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Register a new userPrecision Measurement of the Mass of the $D^{*0}$ Meson and the Binding Energy of the $X(3872)$ Meson as a $D^0overline{D^{*0}}$ Molecule
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A precision measurement of the mass difference between the $D^0$ and $D^{*0}$ mesons has been made using 316~pb$^{-1}$ of $e^{+}e^{-}$ annihilation data taken at $sqrt{s}=4170$~MeV using the CLEO-c detector. We obtain $Delta M equiv M(D^{*0})-M(D^0) =142.007pm0.015$(stat)~$pm$~0.014(syst)~MeV, as the average for the two decays, $D^0to K^-pi^+$ and $D^0to K^-pi^+pi^-pi^+$. The new measurement of $Delta M$ leads to $M(D^{*0})=2006.850pm0.049$~MeV, and the currently most precise measurement of the binding energy of the ``exotic meson X(3872) if interpreted as a $D^0D^{*0}$ hadronic molecule, $E_{b}(text{X}(3872))equiv M(D^0D^{*0})-M(text{X}(3872))=3pm192$ keV.
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We present a study of $Bto X(3872)K$ with X(3872) decaying to $D^{*0}bar D^0$ using a sample of 657 million $Bbar B$ pairs recorded at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Both $D^{*0}to D^0gamma$ and $D^{*0}to D^0pi^0$ decay modes are used. We find a peak of $50.1^{+14.8}_{-11.1}$ events with a mass of $(3872.9^{+0.6 +0.4}_{-0.4 -0.5}){rm MeV}/c^2$, a width of $(3.9^{+2.8 +0.2}_{-1.4 -1.1}){rm MeV}/c^2$ and a product branching fraction ${cal B}(Bto X(3872)K)times{cal B}(X(3872)to D^{*0}bar D^0)=(0.80pm0.20pm0.10)times10^{-4}$, where the first errors are statistical and the second ones are systematic. The significance of the signal is $6.4sigma$. The difference between the fitted mass and the $D^{*0}bar D^0$ threshold is calculated to be $(1.1^{+0.6 +0.1}_{-0.4 -0.3}){rm MeV}/c^2$. We also obtain an upper limit on the product of branching fractions ${cal B}(Bto Y(3940)K)times{cal B}(Y(3940)to D^{*0}bar D^0)$ of $0.67times10^{-4}$ at 90% CL.
We report on a measurement of the flavor-specific $B^{0}_{s}$ lifetime and of the $D^{-}_{s}$ lifetime using proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to 3.0 fb$^{-1}$ of integrated luminosity. Approximately 407 000 $B^{0}_{s} rightarrow D^{(*)-}_{s} mu^{+} u_mu $ decays are partially reconstructed in the $K^{+}K^{-}pi^{-}mu^{+}$ final state. The $B^{0}_{s}$ and $D^{-}_{s}$ natural widths are determined using, as a reference, kinematically similar $B^{0} rightarrow D^{(*)-}mu^{+} u_mu$ decays reconstructed in the same final state. The resulting differences between widths of $B^{0}_{s}$ and $B^{0}$ mesons and of $D^{-}_{s}$ and $D^{-}$ mesons are $Delta_Gamma(B) =-0.0115 pm 0.0053 (stat) pm 0.0041 (syst)$ ps$^{-1}$ and $Delta_Gamma(D) = 1.0131 pm 0.0117 (stat) pm 0.0065 (syst)$ ps$^{-1}$, respectively. Combined with the known $B^{0}$ and $D^{-}$ lifetimes, these yield the flavor-specific $B^{0}_{s}$ lifetime, $tau^{rm fs}_{B^{0}_{s}} = 1.547 pm 0.013 (stat) pm 0.010 (syst) pm 0.004 (tau_{B})$ ps and the $D^{-}_{s}$ lifetime, $tau_{D^{-}_{s}} = 0.5064 pm 0.0030 (stat) pm 0.0017 (syst) pm 0.0017 (tau_{D})$ ps The last uncertainties originate from the limited knowledge of the $B^0$ and $D^{-}$ lifetimes. The results improve upon current determinations.
Using 482 pb$^{-1}$ of data taken at $sqrt{s}=4.009$ GeV, we measure the branching fractions of the decays of $D^{*0}$ into $D^0pi^0$ and $D^0gamma$ to be $BR(D^{*0} to D^0pi^0)=(65.5pm 0.8pm 0.5)%$ and $BR(D^{*0} to D^0gamma)=(34.5pm 0.8pm 0.5)%$ respectively, by assuming that the $D^{*0}$ decays only into these two modes. The ratio of the two branching fractions is $BR(D^{*0} to D^0pi^0)/BR(D^{*0} to D^0gamma) =1.90pm 0.07pm 0.05$, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of three compared to the present world average values.
We study $D^0overline{D}{}^0$ pairs produced in $e^+e^-$ collisions at $sqrt{s}=3.773$ GeV using a data sample of 2.92 fb$^{-1}$ collected with the BESIII detector. We measure the asymmetry $mathcal{A}^{CP}_{Kpi}$ of the branching fractions of $D to K^-pi^+$ in $CP$-odd and $CP$-even eigenstates to be $(12.7pm1.3pm0.7)times10^{-2}$. $mathcal{A}^{CP}_{Kpi}$ can be used to extract the strong phase difference $delta_{Kpi}$ between the doubly Cabibbo-suppressed process $overline{D}{}^{0}to K^-pi^+$ and the Cabibbo-favored process $D^0to K^- pi^+$. Using world-average values of external parameters, we obtain $cosdelta_{Kpi} = 1.02pm0.11pm0.06pm0.01$. Here, the first and second uncertainties are statistical and systematic, respectively, while the third uncertainty arises from the external parameters. This is the most precise measurement of $delta_{Kpi}$ to date.
We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type $D^0rightarrow h^{prime -} h^{-}ell^{prime +} ell^{+}$ and $D^0rightarrow h^{prime -} h^{+}ell^{primepm} ell^{mp}$, where $h$ and $h^{prime}$ represent a $K$ or $pi$ meson and $ell$ and $ell^{prime}$ an electron or muon. The analysis is based on $468$ fb$^{-1}$ of $e^+e^-$ annihilation data collected at or close to the $Y(4S)$ resonance with the BaBar detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes and we establish 90% confidence level upper limits on the branching fractions in the range $(1.0 - 30.6)times 10^{-7}$. The limits are between one and three orders of magnitude times more stringent than previous measurements.
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