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Measurement of $C P$ violation in the phase space of $B^{\pm} \to K^{\pm} \pi^{+} \pi^{-}$ and $B^{\pm} \to K^{\pm} K^{+} K^{-}$ decays

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Abstract

The charmless decays $B^{\pm}\to K^{\pm}\pi^+\pi^-$ and $B^{\pm}\to K^{\pm}K^+K^-$ are reconstructed using data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by LHCb in 2011. The inclusive charge asymmetries of these modes are measured as $A_{C P}(B^{\pm}\to K^{\pm}\pi^+\pi^-) = 0.032 \pm 0.008 \stat \pm 0.004 \syst \pm 0.007 (J\psi K^{\pm})$ and $A_{C P}(B^{\pm}\to K^{\pm}K^+K^-) = -0.043 \pm 0.009 \stat \pm 0.003 \syst \pm 0.007 (J\psi K^{\pm})$, where the third uncertainty is due to the $C P$ asymmetry of the $B^{\pm}\to J\psi K^{\pm}$ reference mode. The significance of $A_{C P}(B^{\pm}\to K^{\pm}K^+K^-)$ exceeds three standard deviations and is the first evidence of an inclusive $C P$ asymmetry in charmless three-body $B$ decays. In addition to the inclusive $C P$ asymmetries, larger asymmetries are observed in localised regions of phase space.

Figures and captions

Invariant mass spectra of (a) $ { B ^\pm \rightarrow K ^\pm \pi ^+ \pi ^- }$ decays and (b) $ { B ^\pm \rightarrow K ^\pm K ^+ K ^- }$ decays. The left panel in each figure shows the $ B ^- $ modes and the right panel shows the $ B ^+ $ modes. The results of the unbinned maximum likelihood fits are overlaid. The main components of the fit are also shown.

 kpipi_[..].pdf [21 KiB]
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kpipi_fit_all.pdf
kkk_fi[..].pdf [17 KiB]
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kkk_fit_all.pdf

Asymmetries of the number of signal events in bins of the Dalitz plot, $ A_{ C P }^{N}$ , for (a) $ { B ^\pm \rightarrow K ^\pm \pi ^+ \pi ^- }$ and (b) $ { B ^\pm \rightarrow K ^\pm K ^+ K ^- }$ decays. The inset figures show the projections of the number of background-subtracted events in bins of (left) the $ m^2_{\pi ^+ \pi ^- }$ variable for $ m^2_{ K ^\pm \pi ^\mp } <15 {\mathrm{ Ge V^2 /}c^4} $ and (right) the $ m^2_{ K ^+ K ^- {\rm low}}$ variable for $ m^2_{ K ^+ K ^- {\rm high}} <15 {\mathrm{ Ge V^2 /}c^4} $. The distributions are not corrected for acceptance.

 kpipi_[..].pdf [21 KiB]
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kpipi_dalitz.pdf
kkk_dalitz.pdf [22 KiB]
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kkk_dalitz.pdf

Invariant mass spectra of (a) $ { B ^\pm \rightarrow K ^\pm \pi ^+ \pi ^- }$ decays in the region $0.08 < m^2_{\pi ^+ \pi ^- } < 0.66 {\mathrm{ Ge V^2 /}c^4} $ and $ m^2_{ K ^\pm \pi ^\mp } < 15 {\mathrm{ Ge V^2 /}c^4} $, and (b) $ { B ^\pm \rightarrow K ^\pm K ^+ K ^- }$ decays in the region $1.2 < m^2_{ K ^+ K ^- {\rm low}} < 2.0 {\mathrm{ Ge V^2 /}c^4} $ and $ m^2_{ K ^+ K ^- {\rm high}} < 15 {\mathrm{ Ge V^2 /}c^4} $. The left panel in each figure shows the $ B ^- $ modes and the right panel shows the $ B ^+ $ modes. The results of the unbinned maximum likelihood fits are overlaid.

 kpipi_[..].pdf [18 KiB]
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*.C file
kpipi_fit_region.pdf
kkk_fi[..].pdf [18 KiB]
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*.C file
kkk_fit_region.pdf

Animated gif made out of all figures.

 PAPER-2013-027.gif
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thumbnail_PAPER-2013-027.gif

Tables and captions

Systematic uncertainties on $ A_{ C P } ( { K ^\pm \pi ^+ \pi ^- } )$ and $ A_{ C P } ( { K ^\pm K ^+ K ^- } )$. The total systematic uncertainties are the sum in quadrature of the individual contributions.

 Table_1.pdf [31 KiB]
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tex code 		Table_1.pdf

Created on 27 April 2024.