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تسجيل مستخدم جديدObservation of charmless baryonic decays $B^0_{(s)} to p overline{p} h^+ h^{prime-}$
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Decays of $B^0$ and $B_{s}^0$ mesons to the charmless baryonic final states $p overline{p} h^+ h^{prime-}$, where $h$ and $h^prime$ each denote a kaon or a pion, are searched for using the LHCb detector. The analysis is based on a sample of proton-proton collision data collected at center-of-mass energies of $7$ and $8,$TeV, corresponding to an integrated luminosity of $3,$fb$^{-1}$. Four-body charmless baryonic $B_{s}^0$ decays are observed for the first time. The decays $B^0_{s}to p overline{p} K^+ K^-$, $B^0_{s}to p overline{p} K^pm pi^mp$, $B^0to p overline{p} K^pm pi^mp$ and $B^0to p overline{p} pi^+pi^-$ are observed with a significance greater than $5$ standard deviations; evidence at $4.1$ standard deviations is found for the $B^0to p overline{p} K^+ K^-$ decay and an upper limit is set on the branching fraction for $B^0_{s}to p overline{p} pi^+ pi^-$. Branching fractions in the kinematic region $m(p overline{p})<2850,$MeV$/c^2$ are measured relative to the $B^0 to J/psi (to p overline{p}) K^*(892)^0$ channel.
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The first observation of the decays $B^0_{(s)} to J/psi p overline{p}$ is reported, using proton-proton collision data corresponding to an integrated luminosity of $5.2{text{,fb}}^{-1}$, collected with the mbox{LHCb}xspace detector. These decays are
suppressed due to limited available phase space, as well as due to Okubo-Zweig-Iizuka or Cabibbo suppression. The measured branching fractions are begin{align*} mathcal{B}(B^0 to J/psi p overline{p}) &= (4.51pm 0.40; text{(stat)} pm 0.44; text{(syst)}) times 10^{-7}, mathcal{B}(B^0_s to J/psi p overline{p}) &= (3.58pm 0.19; text{(stat)} pm 0.39; text{(syst)}) times 10^{-6}. end{align*} For the $B^0_s$ meson, the result is much higher than the expected value of $ {cal O} (10^{-9})$. The small available phase space in these decays also allows for the most precise single measurement of both the $B^0$ mass as ${5279.74 pm 0.30; ({rm stat})pm 0.10; ({rm syst})}$ MeV, and the $B^0_s$ mass as ${5366.85 pm 0.19; ({rm stat})pm 0.13; ({rm syst})}$ MeV.
The charmless three-body decays $B^0_{(s)} to K_{mathrm{scriptscriptstyle S}}^0 h^+ h^{prime -}$ (where $h^{(prime)} = pi, K$) are analysed using a sample of $pp$ collision data recorded by the LHCb experiment, corresponding to an integrated luminosi
ty of $3mbox{fb}^{-1}$. The branching fractions are measured relative to that of the $B^0 to K_{mathrm{scriptscriptstyle S}}^0 pi^{+} pi^{-}$ decay, and are determined to be: begin{eqnarray*} frac{{cal B}(B^0rightarrow K^0_{rm S}K^{pm}pi^{mp})}{{cal B}(B^0rightarrow K^0_{rm S}pi^{+}pi^{-})} = {} & 0.123 pm 0.009 ; mathrm{,(stat)}; pm 0.015 ; mathrm{,(syst)},, frac{{cal B}(B^0rightarrow K^0_{rm S}K^{+}K^{-})} {{cal B}(B^0rightarrow K^0_{rm S}pi^{+}pi^{-})} = {} & 0.549 pm 0.018 ; mathrm{,(stat)}; pm 0.033 ; mathrm{,(syst)},, frac{{cal B}(B_{s}^0rightarrow K^0_{rm S}pi^{+}pi^{-})}{{cal B}(B^0rightarrow K^0_{rm S}pi^{+}pi^{-})} = {} & 0.191 pm 0.027 ; mathrm{,(stat)}; pm 0.031 ; mathrm{,(syst)}; pm 0.011 ; (f_s/f_d) ,, frac{{cal B}(B_{s}^0rightarrow K^0_{rm S}K^{pm}pi^{mp})} {{cal B}(B^0rightarrow K^0_{rm S}pi^{+}pi^{-})} = {} & 1.70phantom{0} pm 0.07phantom{0} ; mathrm{,(stat)} ; pm 0.11phantom{0} ; mathrm{,(syst)}; pm 0.10phantom{0} ; (f_s/f_d) ,, frac{{cal B}(B_{s}^0rightarrow K^0_{rm S}K^{+}K^{-})}{{cal B}(B^0rightarrow K^0_{rm S}pi^{+}pi^{-})} in {} & [0.008 - 0.051] rm ~at~90%~confidence~level, end{eqnarray*} where $f_s/f_d$ represents the ratio of hadronisation fractions of the $B^0_s$ and $B^0$ mesons.
The results of searches for $B^{0}_{(s)} rightarrow J/{psi} p overline{p}$ and $B^{+} to J/{psi} p overline{p} {pi}^{+}$ decays are reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of $pp$ c
ollisions, collected with the LHCb detector. An excess with 2.8$,sigma$ significance is seen for the decay $B^{0}_{s} to J/{psi} p overline{p}$ and an upper limit on the branching fraction is set at the 90 % confidence level: ${cal B}(B^{0}_{s} to J/{psi} p overline{p}) < 4.8 times 10^{-6}$, which is the first such limit. No significant signals are seen for $B^{0} to J/{psi} p overline{p}$ and $B^{+} to J/{psi} p overline{p} {pi}^{+}$ decays, for which the corresponding limits are set: ${cal{B}}(B^{0} to J/{psi} p overline{p}) < 5.2 times 10^{-7}$, which significantly improves the existing limit; and ${cal{B}}(B^{+} to J/{psi} p overline{p} {pi}^{+}) < 5.0 times 10^{-7}$, which is the first limit on this branching fraction.
A search for previously unobserved decays of beauty baryons to the final states $K^0_{rmscriptscriptstyle S} p pi^{-}$ and $K^0_{rmscriptscriptstyle S}p K^{-}$ is reported. The analysis is based on a data sample corresponding to an integrated luminos
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