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Register a new userThe B^- -> phi phi K^- decay rate with phi phi invariant mass below charm treshold
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Svjetlana Fajfer
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We investigate the decay mechanism in the B^- -> phi phi K^- decay with the phi phi invariant mass below the charm threshold and in the neighborhood of the eta_c invariant mass region. Our approach is based on the use of factorization model and the knowledge of matrix elements of the weak currents. For the B meson weak transition we apply form factor formalism, while for the light mesons we use effective weak and strong Lagrangians. We find that the dominant contributions to the branching ratio come from the eta, eta and eta(1490) pole terms of the penguin operators in the decay chains B^- -> eta (eta, eta(1490)) K^- -> phi phi K^-. Our prediction for the branching ratio is in agreement with the Belles result.
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Using a dataset corresponding to an integrated luminosity of 3.0 fb$^{-1}$ collected in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV, the $B_s^0 to phi phi$ branching fraction is measured to be [ mathcal{B}(B_s^0 to phi phi) = ( 1.84 pm 0.05 (text{stat}) pm 0.07 (text{syst}) pm 0.11 (f_s/f_d) pm 0.12 (text{norm}) ) times 10^{-5}, ] where $f_s/f_d$ represents the ratio of the $B_s^0$ to $B^0$ production cross-sections, and the $B^0 to phi K^*(892)^0$ decay mode is used for normalization. This is the most precise measurement of this branching fraction to date, representing a factor five reduction in the statistical uncertainty compared with the previous best measurement. A search for the decay $B^0 to phi phi$ is also made. No signal is observed, and an upper limit on the branching fraction is set as [ mathcal{B}(B^0 to phi phi) < 2.8 times 10^{-8} ] at 90% confidence level. This is a factor of seven improvement compared to the previous best limit.
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 energies 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 $B(eta_c(1S)tophiphi)/B(eta_c(1S)to pbar{p})=1.79pm0.14pm0.32$.
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.
The process e+e- ->pi+pi- has been studied with the SND detector at VEPP-2M e+e- collider in the vicinity of phi(1020) resonance. From the analysis of the energy dependence of measured cross section the branching ratio B(phi->pi+pi-)=(7.1+-1.1+-0.9)*10^{-5} and the phase psi_pi=-(34+-4+-3)degrees of interference with the non-resonant pi+pi- production amplitude were obtained.
We perform a theoretical study of the $chi_{cJ} to phi K^* bar K to phi Kpi bar K$ reaction taking into account the $K^* bar K$ final state interaction, which in the chiral unitary approach is responsible, together with its coupled channels, for the formation of the low lying axial vector mesons, in this case the $h_1(1380)$ given the selection of quantum numbers. Based on this picture we can easily explain why in the $chi_{c0}$ decay the $h_1(1380)$ resonance is not produced, and, in the case of $chi_{c1}$ and $chi_{c2}$ decay, why a dip in the $K^+ pi^0 K^-$ mass distribution appears in the 1550-1600 MeV region, that in our picture comes from a destructive interference between the tree level mechanism and the rescattering that generates the $h_1(1380)$ state. Such a dip is not reproduced in pictures where the nominal $h_1(1380)$ signal is added incoherently to a background, which provides support to the picture where the resonance appears from rescattering of vector-pseudoscalar components.
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