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Register a new userDirect measurement of the phi(1020) leptonic branching ratio
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The process e+e-->mu+mu- has been studied by SND detector at VEPP-2M e+e- collider in the phi(1020)-resonance energy region. The measured effective phi meson leptonic branching ratio: B(phi->l+l-)=sqrt{B(phi->e+e-)*B(phi->mu+mu-)}=(2.89+-0.10+-0.06)*10^{-4} agrees well with the PDG value B(phi->e+e-)=(2.91+-0.07)*10^{-4} confirming mu-e universality. Without additional assumption of mu-e universality the branching ratio B(phi->mu+mu-)=(2.87+-0.20+-0.14)*10^{-4} was obtained.
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The $phi$(1020) meson leptonic width has been determined from the combined analysis of 4 major decay modes of the resonance ($phito K^+ K^-,K^0_LK^0_S,pi^+pi^-pi^0,etagamma$) studied with the CMD-2 detector at the VEPP-2M $e^+e^-$ collider. The following value has been obtained: $Gamma(phito e^+e^-) = 1.235pm 0.006pm 0.022$ keV. The $phi(1020)$ meson parameters in four main decay channels have been also recalculated: $B(phito K^+K^-) = 0.493pm 0.003pm 0.007$, $B(phito K_LK_S) = 0.336pm 0.002pm 0.006$, $B(phitopi^+pi^-pi^0) = 0.155pm 0.002pm 0.005$, $B(phitoetagamma) = 0.0138pm 0.0002pm 0.0002$.
We present the measurement of the $phi$(1020)$rightarrow e^{+}e^{-}$ transverse momentum spectrum and yield for $0.3 < p_{T} < 2.5$ GeV at mid-rapidity ($|y| < 1$) from the STAR experiment in Au+Au collisions at $sqrt{s_{_{NN}}} = 200$ GeV and compare it to the yield and spectrum from the hadronic decays. We also compare the $phi$(1020) mass and width obtained by fitting Breit-Wigner function to simulated values. Particle identification based on the newly installed STAR Time-Of-Flight (TOF) detector in conjunction with energy-loss (dE/dx) based particle identification measurements from the Time Projection Chamber (TPC) are used for a clean electron and positron identification.
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08 ^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical, the second systematic and the third is associated to the ratio of fragmentation fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/- 0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be (3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.
The branching fraction for the decay $K^{-} to pi^{0} e bar u$ is measured using in-flight decays detected with {bf ISTRA+} setup working at the 25 GeV negative secondary beam of the U-70 PS:linebreak $Br_{K_{e3}}= (5.124 pm 0.009 (stat) pm 0.029(norm) pm 0.030(syst))%$. From this value the $|V_{us}|$ element of the CKM matrix is extracted, using previously measured $f_{+}(t)$ form factor: $|V_{us}|=0.227 pm 0.002$. The results are in agreement with recent measurements by BNL E865, FNAL KTeV, KLOE.
The reaction e^+e^- ---> OMEGA+PI0 ---> PI+PI- 2PI0 has been studied with SND detector at VEPP-2M e^+e^- collider in the vicinity of the PHI(1020) meson resonance. The observed interference pattern in the energy dependence of the cross section is consistent with existence of the decay PHI ---> OMEGA+PI0 with a branching ratio of B(PHI ---> OMEGA+PI0)=(4.8+1.9-1.7+-0.8)x10^{-5}. The real and imaginary parts of the decay amplitude were measured. The PHI ---> OMEGA+PI0 decay was observed for the first time.
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