cern.ch

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

[to restricted-access page]

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]
HiDef png [350 KiB]
Thumbnail [91 KiB]
*.C file
kpipi_fit_all.pdf
kkk_fi[..].pdf [17 KiB]
HiDef png [264 KiB]
Thumbnail [76 KiB] *.C file
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{\,GeV^2\!/}c^4} $ and (right) the $ m^2_{ K ^+ K ^- \,{\rm low}}$ variable for $ m^2_{ K ^+ K ^- \,{\rm high}} <15 {\mathrm{\,GeV^2\!/}c^4} $. The distributions are not corrected for acceptance.

kpipi_[..].pdf [21 KiB]
HiDef png [240 KiB]
Thumbnail [93 KiB]
*.C file
kpipi_dalitz.pdf
kkk_dalitz.pdf [22 KiB]
HiDef png [247 KiB]
Thumbnail [99 KiB] *.C file
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{\,GeV^2\!/}c^4} $ and $ m^2_{ K ^\pm \pi ^\mp } < 15 {\mathrm{\,GeV^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{\,GeV^2\!/}c^4} $ and $ m^2_{ K ^+ K ^- \,{\rm high}} < 15 {\mathrm{\,GeV^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]
HiDef png [322 KiB]
Thumbnail [100 KiB]
*.C file
kpipi_fit_region.pdf
kkk_fi[..].pdf [18 KiB]
HiDef png [276 KiB]
Thumbnail [78 KiB] *.C file
kkk_fit_region.pdf

Animated gif made out of all figures.

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

Tables and captions

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

Table_I.pdf [37 KiB]
HiDef png [80 KiB]
Thumbnail [11 KiB]
tex code
Table_I.pdf

Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.