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

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Abstract

The charmless decays $B^{\pm} \rightarrow K^{+}K^{-}\pi^{\pm}$ and $B^{\pm} \rightarrow \pi^{+}\pi^{-}\pi^{\pm}$ are reconstructed in a data set, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of pp collisions at a center-of-mass energy of 7 TeV, collected by LHCb in 2011. The inclusive charge asymmetries of these modes are measured to be $A_{CP}(B^{\pm} \rightarrow K^{+}K^{-}\pi^{\pm}) =-0.141 \pm 0.040 (stat) \pm 0.018 (syst) \pm 0.007 (J/\psi K^{\pm})$ and $A_{CP}(B^{\pm} \rightarrow \pi^{+}\pi^{-}\pi^{\pm}) = 0.117 \pm 0.021 (stat) \pm 0.009 (syst) \pm 0.007 (J/\psi K^{\pm})$, where the third uncertainty is due to the CP asymmetry of the $B^{\pm} \rightarrow J/\psi K^{\pm}$ reference mode. In addition to the inclusive CP asymmetries, larger asymmetries are observed in localized regions of phase space.

Figures and captions

Invariant mass spectra of (a) $ { B ^\pm \to \pi ^+ \pi ^- \pi ^\pm }$ decays and (b) $ { B ^\pm \to K ^+ K ^- \pi ^\pm }$ 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.

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

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Invariant mass spectra of (a) $ { B ^\pm \to \pi ^+ \pi ^- \pi ^\pm }$ decays in the region $ m^2_{\pi ^+ \pi ^- {\rm low}} < 0.4 {\mathrm{ Ge V^2 /}c^4} $ and $ m^2_{\pi ^+ \pi ^- {\rm high}} > 15 {\mathrm{ Ge V^2 /}c^4} $, and (b) $ { B ^\pm \to K ^+ K ^- \pi ^\pm }$ decays in the region $ m^2_{ K ^+ K ^- } < 1.5 {\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.

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Fig3b.pdf [44 KiB]
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Animated gif made out of all figures.

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Tables and captions

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

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Created on 27 April 2024.