\left({D}^0\ {\pi}^{+}{\pi}^{-}\eta \right)=\left[0.9\pm 1.2\left(\mathrm{stat}\right)\pm 0.5\left(\mathrm{syst}\right)\right]\%,\\ {}{A}_{CP}\left({D}^0\to {K}^{+}{K}^{-}\eta \right)=\left[-1.4\pm 3.3\left(\mathrm{stat}\right)\pm 1.1\left(\mathrm{syst}\right)\right]\%,\\ {} ACP\ \left({D}^0\to \phi \eta \right)=\left[-1.9\pm 4.4\left(\mathrm{stat}\right)\pm 0.6\left(\mathrm{syst}\right)\right]\%.\end{array}} $$ A CP D 0 π + π − η = 0.9 ± 1.2 stat ± 0.5 syst % , A CP D 0 → K + K − η = − 1.4 ± 3.3 stat ± 1.1 syst % , ACP D 0 → ϕη = − 1.9 ± 4.4 stat ± 0.6 syst % . The results for D0 → π+π−η are a significant improvement over previous results. The branching fraction and ACP results for D0 → K+K−η, and the ACP result for D0 → ϕη, are the first such measurements. No evidence for CP violation is found in any of these decays.

Study of Branching fraction and CP Asymmetry of charm mesons at Belle

“…This paper [10] reports the branching fraction of Cabibbo suppressed 𝐷 0 → 𝜋 + 𝜋 − 𝜂, 𝐷 0 → 𝐾 + 𝐾 − 𝜂 and 𝐷 0 → 𝜙𝜂 decays relative to the normalization mode 𝐷 0 → 𝐾 − 𝜋 + 𝜂 using 988 fb −1 of Belle data set. The signal yield is determined via a one-dimensional unbinned extended maximum-likelihood fit to the variable 𝑄, where…”

“…The Belle experiment collected a total of 1 ab −1 of data, which includes 1.3 × 10 9 𝑐 c events. In this proceeding, we report the recent charm results from the Belle experiment including; a) Measurement of the branching fraction (B) and search for CPV in the SCS decay 𝐷 0 → 𝐾 0 𝑆 𝐾 0 𝑆 𝜋 + 𝜋 − [9]; b) the measurement of branching fraction and search for CPV in 𝐷 0 → 𝜋 + 𝜋 − 𝜂, 𝐷 0 → 𝐾 + 𝐾 − 𝜂, 𝐷 0 → 𝜙𝜂 [10]; and c) the measurement of branching fractions for 𝐷 → 𝐾 ℎ𝜋𝜋 0 (ℎ = 𝜋, 𝐾) decays [11].…”