Measurment of branching fractions and search for CP violation in D-0 -> pi(+)pi(-)eta, D-0 -> K+K-eta, and D-0 -> phi eta at Belle

We measure the branching fractions and CP asymmetries for the singly Cabibbo-suppressed decays D-0 -> pi(+)pi(-)eta, D-0 -> K+K-eta, and D-0 -> phi eta, using 980 fb(-1) of data from the Belle experiment at the KEKB e(+)e(-) collider. We obtain B(D-0 -> pi+pi-eta) = [1.22 +/- 0.02 (stat) +/- 0.02 (syst) +/- 0.03 (B-ref)] x 10(-3), B(D-0 -> K+K-eta) = [1.801(-0.06)(+0.07) (stat) +/- 0.04 (syst) +/- 0.05 (B-ref)] x 10(-4), B(D-0 -> phi eta) = [1.84 +/- 0.09 (stat) +/- 0.06 (syst) +/- 0.05 (B-ref)] x 10(-4), where the third uncertainty (B-ref) is from the uncertainty in the branching fraction of the reference mode D-0 -> K-pi(+)eta. The color-suppressed decay D-0 -> phi eta is observed for the first time, with very high significance. The results for the CP asymmetries are A(CP) (D-0 -> pi(+)pi(-)eta) = [0.9 +/- 1.2 (stat) +/- 0.5 (syst)]%, A(CP)(D-0 -> K+K-eta)=[-1.4 +/- 3.3 (stat) +/- 1.1 (syst)]%, A(CP)(D-0 -> phi eta) = [-1.9 +/- 4.4 (stat) +/- 0.6 (syst)]%. The results for D-0 -> pi(+)pi(-)eta are a significant improvement over previous results. The branching fraction and Acp results for D-0 -> K+K-eta, and the A(CP) result for D-0 -> phi eta, are the first such measurements. No evidence for CP violation is found in any of these decays. We thank the KEKB group for the excellent operation of the accelerator; the KEK cryogenics group for the efficient operation of the solenoid; and the KEK computer group, and the Pacific Northwest National Laboratory (PNNL) Environmental Molecular Sciences Laboratory (EMSL) computing group for strong computing support; and the National Institute of Informatics, and Science Information NETwork 5 (SINET5) for valuable network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, the Japan Society for the Promotion of Science (JSPS), and the Tau-Lepton Physics Research Center of Nagoya University; the Australian Research Council including grants DP180102629, DP170102389, DP170102204, DP150103061, FT130100303; Austrian Federal Ministry of Education, Science and Research (FWF) and FWF Austrian Science Fund No. P 31361-N36; the National Natural Science Foundation of China under Contracts No. 11435013, No. 11475187, No. 11521505, No. 11575017, No. 11675166, No. 11705209; Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS), Grant No. QYZDJ-SSW-SLH011; the CAS Center for Excellence in Particle Physics (CCEPP); the Shanghai Pujiang Program under Grant No. 18PJ1401000; the Shanghai Science and Technology Committee (STCSM) under Grant No. 19ZR1403000; the Ministry of Education, Youth and Sports of the Czech Republic under Contract No. LTT17020; Horizon 2020 ERC Advanced Grant No. 884719 and ERC Starting Grant No. 947006 "InterLeptons" (European Union); the Carl Zeiss Foundation, the Deutsche Forschungsgemeinschaft, the Excellence Cluster Universe, and the VolkswagenStiftung; the Department of Atomic Energy (Project Identification No. RTI 4002) and the Department of Science and Technology of India; the Istituto Nazionale di Fisica Nucleare of Italy; National Research Foundation (NRF) of Korea Grant Nos. 2016R1D1A1B01010135, 2016R1D1A1B02012900, 2018R1A2B3003643, 2018R1A6A1A06024970, 2018R1D1A1B07047294, 2019K1A3A7A09033840, 2019R1I1A3A01058933; Radiation Science Research Institute, Foreign Large-size Research Facility Application Supporting project, the Global Science Experimental Data Hub Center of the Korea Institute of Science and Technology Information and KREONET/GLORIAD; the Polish Ministry of Science and Higher Education and the National Science Center; the Ministry of Science and Higher Education of the Russian Federation, Agreement 14.W03.31.0026, and the HSE University Basic Research Program, Moscow; University of Tabuk research grants S-1440-0321, S-0256-1438, and S-0280-1439 (Saudi Arabia); the Slovenian Research Agency Grant Nos. J1-9124 and P1-0135; Ikerbasque, Basque Foundation for Science, Spain; the Swiss National Science Foundation; the Ministry of Education and the Ministry of Science and Technology of Taiwan; and the United States Department of Energy and the DYNational Science Foundation.