Measurement of the time-integrated CP asymmetry in D0\u2009\u2192\u2009KS0KS0 decays

Abstract

A measurement of the time-integrated CP asymmetry in D0 → KS0KS0 decays is reported. The data correspond to an integrated luminosity of about 2 fb−1 collected in 2015–2016 by the LHCb collaboration in pp collisions at a centre-of-mass energy of 13 TeV. The D0 candidate is required to originate from a D*+ → D0π+ decay, allowing the determination of the flavour of the D0 meson using the pion charge. The D0 → K+K− decay, which has a well measured CP asymmetry, is used as a calibration channel. The CP asymmetryfor D0 → KS0KS0 is measured to beACPD0→KS0KS0=4.3±3.4±1.0%,\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ {\\mathcal{A}}^{CP}\\left({D}^0\\to {K}_S^0{K}_S^0\\right)=\\left(4.3\\pm 3.4\\pm 1.0\\right)\\%, $$\\end{document}where the first uncertainty is statistical and the second is systematic. This result is combined with the previous LHCb measurement at lower centre-of-mass energies to obtainACPD0→KS0KS0=2.3±2.8±0.9%.\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ {\\mathcal{A}}^{CP}\\left({D}^0\\to {K}_S^0{K}_S^0\\right)=\\left(2.3\\pm 2.8\\pm 0.9\\right)\\%. $$\\end{document}