cern.ch

Measurement of the effective $B^0_s \rightarrow K^+K^-$ lifetime

[to restricted-access page]

Abstract

A measurement of the effective $B^0_s\rightarrow K^+K^-$ lifetime is presented using approximately $37 pb^{-1}$ of data collected by LHCb during 2010. This quantity can be used to put constraints on contributions from processes beyond the Standard Model in the $B^0_s$ meson system and is determined by two complementary approaches as $\tau_{B^0_s\to K^+K^-} = 1.440 \pm 0.096 (stat) \pm 0.008 (syst) \pm 0.003 (model) ps$.

Figures and captions

Results of the relative lifetime fit. Left: Fit to the time-integrated $KK$ mass spectrum. Right: Fit to the $KK$ decay time distribution. The black points show the total number of candidates per picosecond in each decay time bin, the stacked histogram shows the $ B ^0_ s \!\rightarrow K ^+ K ^- $ yield in red (dark) and the background yield in grey (light).

Figure[..].pdf [21 KiB]
HiDef png [261 KiB]
Thumbnail [93 KiB]
*.C file
Figure1Left.pdf
Figure[..].pdf [16 KiB]
HiDef png [240 KiB]
Thumbnail [68 KiB] *.C file
Figure1Right.pdf

Decay-time acceptance function for an event of a two-body hadronic decay. The light blue (shaded) regions show the bands for accepting the impact parameter of a track. The impact parameter of the negative track (IP2) is too small in (a) and lies within the accepted range in (b). The actual measured decay time lies in the accepted region. The acceptance intervals give conditional likelihoods used in the lifetime fit.

Figure[..].pdf [6 KiB]
HiDef png [110 KiB]
Thumbnail [27 KiB]
*.C file
Figure2Left.pdf
Figure[..].pdf [6 KiB]
HiDef png [132 KiB]
Thumbnail [33 KiB] *.C file
Figure2Right.pdf

Left: Average decay-time acceptance function for signal events, where the error band is an estimate of the statistical uncertainty. The plot is scaled to 1 at large decay times, not taking into account the total signal efficiency. Right: Decay-time distribution of the $ B ^0_ s \!\rightarrow K ^+ K ^- $ candidates and the fitted functions. The estimation of the background distribution is sensitive to fluctuations due to the limited statistics. Both plots are for the absolute lifetime measurement.

Figure[..].pdf [16 KiB]
HiDef png [76 KiB]
Thumbnail [33 KiB]
*.C file
Figure3Left.pdf
Figure[..].pdf [28 KiB]
HiDef png [152 KiB]
Thumbnail [59 KiB] *.C file
Figure3Right.pdf

Animated gif made out of all figures.

PAPER-2011-014.gif
Thumbnail
thumbnail_PAPER-2011-014.gif

Tables and captions

Summary of systematic uncertainties on the $ B ^0_ s \!\rightarrow K ^+ K ^- $ lifetime measurements.

Table_1.pdf [64 KiB]
HiDef png [87 KiB]
Thumbnail [13 KiB]
tex code
Table_1.pdf

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