Measurement of the time-integrated $CP$ asymmetry in $D^0 \to K^0_S K^0_S$ decays

Information

LHCb-PAPER-2015-030
CERN-PH-EP-2015-215
arXiv:1508.06087 [PDF]

(Submitted on 25 Aug 2015)
JHEP 10 (2015) 055
Inspire 1389705

Tools

Abstract

The time-integrated $CP$ asymmetry in the decay $D^0 \to K^0_S K^0_S$ is measured using $3 fb^{-1}$ of proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The flavour of the $D^0$ meson is determined by use of the decay $D^{*+} \to D^0 \pi^+$ and its charge conjugate mode. The result is \[ {\cal A}_{CP} = -0.029 \pm 0.052 \pm 0.022, \] where the first uncertainty is statistical and the second systematic. The result is consistent with Standard Model expectations and improves the uncertainty with respect to the only previous measurement of this quantity by more than a factor of three.

Figures and captions

Distribution of $\Delta m$ for the control channel $ D ^0 \rightarrow K ^- \pi ^+ $ in (left) linear and in (right) logarithmic scale. The solid (black) line corresponds to the total fit, the dashed (blue) line corresponds to the background, and the dash-dotted (red) line represents the signal contribution.	Fig1a.pdf [40 KiB] HiDef png [218 KiB] Thumbnail [188 KiB] *.C file
	Fig1b.pdf [37 KiB] HiDef png [177 KiB] Thumbnail [141 KiB] *.C file
Distributions of $\Delta m$ split into (left) $ D ^{+}$ , (right) $ D ^{-}$ and (top) LL , (bottom) LLtrig , including the fit function. The solid (black) line corresponds to the total fit, the dashed (blue) line corresponds to the background, and the dash-dotted (red) line represents the signal contribution.	Fig2a.pdf [43 KiB] HiDef png [224 KiB] Thumbnail [190 KiB] *.C file
	Fig2b.pdf [43 KiB] HiDef png [210 KiB] Thumbnail [165 KiB] *.C file
	Fig2c.pdf [43 KiB] HiDef png [195 KiB] Thumbnail [163 KiB] *.C file
	Fig2d.pdf [42 KiB] HiDef png [194 KiB] Thumbnail [160 KiB] *.C file
Distributions of $\Delta m$ split into (left) $ D ^{+}$ , (right) $ D ^{-}$ and (top) LD , (bottom) DD , including the fit function. The solid (black) line corresponds to the total fit, the dashed (blue) line corresponds to the background, while the dash-dotted (red) line represents the signal contribution.	Fig3a.pdf [45 KiB] HiDef png [240 KiB] Thumbnail [214 KiB] *.C file
	Fig3b.pdf [44 KiB] HiDef png [228 KiB] Thumbnail [192 KiB] *.C file
	Fig3c.pdf [43 KiB] HiDef png [219 KiB] Thumbnail [192 KiB] *.C file
	Fig3d.pdf [43 KiB] HiDef png [237 KiB] Thumbnail [201 KiB] *.C file
Animated gif made out of all figures.	PAPER-2015-030.gif Thumbnail

Tables and captions

Definition of candidate categories.	Table_1.pdf [43 KiB] HiDef png [44 KiB] Thumbnail [18 KiB] tex code
Number of signal candidates and $ C P$ asymmetry obtained from the fits in the four categories.	Table_2.pdf [51 KiB] HiDef png [64 KiB] Thumbnail [32 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [173 KiB]
This ZIP file contains supplementary material for the publication LHCb-PAPER-2015-030. The files are: supplementary.pdf : An overview of the extra figures .pdf, .png, *.eps : The figures in various formats	Fig1a.pdf [15 KiB] HiDef png [106 KiB] Thumbnail [65 KiB] *C file
	Fig1b.pdf [15 KiB] HiDef png [111 KiB] Thumbnail [68 KiB] *C file
	Fig1c.pdf [15 KiB] HiDef png [103 KiB] Thumbnail [63 KiB] *C file
	Fig1d.pdf [14 KiB] HiDef png [104 KiB] Thumbnail [62 KiB] *C file
	Fig2a.pdf [16 KiB] HiDef png [107 KiB] Thumbnail [65 KiB] *C file
	Fig2b.pdf [16 KiB] HiDef png [117 KiB] Thumbnail [72 KiB] *C file
	Fig2c.pdf [14 KiB] HiDef png [100 KiB] Thumbnail [61 KiB] *C file
	Fig2d.pdf [14 KiB] HiDef png [101 KiB] Thumbnail [61 KiB] *C file