Measurement of the charge asymmetry in $B^{\pm}\rightarrow \phi K^{\pm}$ and search for $B^{\pm}\rightarrow \phi \pi^{\pm}$ decays

Information

LHCb-PAPER-2013-048
CERN-PH-EP-2013-166
arXiv:1309.3742 [PDF]

(Submitted on 15 Sep 2013)
Phys. Lett. B728 (2014) 85
Inspire 1254225

Tools

Abstract

The \CP-violating charge asymmetry in $B^{\pm}\rightarrow \phi K^{\pm}$ decays is measured in a sample of $pp$ collisions at 7 TeV centre-of-mass energy, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ collected by the LHCb experiment. The result is $\mathcal{A}_{CP}(B^{\pm}\rightarrow \phi K^{\pm}) = \rm 0.022\pm 0.021 \pm 0.009$, where the first uncertainty is statistical and the second systematic. In addition, a search for the $B^{\pm}\rightarrow \phi \pi^{\pm}$ decay mode is performed, using the $B^{\pm}\rightarrow \phi K^{\pm}$ decay rate for normalization. An upper limit on the branching fraction $\mathcal{B}(B^{\pm}\rightarrow \phi \pi^{\pm})< 1.5\times 10^{-7}$ is set at 90 confidence level.

Figures and captions

Lowest-order Feynman diagrams of the Standard Model for the decays $ B ^+ \rightarrow \phi K ^+ $ (top) and $ B ^+ \rightarrow \phi\pi ^+ $ (bottom). The diagrams with an external $\phi$ meson are OZI suppressed.	BPHIK_2.pdf [128 KiB] HiDef png [34 KiB] Thumbnail [18 KiB] *.C file
	BPHIK.pdf [137 KiB] HiDef png [46 KiB] Thumbnail [24 KiB] *.C file
	BPHIPI.pdf [153 KiB] HiDef png [46 KiB] Thumbnail [24 KiB] *.C file
Distributions of the (a) $ K ^+ K ^- K ^- $ and (b) $ K ^+ K ^- $ masses of the selected $ B ^- \rightarrow \phi K ^- $ candidates, as well as of the (c) $ K ^+ K ^- K ^+ $ and (d) $ K ^+ K ^- $ masses of the selected $ B ^+ \rightarrow \phi K ^+ $ candidates. The solid blue curves represent the result of the simultaneous fit described in the text, with the following components: $ B ^\pm \rightarrow \phi K ^\pm $ signal (dotted red), nonresonant $ B ^\pm \rightarrow K ^+ K ^- K ^\pm $ background (dashed red), partially-reconstructed $b$-hadron background with (dotted blue) or without (dashed blue) a true $\phi$ meson, and combinatorial background with (dotted green) or without (dashed green) a true $\phi$ meson. Some of the components are barely visible because the corresponding yields are small. Normalized residuals are displayed below each histogram.	BMass_[..].pdf [23 KiB] HiDef png [250 KiB] Thumbnail [206 KiB] *.C file
	PhiMas[..].pdf [23 KiB] HiDef png [237 KiB] Thumbnail [201 KiB] *.C file
	BMass_[..].pdf [23 KiB] HiDef png [251 KiB] Thumbnail [207 KiB] *.C file
	PhiMas[..].pdf [23 KiB] HiDef png [236 KiB] Thumbnail [198 KiB] *.C file
Distributions of the (a, c) $ K ^+ K ^- \pi ^\pm $ and (b, d) $ K ^+ K ^- $ masses of the selected $ B ^\pm \rightarrow \phi\pi ^\pm $ candidates, shown both with linear and logarithmic scales. The solid blue curves represent the result of the simultaneous fit described in the text, with the following components: $ B ^\pm \rightarrow \phi\pi ^\pm $ signal (dotted black), nonresonant $ B ^\pm \rightarrow K ^+ K ^- \pi ^\pm $ background (dashed black), $ B ^\pm \rightarrow \phi K ^\pm $ signal (dotted red), nonresonant $ B ^\pm \rightarrow K ^+ K ^- K ^\pm $ background (dashed red), partially-reconstructed $b$-hadron background with (dotted blue) or without (dashed blue) a true $\phi$ meson, and combinatorial background with (dotted green) or without (dashed green) a true $\phi$ meson. Normalized residuals are displayed below the histograms.	BMassP[..].pdf [39 KiB] HiDef png [213 KiB] Thumbnail [180 KiB] *.C file
	PhiMas[..].pdf [37 KiB] HiDef png [207 KiB] Thumbnail [183 KiB] *.C file
	BMassP[..].pdf [23 KiB] HiDef png [260 KiB] Thumbnail [220 KiB] *.C file
	PhiMas[..].pdf [25 KiB] HiDef png [245 KiB] Thumbnail [215 KiB] *.C file
Animated gif made out of all figures.	PAPER-2013-048.gif Thumbnail

Tables and captions

Raw charge asymmetries for the $ B ^\pm \rightarrow \phi K ^\pm $ and $ B ^\pm \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^\pm $ decays, their difference $\Delta \mathcal{A}_{C P}$, and the fraction of $ B ^\pm \rightarrow \phi K ^\pm $ signal events in each trigger subsample for $k = \rm TOS, TIS$. All uncertainties are statistical only.	Table_1.pdf [56 KiB] HiDef png [63 KiB] Thumbnail [31 KiB] tex code
Systematic uncertainties on the measurement of $\Delta\mathcal{A}_{C P}$.	Table_2.pdf [17 KiB] HiDef png [76 KiB] Thumbnail [33 KiB] tex code

Supplementary Material [file]

	Fig4a.pdf [22 KiB] HiDef png [252 KiB] Thumbnail [211 KiB] *C file
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	Fig5b.pdf [39 KiB] HiDef png [207 KiB] Thumbnail [162 KiB] *C file
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	Supple[..].pdf [492 KiB] HiDef png [601 KiB] Thumbnail [351 KiB] *C file