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تسجيل مستخدم جديدObservation of the $B_s^0 rightarrow J/psi phi phi$ decay
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The $B_s^0 rightarrow J/psi phi phi$ decay is observed in $pp$ collision data corresponding to an integrated luminosity of 3 fb$^{-1}$ recorded by the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV. This is the first observation of this decay channel, with a statistical significance of 15 standard deviations. The mass of the $B_s^0$ meson is measured to be $5367.08,pm ,0.38,pm, 0.15$ MeV/c$^2$. The branching fraction ratio $mathcal{B}(B_s^0 rightarrow J/psi phi phi)/mathcal{B}(B_s^0 rightarrow J/psi phi)$ is measured to be $0.0115,pm, 0.0012, ^{+0.0005}_{-0.0009}$. In both cases, the first uncertainty is statistical and the second is systematic. No evidence for non-resonant $B_s^0 rightarrow J/psi phi K^+ K^-$ or $B_s^0 rightarrow J/psi K^+ K^- K^+ K^-$ decays is found.
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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 dete
ctor. 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 $f_0 = 0.51 pm 0.15 (stat) pm 0.07 (syst)$.
Using a sample of $1.31$ billion $J/psi$ events accumulated with the BESIII detector at the BEPCII collider, we report the observation of the decay $J/psi rightarrow phipi^{0}$, which is the first evidence for a doubly Okubo-Zweig-Iizuka suppressed e
lectromagnetic $J/psi$ decay. A clear structure is observed in the $K^{+} K^{-}$ mass spectrum around 1.02 GeV/$c^2$, which can be attributed to interference between $J/psi rightarrow phipi^{0}$ and $J/psi rightarrow K^{+}K^{-}pi^{0}$ decays. Due to this interference, two possible solutions are found. The corresponding measured values of the branching fraction of $J/psi to phipi^{0}$ are $[2.94 pm 0.16text{(stat.)} pm 0.16text{(syst.)}] times 10^{-6}$ and $[1.24 pm 0.33text{(stat.)} pm 0.30text{(syst.)}] times 10^{-7}$.
A search for the rare decay $B^0 rightarrow J/psi phi$ is performed using $pp$ collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 ${rm fb}^{-1}$. No significan
t signal of the decay is observed and an upper limit of $1.1 times 10^{-7}$ at 90% confidence level is set on the branching fraction.
Using decays to $phi$-meson pairs, the inclusive production of charmonium states in $b$-hadron decays is studied with $pp$ collision data corresponding to an integrated luminosity of $3.0fb^{-1}$, collected by the LHCb experiment at centre-of-mass en
ergies of 7 and 8 TeV. Denoting by $B_Cequiv B(bto CX)times B(Ctophiphi)$ the inclusive branching fraction of a $b$ hadron to a charmonium state $C$ that decays into a pair of $phi$ mesons, ratios $R^{C1}_{C2}equiv B_{C1}/B_{C2}$ are determined as $R^{chi_{c0}}_{eta_c(1S)}=0.147pm0.023pm0.011$, $R^{chi_{c1}}_{eta_c (1S)}=0.073pm0.016pm0.006$, $R^{chi_{c2}}_{eta_c (1S)}=0.081pm0.013pm0.005$, $R^{chi_{c1}}_{chi_{c0}}=0.50pm0.11pm0.01$, $R^{chi_{c2}}_{chi_{c0}}=0.56pm0.10pm0.01$ and $R^{eta_c (2S)}_{eta_c(1S)}=0.040pm0.011pm0.004$. Here and below the first uncertainties are statistical and the second systematic. Upper limits at $90%$ confidence level for the inclusive production of $X(3872)$, $X(3915)$ and $chi_{c2}(2P)$ states are obtained as $R^{X(3872)}_{chi_{c1}}<0.34$, $R^{X(3915)}_{chi_{c0}}<0.12$ and $R^{chi_{c2}(2P)}_{chi_{c2}}<0.16$. Differential cross-sections as a function of transverse momentum are measured for the $eta_c(1S)$ and $chi_c$ states. The branching fraction of the decay $B_s^0rightarrowphiphiphi$ is measured for the first time, $B(B_s^0tophiphiphi)=(2.15pm0.54pm0.28pm0.21_{B})times 10^{-6}$. Here the third uncertainty is due to the branching fraction of the decay $B_s^0tophiphi$, which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse $phi$ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the $eta_c(1S)$ decays to $phiphi$ and $pbar{p}$ as $B(eta_c(1S)tophiphi)/B(eta_c(1S)to pbar{p})=1.79pm0.14pm0.32$.
A measurement of the relative branching fraction of $B_{s}^{0} rightarrow J/ps i f_{0}(980), f_{0}(980) rightarrow pi^{+}pi^{-}$ to $B_{s}^{0} rightarrow J/psi phi, p hi rightarrow K^{+}K^{-}$ is presented. The decay mode $B_{s}^{0} rightarrow J/psi
f_{0}(980)$ is an interesting mode since it is a CP-odd eigenstate which could be used in CP-violating studies. Using approximat ely 8 $rm{fb}^{-1}$ of data recorded with the D0 detector at the Fermilab Tevatron Collider, a relative branching fraction of 0.210 $pm$ 0.032thinspace(stat) $pm$ 0.036thi nspace(syst) is found.
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