Measurement of CP violation in the decay $B^{+}\to K^{+}{\pi }^0$

Abstract

A measurement of direct CP violation in the decay $B^{+}\to K^{+}{\pi }^0$ is reported using a data sample corresponding to an integrated luminosity of 5.4 ${\text{fb}}^{-1}$, collected with the LHCb experiment at a center-of-mass energy of $\sqrt{s}=13$ TeV. The CP asymmetry is measured to be $0.025\pm 0.015\pm 0.006\pm 0.003$, where the uncertainties are statistical, systematic, and due to an external input, respectively. This is the most precise measurement of the CP asymmetry in the decay $B^{+}\to K^{+}{\pi }^0$ and exceeds the precision on the current world average. This direct CP asymmetry is a key input to studies of a long-standing anomaly in $B$ meson decays, known as the $K\pi$-puzzle. The asymmetry is consistent with the previous measurements of this quantity, confirming and significantly enhancing the observed anomalous difference between the direct CP asymmetries of the $B^0\to K^{+}{\pi }^{-}$ and $B^{+}\to K^{+}{\pi }^0$ decays.

arXiv commentAll figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-040.html (LHCb public pages)

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