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Register a new userFirst observation of a baryonic $B_s^0$ decay
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We report the first observation of a baryonic $B_s^0$ decay, $B_s^0 to p kern 0.1emoverline{kern -0.1emLambda} K^-$, using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3.0,mathrm{fb}^{-1}$. The branching fraction is measured to be $ mathcal{B}(B_s^0 to p kern 0.1emoverline{kern -0.1emLambda} K^-) + mathcal{B}(B_s^0 to bar{p} Lambda K^+) = left[5.46 pm 0.61 pm 0.57 pm 0.50 (mathcal{B}) pm 0.32 (f_s/f_d)right]times 10^{-6}, $ where the first uncertainty is statistical and the second systematic, the third uncertainty accounts for the experimental uncertainty on the branching fraction of the $B^0 to p kern 0.1emoverline{kern -0.1emLambda} pi^-$ decay used for normalization, and the fourth uncertainty relates to the knowledge of the ratio of $b$-quark hadronization probabilities $f_s/f_d$.
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The first observation of the decay $B_s^0 rightarrow phi bar{K}^{*0}$ is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of $pp$ collisions at $sqrt{s} = 7 TeV$, collected with the LHCb detector. A yield of $30 pm 6$ $B_s^0 rightarrow (K^+K^-)(K^-pi^+)$ decays is found in the mass windows $1012.5 < M(K^+K^-) < 1026.5 MeV/c^2$ and $746 < M(K^-pi^+)< 1046 MeV/c^2$. The signal yield is found to be dominated by $B_s^0 rightarrow phi bar{K}^{*0}$ decays, and the corresponding branching fraction is measured to be ${cal B}(B_s^0 rightarrow phi bar{K}^{*0}) = (1.10 pm 0.24 (stat) pm 0.14 (syst) pm 0.08 (f_d/f_s)) times 10^{-6}$, where the uncertainties are statistical, systematic and from the ratio of fragmentation fractions $f_d/f_s$ which accounts for the different production rate of $B^0$ and $B_s^0$ mesons. The significance of $B_s^0 rightarrow phi bar{K}^{*0}$ signal is 6.1 standard deviations. The fraction of longitudinal polarization in $B_s^0 rightarrow phi bar{K}^{*0}$ decays is found to be $f_0 = 0.51 pm 0.15 (stat) pm 0.07 (syst)$.
A baryonic decay of the $B_c^+$ meson, $B_c^+to J/psi poverline{p}pi^+$, is observed for the first time, with a significance of $7.3$ standard deviations, in $pp$ collision data collected with the LHCb detector and corresponding to an integrated luminosity of $3.0$ fb$^{-1}$ taken at center-of-mass energies of $7$ and $8$ $mathrm{TeV}$. With the $B_c^+to J/psi pi^+$ decay as normalization channel, the ratio of branching fractions is measured to be begin{equation*} frac{mathcal{B}(B_c^+to J/psi poverline{p}pi^+)}{mathcal{B}(B_c^+to J/psi pi^+)} = 0.143^{,+,0.039}_{,-,0.034},(mathrm{stat})pm0.013,(mathrm{syst}). end{equation*} The mass of the $B_c^+$ meson is determined as $M(B_c^+)=6274.0pm1.8,(mathrm{stat})pm0.4,(mathrm{syst}),mathrm{MeV}/c^2$, using the $B_c^+to J/psi poverline{p}pi^+$ channel.
The first observation of the decay of a $B^0$ meson to a purely baryonic final state, $B^0 to p bar{p}$, is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0 fb$^{-1}$. The branching fraction is determined to be $${cal B}(B^0 to p bar{p}) = ( 1.25 pm 0.27 pm 0.18 ) times 10^{-8} ,$$ where the first uncertainty is statistical and the second systematic. The decay mode $B^0 to p bar{p}$ is the rarest decay of the $B^0$ meson observed to date. The decay $B_s^0 to p bar{p}$ is also investigated. No signal is seen and the upper limit ${cal B}(B_s^0 to p bar{p}) < 1.5 times 10^{-8}$ at 90% confidence level is set on the branching fraction.
The first observation of the $B_s^0 to overline{D}^0 K^+ K^-$ decay is reported, together with the most precise branching fraction measurement of the mode $B^0 to overline{D}^0 K^+ K^-$. The results are obtained from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3.0~textrm{fb}^{-1}$. The data were collected with the LHCb detector at centre-of-mass energies of $7$ and $8$ TeV. The branching fraction of the $B^0 to overline{D}^0 K^+ K^-$ decay is measured relative to that of the decay $B^0 to overline{D}^0 pi^+ pi^-$ to be $$frac{mathcal{B}(B^0 to overline{D}^0 K^+ K^-)}{mathcal{B}(B^0 to overline{D}^0 pi^+ pi^-)} = (6.9 pm 0.4 pm 0.3)%,$$ where the first uncertainty is statistical and the second is systematic. The measured branching fraction of the $B_s^0 to overline{D}^0 K^+ K^-$ decay mode relative to that of the corresponding $B^0$ decay is $$frac{mathcal{B}(B_s^0 to overline{D}^0 K^+ K^-)}{mathcal{B}(B^0 to overline{D}^0 K^+ K^-)} = (93.0 pm 8.9 pm 6.9)%.$$ Using the known branching fraction of ${B^0 to overline{D}^0 pi^+ pi^-}$, the values of ${{mathcal B}(B^0 to overline{D}^0 K^+ K^- )=(6.1 pm 0.4 pm 0.3 pm 0.3) times 10^{-5}}$, and ${{cal B}(B_s^0 to overline{D}^0 K^+ K^-)=}$ $(5.7 pm 0.5 pm 0.4 pm 0.5) times 10^{-5}$ are obtained, where the third uncertainties arise from the branching fraction of the decay modes ${B^0 to overline{D}^0 pi^+ pi^-}$ and $B^0 to overline{D}^0 K^+ K^-$, respectively.
We measure the decay $B_s^0rightarrow K^0overline{K}^0$ using data collected at the $Upsilon(5S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. The data sample used corresponds to an integrated luminosity of 121.4 ${rm fb^{-1}}$. We measure a branching fraction $mathcal{B}(B_s^0rightarrow K^0overline{K}^0) = [19.6,^{+5.8}_{-5.1}({rm stat.}),pm1.0({rm sys.}),pm 2.0(N^{}_{B_s^0overline{B}_s^0})]times 10^{-6}$ with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.
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