Measurement of CP asymmetries in {D}_{(s)}^{+}to eta {pi}^{+} and {D}_{(s)}^{+}to {eta}^{prime }{pi}^{+} decays

Abstract

Searches for CP violation in the decays {D}_{(s)}^{+}to eta {pi}^{+} and {D}_{(s)}^{+}to {eta}^{prime }{pi}^{+} are performed using pp collision data corresponding to 6 fb−1 of integrated luminosity collected by the LHCb experiment. The calibration channels {D}_{(s)}^{+}to phi {pi}^{+} are used to remove production and detection asymmetries. The resulting CP-violating asymmetries areACP=D+→ηπ+=0.34±0.66±0.16±0.05%,ACP=Ds+→ηπ+=0.32±0.51±0.12%,ACP=D+→η′π+=0.49±0.18±0.06±0.05%,ACP=Ds+→η′π+=0.01±0.12±0.08%,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\displaystyle \\begin{array}{l}{\\mathcal{A}}^{CP}=\\left({D}^{+}\ o \\eta {\\pi}^{+}\\right)=\\left(0.34\\pm 0.66\\pm 0.16\\pm 0.05\\right)\\%,\\\\ {}{\\mathcal{A}}^{CP}=\\left({D}_s^{+}\ o \\eta {\\pi}^{+}\\right)=\\left(0.32\\pm 0.51\\pm 0.12\\right)\\%,\\\\ {}\\begin{array}{l}{\\mathcal{A}}^{CP}=\\left({D}^{+}\ o {\\eta}^{\\prime }{\\pi}^{+}\\right)=\\left(0.49\\pm 0.18\\pm 0.06\\pm 0.05\\right)\\%,\\\\ {}{\\mathcal{A}}^{CP}=\\left({D}_s^{+}\ o {\\eta}^{\\prime }{\\pi}^{+}\\right)=\\left(0.01\\pm 0.12\\pm 0.08\\right)\\%,\\end{array}\\end{array}} $$\\end{document}where the first uncertainty is statistical, the second is systematic and the third, relevant for the D+ channels, is due to the uncertainty on {mathcal{A}}^{CP}=left({D}^{+}to phi {pi}^{+}right) . These measurements, currently the most precise for three of the four channels considered, are consistent with the absence of CP violation. A combination of these results with previous LHCb measurements is presented.