Abstract

A measurement of direct CP violation in the decay $B^{+} \rightarrow K^{+} \pi^{0}$ is reported using a data sample corresponding to an integrated luminosity of 5.4 $\textrm{fb}^{-1}$, 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 $B^{+} \rightarrow K^{+} \pi^{0}$ 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 $B^{0} \rightarrow K^{+} \pi^{-}$ and $B^{+} \rightarrow K^{+} \pi^{0}$ decays.

Figures and captions

Invariant-mass distribution of the selected candidates with fit projections overlayed. The data set is divided by the charge of the $B$ meson, with $B^+ \rightarrow K^+\pi^0$ shown on the left and $B^- \rightarrow K^-\pi^0$ on the right.	Fig1.eps [45 KiB] HiDef png [246 KiB] Thumbnail [233 KiB] *.C file
Animated gif made out of all figures.	PAPER-2020-040.gif Thumbnail

Tables and captions

Systematic uncertainties on $A_{ C P }( B ^+ \rightarrow K ^+ \pi ^0 )$.

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Supplementary Material [file]

Supplementary material full pdf	Supple[..].pdf [327 KiB]
This ZIP file contains supplemetary material for the publication LHCb-PAPER-2020-040. The files are: Supplementary.pdf : An overview of the extra figures Justification.pdf : PRL justification *.pdf, *.png, *.eps, *.C : The figures in various formats	Fig1-S.pdf [47 KiB] HiDef png [268 KiB] Thumbnail [213 KiB] *C file
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Created on 13 April 2024.