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Register a new userNuclear-matter modification of decay widths in the $phi to e^{+}e^{-}$ and $phi to K^{+}K^{-}$ channels
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The invariant mass spectra of $phi to K^{+}K^{-}$ are measured in 12 GeV $p+A$ reactions in order to search for the in-medium modification of $phi$ mesons. The observed $K^{+}K^{-}$ spectra are well reproduced by the relativistic Breit-Wigner function with a combinatorial background shape in three $betagamma$ regions between 1.0 and 3.5. The nuclear mass-number dependence of the yields of the $K^{+}K^{-}$ decay channel is compared to the simultaneously measured $e^{+}e^{-}$ decay channel for carbon and copper targets. We parameterize the production yields as $sigma (A) = sigma_0 times A^alpha$ and obtain $alpha_{phito K^+K^-} - alpha_{phito e^+e^-}$ to be 0.14 $pm$ 0.12. Limits are obtained for the partial decay widths of $phi$ mesons in nuclear matter.
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The properties of the phi-meson have been measured via its e+e- and K+K- decay channels in Au+Au collisions at sqrt{s_NN} = 200 GeV by the PHENIX experiment. The preliminary yields and temperatures derived for the minimum bias and several centrality bins in both decay channels are presented.
We measure the Born cross sections of the process $e^{+}e^{-} to K^{+}K^{-}K^{+}K^{-}$ at center-of-mass (c.m.) energies, $sqrt{s}$, between 2.100 and 3.080 GeV. The data were collected using the BESIII detector at the BEPCII collider. An enhancement at $sqrt{s}= 2.232$ GeV is observed, very close to the $e^{+}e^{-} to Lambda overline{Lambda}$ production threshold. A similar enhancement at the same c.m. energy is observed in the $e^{+}e^{-} to phi K^{+}K^{-}$ cross section. The energy dependence of the $K^{+}K^{-}K^{+}K^{-}$ and $phi K^{+}K^{-}$ cross sections differs significantly from that of $e^{+}e^{-} to phi pi^{+}pi^{-}$.
Using a data sample of $448.1times10^6$ $psi(3686)$ events collected at $sqrt{s}=$ 3.686 GeV with the BESIII detector at the BEPCII, we search for the rare decay $J/psi to phi e^+ e^-$ via $psi(3686) to pi^+pi^- J/psi $. No signal events are observed and the upper limit on the branching fraction is set to be $mathcal{B}(J/psi to phi e^+ e^-) < 1.2 times 10^{-7}$ at the 90% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.
Using 2.92 fb$^{-1}$ of electron-positron annihilation data collected at a center-of-mass energy of $sqrt{s}= 3.773$ GeV with the BESIII detector, we present an improved measurement of the branching fraction $mathcal{B}(D^+ to omega e^+ u_{e}) = (1.63pm0.11pm0.08)times 10^{-3}$. The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time, we measure them to be $r_V = 1.24pm0.09pm0.06$ and $r_2 = 1.06pm0.15 pm 0.05$. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay $D^+ to phi e^+ u_{e}$. An improved upper limit $mathcal{B}(D^+ to phi e^+ u_{e}) < 1.3 times 10^{-5}$ is set at 90% confidence level.
The cross sections of the processes $e^+e^- to K^+K^-$, $e^+e^- to K_SK_L$ and $e^+e^- to pi^+pi^-pi^0$ were measured in the SND experiment at the VEPP-2M collider in the energy region near the $phi(1020)$ meson. These measurements were based on about $10^6$ $K^+K^-$, $0.5 times 10^6$ $K_SK_L$ and $0.4 times 10^6$ $pi^+pi^-pi^0$ selected events. Themeasured cross sections have been analyzed in the framework of the vector meson dominance model and the main parameters of the $phi$-resonance were obtained, such as its mass, width, the production cross section and branching ratios of the main decay modes. The measured value of the $phi$ meson total width, $Gamma_{phi} = 4.21 pm 0.04$ is lower than the present world average of $4.458 pm 0.032$ MeV. Contributions in addition to the conventional vector meson dominance model were found in the $e^+e^- to pi^+pi^-pi^0$ reaction cross section.
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