Measurement of the charm-mixing parameter $y_{CP}$

Information

LHCb-PAPER-2018-038
CERN-EP-2018-270
arXiv:1810.06874 [PDF]

(Submitted on 16 Oct 2018)
Phys. Rev. Lett. 122 (2019) 011802
Inspire 1698962

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Abstract

A measurement of the charm-mixing parameter $y_{CP}$ using $D^0 \to K^+ K^-$, $D^0 \to \pi^+ \pi^-$, and $D^0 \to K^- \pi^+$ decays is reported. The $D^0$ mesons are required to originate from semimuonic decays of $B^-$ and $\overline{B}^0$ mesons. These decays are partially reconstructed in a data set of proton-proton collisions at center-of-mass energies of 7 and 8 TeV collected with the LHCb experiment and corresponding to an integrated luminosity of 3 fb$^{-1}$. The $y_{CP}$ parameter is measured to be $(0.57 \pm 0.13(\rm{stat.}) \pm 0.09(\rm{syst.}))\%$, in agreement with, and as precise as, the current world-average value.

Figures and captions

Distribution of $ D ^0$ mass for candidates passing the selection with fit projections overlaid: (top) $ D ^0 \rightarrow K^+K^-$ decays, (center) $ D ^0 \rightarrow \pi^+\pi^-$ decays, and (bottom) $ D ^0 \rightarrow K^-\pi^+$ decays.	Fig1.pdf [27 KiB] HiDef png [263 KiB] Thumbnail [219 KiB] *.C file
Ratio of decay-time acceptances from simulation for (top) $ D ^0 \rightarrow K^+K^-$ over $ D ^0 \rightarrow K^-\pi^+$ decays and (bottom) $ D ^0 \rightarrow \pi^+\pi^-$ over $ D ^0 \rightarrow K^-\pi^+$ decays.	Fig2.pdf [18 KiB] HiDef png [114 KiB] Thumbnail [61 KiB] *.C file
Acceptance-corrected signal-yield ratio of (top) $ D ^0 \rightarrow K^+K^-$ over $ D ^0 \rightarrow K^-\pi^+$ decays and (bottom) $ D ^0 \rightarrow \pi^+\pi^-$ over $ D ^0 \rightarrow K^-\pi^+$ decays as a function of $ D ^0$ decay time, with fit projection overlaid.	Fig3.pdf [18 KiB] HiDef png [140 KiB] Thumbnail [138 KiB] *.C file
Animated gif made out of all figures.	PAPER-2018-038.gif Thumbnail

Tables and captions

Signal yields of the selected candidates.	Table_1.pdf [60 KiB] HiDef png [76 KiB] Thumbnail [36 KiB] tex code
Measured values of $\Delta_\Gamma$ and $ y_{ C P }$ . The first uncertainty is statistical, the second is systematic.	Table_2.pdf [67 KiB] HiDef png [30 KiB] Thumbnail [16 KiB] tex code

Supplementary Material [file]

This ZIP file contains supplemetary material for the publication LHCb-PAPER-2018-XXX. The files are: Supplementary-LHCb-PAPER-2018-XXX.pdf : An overview of the extra figures .pdf, .png, .eps, .C : The figures in various formats	Fig10.pdf [18 KiB] HiDef png [149 KiB] Thumbnail [151 KiB] *C file
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