Measurement of $D^{0}-\bar{D}^0$ mixing parameters and search for CP violation using $D^{0} \to K^{+}\pi^{-}$ decays

Information

LHCb-PAPER-2013-053
CERN-PH-EP-2013-176
arXiv:1309.6534 [PDF]

(Submitted on 25 Sep 2013)
Phys. Rev. Lett. 111 (2013) 251801
Inspire 1255432

Tools

Abstract

Measurements of charm mixing parameters from the decay-time-dependent ratio of D0->K+pi- to D0->K-pi+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb^{-1} of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP) symmetry, the mixing parameters are determined to be x'^2=(5.5 +- 4.9)x10^{-5}, y'= (4.8 +- 1.0)x10^{-3}, and R_D=(3.568 +- 0.066)x10^{-3}. Allowing for CP violation, the mixing parameters are determined separately for D0 and D0bar mesons yielding A_D = (-0.7 +- 1.9), for the direct CP-violating asymmetry, and 0.75 < |q/p|< 1.24 at the 68.3 confidence level, where q and p are parameters that describe the mass eigenstates of the neutral charm mesons in terms of the flavor eigenstates. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.

Figures and captions

Distribution of $ M( D ^0 \pi_{\rm s} ^+)$ for selected (a) right-sign $ D ^0 \rightarrow K^-\pi^+$ and (b) wrong-sign $ D ^0 \rightarrow K^+\pi^-$ candidates.	Fig1a.pdf [29 KiB] HiDef png [222 KiB] Thumbnail [196 KiB] *.C file
	Fig1b.pdf [29 KiB] HiDef png [252 KiB] Thumbnail [213 KiB] *.C file
Efficiency-corrected ratios of WS-to-RS yields for (a) $ D ^{+}$ decays, (b) $ D ^{-}$ decays, and (c) their differences as functions of decay time in units of $ D ^0$ lifetime. Projections of fits allowing for (dashed line) no $ C P$ violation, (dotted line) no direct $ C P$ violation, and (solid line) full $ C P$ violation are overlaid. The abscissa of the data points corresponds to the average decay time over the bin; the error bars indicate the statistical uncertainties.	Fig2.pdf [15 KiB] HiDef png [255 KiB] Thumbnail [237 KiB] *.C file
Two-dimensional confidence regions in the $(x'^2,y')$ plane obtained (a) without any restriction on $ C P$ violation, (b) assuming no direct $ C P$ violation, and (c) assuming $ C P$ conservation. The dashed (solid) curves in (a) and (b) indicate the contours of the mixing parameters associated with $\overline{ D }{} ^0$ ( $ D ^0$ ) decays. The best-fit value for $\overline{ D }{} ^0$ ( $ D ^0$ ) decays is shown with an open (filled) point. The solid, dashed, and dotted curves in (c) indicate the contours of $ C P$ -averaged mixing parameters at 68.3%, 95.5%, and 99.7% confidence level (CL), respectively. The best-fit value is shown with a point.	Fig3.pdf [18 KiB] HiDef png [163 KiB] Thumbnail [146 KiB] *.C file
Animated gif made out of all figures.	PAPER-2013-053.gif Thumbnail

Tables and captions

Results of fits to the data for different hypotheses on the $ C P$ symmetry. The reported uncertainties are statistical and systematic, respectively; ndf indicates the number of degrees of freedom. See App. A for fits results including correlation coefficients.	Table_1.pdf [53 KiB] HiDef png [315 KiB] Thumbnail [148 KiB] tex code
Detailed fit results. Reported uncertainties and correlation coefficients include both statistical and systematic sources.	Table_2.pdf [54 KiB] HiDef png [47 KiB] Thumbnail [19 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [845 KiB]
This archive contains extra figures related to LHCb-PAPER-2013-053 supplementary.pdf - A PDF file with all figures/tables and captions Fig.pdf - Figures in PDF format Fig.png - Figures in PNG format	Fig10.pdf [15 KiB] HiDef png [312 KiB] Thumbnail [196 KiB] *C file
	Fig11a.pdf [16 KiB] HiDef png [196 KiB] Thumbnail [207 KiB] *C file
	Fig11b.pdf [16 KiB] HiDef png [183 KiB] Thumbnail [184 KiB] *C file
	Fig12a.pdf [32 KiB] HiDef png [226 KiB] Thumbnail [188 KiB] *C file
	Fig12b.pdf [32 KiB] HiDef png [276 KiB] Thumbnail [226 KiB] *C file
	Fig12c.pdf [32 KiB] HiDef png [219 KiB] Thumbnail [188 KiB] *C file
	Fig12d.pdf [33 KiB] HiDef png [271 KiB] Thumbnail [228 KiB] *C file
	Fig13a.pdf [32 KiB] HiDef png [226 KiB] Thumbnail [195 KiB] *C file
	Fig13b.pdf [33 KiB] HiDef png [288 KiB] Thumbnail [237 KiB] *C file
	Fig13c.pdf [32 KiB] HiDef png [222 KiB] Thumbnail [196 KiB] *C file
	Fig13d.pdf [33 KiB] HiDef png [287 KiB] Thumbnail [240 KiB] *C file
	Fig14a.pdf [14 KiB] HiDef png [173 KiB] Thumbnail [156 KiB] *C file
	Fig14b.pdf [14 KiB] HiDef png [177 KiB] Thumbnail [155 KiB] *C file
	Fig4a.pdf [14 KiB] HiDef png [126 KiB] Thumbnail [68 KiB] *C file
	Fig4b.pdf [14 KiB] HiDef png [142 KiB] Thumbnail [81 KiB] *C file
	Fig4c.pdf [14 KiB] HiDef png [138 KiB] Thumbnail [81 KiB] *C file
	Fig5.pdf [15 KiB] HiDef png [171 KiB] Thumbnail [144 KiB] *C file
	Fig6.pdf [14 KiB] HiDef png [100 KiB] Thumbnail [56 KiB] *C file
	Fig7a.pdf [10 KiB] HiDef png [124 KiB] Thumbnail [110 KiB] *C file
	Fig7b.pdf [10 KiB] HiDef png [126 KiB] Thumbnail [112 KiB] *C file
	Fig8a.pdf [12 KiB] HiDef png [183 KiB] Thumbnail [170 KiB] *C file
	Fig8b.pdf [12 KiB] HiDef png [181 KiB] Thumbnail [169 KiB] *C file
	Fig9a.pdf [12 KiB] HiDef png [170 KiB] Thumbnail [160 KiB] *C file
	Fig9b.pdf [12 KiB] HiDef png [172 KiB] Thumbnail [160 KiB] *C file
	Fig9c.pdf [12 KiB] HiDef png [172 KiB] Thumbnail [160 KiB] *C file
	Fig9d.pdf [12 KiB] HiDef png [171 KiB] Thumbnail [161 KiB] *C file
	Fig9e.pdf [12 KiB] HiDef png [174 KiB] Thumbnail [164 KiB] *C file
	Fig9f.pdf [12 KiB] HiDef png [174 KiB] Thumbnail [162 KiB] *C file