Showing papers by "J. S. Lange published in 2005"

Improved measurement ofCP-violation parameterssin2ϕ1and|λ|,Bmeson lifetimes, andB0-B¯0mixing parameterΔmd

Abstract: We present a precise measurement of the standard model $CP$-violation parameter $\mathrm{sin} 2{\ensuremath{\phi}}_{1}$, the direct $CP$ violation parameter $|\ensuremath{\lambda}|$, the lifetimes of charged and neutral $B$ mesons and their ratio, and the ${B}^{0}$-${\overline{B}}^{0}$ mixing parameter $\ensuremath{\Delta}{m}_{d}$ based on a sample of $152\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. One of two $B$ mesons is fully reconstructed in a $CP$-eigenstate or a flavor-eigenstate decay channel. The flavor of the accompanying $B$ meson is identified from its decay products. From the distributions of the time interval between the two $B$ meson decay points, we obtain $\mathrm{sin} 2{\ensuremath{\phi}}_{1}=0.728\ifmmode\pm\else\textpm\fi{}0.056(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.023(\mathrm{syst})$, $|\ensuremath{\lambda}|=1.007\ifmmode\pm\else\textpm\fi{}0.041(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.033(\mathrm{syst})$, ${\ensuremath{\tau}}_{{B}^{0}}=[1.534\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.010(\mathrm{syst})]\text{ }\text{ }\mathrm{ps}$, ${\ensuremath{\tau}}_{{B}^{+}}=[1.635\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{syst})]\text{ }\text{ }\mathrm{ps}$, ${\ensuremath{\tau}}_{{B}^{+}}/{\ensuremath{\tau}}_{{B}^{0}}=1.066\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{syst})$ and $\ensuremath{\Delta}{m}_{d}=[0.511\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.006{(\mathrm{syst})]\text{ }\text{ }\mathrm{ps}}^{\ensuremath{-}1}$. The results for $\mathrm{sin} 2{\ensuremath{\phi}}_{1}$ and $|\ensuremath{\lambda}|$ are consistent with the standard model expectations. The significance of the observed deviation from unity in the lifetime ratio exceeds 5 standard deviations.

Observation ofB+→K1(1270)+γ

Abstract: We report the observation of the radiative decay ${B}^{+}\ensuremath{\rightarrow}{K}_{1}(1270{)}^{+}\ensuremath{\gamma}$ using a data sample of $140\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ taken at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. We find the branching fraction to be $\mathcal{B}\mathbf{(}{B}^{+}\ensuremath{\rightarrow}{K}_{1}(1270{)}^{+}\ensuremath{\gamma}\mathbf{)}=\mathbf{(}4.3\ifmmode\pm\else\textpm\fi{}0.9(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.9(\mathrm{syst}.)\mathbf{)}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ with a significance of $7.3\ensuremath{\sigma}$. We find no significant signal for ${B}^{+}\ensuremath{\rightarrow}{K}_{1}(1400{)}^{+}\ensuremath{\gamma}$ and set an upper limit $\mathcal{B}\mathbf{(}{B}^{+}\ensuremath{\rightarrow}{K}_{1}(1400{)}^{+}\ensuremath{\gamma}\mathbf{)}l1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at the 90% confidence level. We also measure inclusive branching fractions for ${B}^{+}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$ and ${B}^{0}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$ in the mass range $1\text{ }\text{ }\mathrm{GeV}/{c}^{2}l{M}_{{K}^{+(0)}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}l2\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

Experimental constraints on the possible J**PC quantum numbers of the X(3872)

Abstract: We examine possible J^PC quantum number assignments for the X(3872). Angular correlations between final state particles in X(3872) --> pi+pi- J/psi decays are used to rule out J^PC values of 0++ and 0-+. The shape of the pi+pi- mass distribution near its upper kinematic limit favors S-wave over P-wave as the relative orbital angular momentum between the final-state dipion and J/psi, which strongly disfavors 1-+ and 2-+ assignments. The accumulated evidence strongly favors a J^PC = 1++ assignment for the X(3872), although the 2++ possibility is not ruled out by tests reported here. The analysis is based on a sample of X(3872) mesons produced via the exclusive process B --> K X(3872) in a 256 fb-1 data sample collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider.

Evidence for X(3872) ---> gamma J / psi and the sub-threshold decay X(3872) ---> omega J / psi

Abstract: We report evidence for the decay modes X(3872) --> gamma J/psi and X(3872)--> pi+pi-pi0 J/psip. In the latter, the pi+pi-pi0 invariant mass distribution has a strong peak between 750 MeV and the kinematic limit of 775 MeV, suggesting that the process is dominated by the sub-threshold decay X --> omega J/psi. These results establish the charge-conjugation parity of the X(3872) as C=+1. The results are based on a study of X(3872) mesons produced via exclusive B --> K X(3872) decays in a 256 fb-1 data sample collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The X(3872) --> gamma J/psi signal and the pi+pi-pi0 J/psi signal each has a statistical significance that is greater than 4 sigma.

Dalitz analysis of the three-body charmless decay B0 ---> K0(S) pi+ pi-

Abstract: We report preliminary results of a Dalitz plot analysis of three-body charmless B0=>Kspi+pi- decays. The analysis is performed with a data sample that contains 386 million $B\bar{B}$ pairs collected near the Y(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. Measurements of branching fractions for quasi-two-body decays B0=>rho(770)0K0, B0=>f0(980)K0, B0=>K*(892)+pi-, B0=>K*(1430)+pi-, and upper limits on several other quasi-two-body decay modes are reported.