Search for CP violation in {D}_{(s)}^{+}to {h}^{+}{pi}^0 and {D}_{(s)}^{+}to {h}^{+}eta decays

Abstract

Searches for CP violation in the two-body decays {D}_{(s)}^{+}to {h}^{+}{pi}^0 and {D}_{(s)}^{+}to {h}^{+}eta (where h+ denotes a π+ or K+ meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb−1 or 6 fb−1 of integrated luminosity. The π0 and η mesons are reconstructed using the e+e−γ final state, which can proceed as three-body decays π0→ e+e−γ and η → e+e−γ, or via the two-body decays π0→ γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes {D}_{(s)}^{+}to {K}_{mathrm{S}}^0{h}^{+} to cancel the production and detection asymmetries. The CP asymmetries are measured to beACPD+→π+π0=−1.3±0.9±0.6%,ACPD+→K+π0=−3.2±4.7±2.1%,ACPD+→π+η=−0.2±0.8±0.4%,ACPD+→K+η=−6±10±4%,ACPDs+→K+π0=−0.8±3.9±1.2%,ACPDs+→π+η=0.8±0.7±0.5%,ACPDs+→K+η=0.9±3.7±1.1%,\\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}$$ {\\displaystyle \\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {\\pi}^{+}{\\pi}^0\\right)=\\left(-1.3\\pm 0.9\\pm 0.6\\right)\\%,\\\\ {}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {K}^{+}{\\pi}^0\\right)=\\left(-3.2\\pm 4.7\\pm 2.1\\right)\\%,\\\\ {}\\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {\\pi}^{+}\\eta \\right)=\\left(-0.2\\pm 0.8\\pm 0.4\\right)\\%,\\\\ {}{\\mathcal{A}}_{CP}\\left({D}^{+}\\to {K}^{+}\\eta \\right)=\\left(-6\\pm 10\\pm 4\\right)\\%,\\\\ {}\\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}_s^{+}\\to {K}^{+}{\\pi}^0\\right)=\\left(-0.8\\pm 3.9\\pm 1.2\\right)\\%,\\\\ {}\\begin{array}{c}{\\mathcal{A}}_{CP}\\left({D}_s^{+}\\to {\\pi}^{+}\\eta \\right)=\\left(0.8\\pm 0.7\\pm 0.5\\right)\\%,\\\\ {}{\\mathcal{A}}_{CP}\\left({D}_s^{+}\\to {K}^{+}\\eta \\right)=\\left(0.9\\pm 3.7\\pm 1.1\\right)\\%,\\end{array}\\end{array}\\end{array}\\end{array}} $$\\end{document}where the first uncertainties are statistical and the second systematic. These results are consistent with no CP violation and mostly constitute the most precise measurements of {mathcal{A}}_{CP} in these decay modes to date.