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Precision measurement of $D$ meson mass differences

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Abstract

Using three- and four-body decays of $D$ mesons produced in semileptonic $b$-hadron decays, precision measurements of $D$ meson mass differences are made together with a measurement of the $D^{0}$ mass. The measurements are based on a dataset corresponding to an integrated luminosity of $1.0 fb^{-1}$ collected in $pp$ collisions at 7 TeV. Using the decay $D^0 \rightarrow K^{+} K^{-} K^{-} \pi^{+}$, the $D^0$ mass is measured to be $M(D^0) &=& 1864.75 \pm 0.15 \,({\rm stat}) \pm 0.11 \,({\rm syst}) \, \textrm{MeV/c^2}$. The mass differences $M(D^{+}) - M(D^{0}) = 4.76 \pm 0.12 \,({\rm stat}) \pm 0.07 \,({\rm syst}) \, \textrm{MeV/c^2}$ and $M(D^{+}_s) - M(D^{+}) = 98.68 \pm 0.03 \,({\rm stat}) \pm 0.04 \,({\rm syst}) \, \textrm{MeV/c^2}$ are measured using the $D^0 \rightarrow K^{+} K^{-} \pi^{+} \pi^{-}$ and $D^{+}_{(s)} \rightarrow K^{+}K^{-} \pi^{+}$ modes.

Figures and captions

Invariant mass distributions for the (a) $K^{+} K^{-} \pi^{+} \pi^{-} $ and (b) $K^{+} K^{-} K^{-} \pi^{+}$ final states. In each case the result of the fit described in the text is superimposed (solid line) together with the background component (dotted line). The pull, i.e. the difference between the fitted and measured value divided by the uncertainty on the measured value, is shown below each plot.

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Invariant mass distribution for the $K^{+} K^{-} \pi^{+}$ final state. The result of the fit described in the text is superimposed (solid line) together with the background component (dotted line). The pull, i.e. the difference between the fitted value and the measured value divided by the uncertainty, is shown below the plot.

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Measured $D^0$ mass versus $f$ as defined in Eq. 2. The (yellow) shaded area corresponds to a systematic uncertainty on the momentum scale of $0.03\,\%$ centred on the result for the $D^0 \rightarrow K^{+} K^{-} K^{-} \pi^{+}$ mode (horizontal dashed line). Only the $D^0 \rightarrow K^{+} K^{-} K^{-} \pi^{+}$ mode, where the systematic uncertainty is lowest, is used to determine the $D^0$ mass.

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Tables and captions

Signal yields, mass values, resolution scale factors and binned $\chi^2$/ndf (using 100 bins) obtained from the fits shown in Fig. 1 and Fig. 2 together with the values corrected for the effect of QED radiative corrections as described in the text.

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Systematic uncertainties (in \! $ {\mathrm{\,MeV\!/}c^2}$ ) on the mass measurements and on their differences.

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LHCb measurements, compared to the best previous measurements and to the results of a global fit to available open charm mass data. The quoted uncertainties are the quadratic sums of the statistical and systematic contributions. All values are in $ {\mathrm{\,MeV\!/}c^2}$ .

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Supplementary Material [file]

This ZIP file contains supplemetary material for the publication LHCb-PAPER-2013-013. The files are: Fig1.* D0 mass comparision Fig2.* D+ - D0 mass difference comparision Fig3.* Ds+ - D+ mass difference comparision Supplementary.pdf : An overview of the extra figures *.pdf, *.png, *.eps : The figures in variuous formats

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