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Register a new userMeasurements of the parameters of the $phi(1020)$ resonance through studies of the processes $e^+e^- to K^+K^-$, $K_SK_L$ and $pi^+pi^-pi^0$
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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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We study the processes $e^+ e^-to 2(pi^+pi^-)pi^0gamma$, $2(pi^+pi^-)etagamma$, $K^+ K^-pi^+pi^-pi^0gamma$ and $K^+ K^-pi^+pi^-etagamma$ with the hard photon radiated from the initial state. About 20000, 4300, 5500 and 375 fully reconstructed events, respectively, are selected from 232 fb$^{-1}$ of BaBar data. The invariant mass of the hadronic final state defines the effective $e^+ e^-$ center-of-mass energy, so that the obtained cross sections from the threshold to about 5 GeV can be compared with corresponding direct epem measurements, currently available only for the $etapi^+pi^-$ and $omegapi^+pi^-$ submodes of the $e^+ e^-to 2(pi^+pi^-)pi^0$ channel. Studying the structure of these events, we find contributions from a number of intermediate states, and we extract their cross sections where possible. In particular, we isolate the contribution from $e^+ e^-toomega(782)pi^+pi^-$ and study the $omega(1420)$ and $omega(1650)$ resonances. In the charmonium region, we observe the $J/psi$ in all these final states and several intermediate states, as well as the $psi(2S)$ in some modes, and we measure the corresponding branching fractions.
We report measurements of the observed cross sections for $e^+e^-toomega pi^+pi^-$, $omega K^+K^-$, $omega pbar p$, $K^+K^-rho^0pi^0$, $K^+K^-rho^+pi^-+c.c.$, $K^{*0}K^-pi^+pi^0+c.c.$, $K^{*+}K^-pi^+pi^-+c.c.$, $phipi^+pi^-pi^0$ and $Lambda bar Lambda pi^0$ at $sqrt s=$ 3.773 and 3.650 GeV. Upper limits (90% C.L.) are given for observed cross sections and for $psi(3770)$ decay branching fractions for production of these final states. These measurements are made by analyzing the data sets of 17.3 pb$^{-1}$ collected at $sqrt{s}=3.773$ GeV and 6.5 pb$^{-1}$ collected at $sqrt{s}=3.650$ GeV with the BES-II detector at the BEPC collider.
Using $e^{+}e^{-}$ collision data samples with center-of-mass energies ranging from 2.000 to 2.644 GeV, collected by the BESIII detector at the BEPCII collider, and with a total integrated luminosity of 300 pb^{-1}, a partial-wave analysis is performed for the process $e^{+}e^{-} to K^{+}K^{-}pi^{0}pi^{0}$. The total Born cross sections for the process $e^{+}e^{-} to K^{+}K^{-}pi^{0}pi^{0}$, as well as the Born cross sections f or the subprocesses $e^{+}e^{-} to phi pi^{0}pi^{0}$, $K^{+}(1460)K^{-}$, $K^{+}_{1}(1400)K^{-}$, $K^{+}_{1}(1270)K^{-}$ and $K^{*+}(892)K^{*-}(892)$, are measured versus the center-of-mass energy. The corresponding results for $e^{+}e^{-} to K^{+}K^{-}pi^{0}pi^{0}$ and $phi pi^{0}pi^{0}$ are consistent with those of BaBar and have much improved precision.By analyzing the cross sections for the four subprocesses, $K^{+}(1460)K^{-}$, $K^{+}_{1}(1400)K^{-}$, $K^{+ }_{1}(1270)K^{-}$ and $K^{*+}K^{*-}$, a structure with mass $M$ = (2126.5 $pm$ 16.8 $pm$ 12.4)~MeV/c^{2} and width $Gamma$ = (106.9 $pm$ 32.1 $pm$ 28.1)~MeV is observed with an overall statistical significance of 6.3 $sigma$, although with very limited significance in the subprocesses $e^{+}e^{-} to K^{+}_{1}(1270)K^{-}$ and $K^{*+}(892)K^{*-}(892)$. The resonant parameters of the observed structure suggest it can be identified with the $phi(2170)$, thus the results provide valuable input to the internal nature of the $phi(2170)$.
We study the processes $e^+ e^-to K^+ K^- pi^+pi^-gamma$, $K^+K^-pi^0pi^0gamma$ and $K^+ K^- K^+ K^-gamma$, where the photon is radiated from the initial state. About 34600, 4400 and 2300 fully reconstructed events, respectively, are selected from 232 invfb of babar data. The invariant mass of the hadronic final state defines the effective epem center-of-mass energy, so that the $K^+ K^- pi^+pi^-gamma$ data can be compared with direct measurements of the $e^+ e^-to K^+K^- pipi$ reaction; no direct measurements exist for the $e^+ e^-to K^+ K^- pi^0pi^0$ or $epemto K^+ K^- K^+ K^-$ reactions. Studying the structure of these events, we find contributions from a number of intermediate states, and we extract their cross sections where possible. In particular, we isolate the contribution from $e^+ e^-tophi(1020) f_{0}(980)$ and study its structure near threshold. In the charmonium region, we observe the $J/psi$ in all three final states and several intermediate states, as well as the $psi(2S)$ in some modes, and measure the corresponding branching fractions. We see no signal for the Y(4260) and obtain an upper limit of $BR_{Y(4260)tophipi^+pi^-}cdotGamma^{Y}_{ee}<0.4 ev$ at 90% C.L.
The $e^+e^- to omega pi^0 to pi^0 pi^0 gamma$ process was investigated in the SND experiment at the VEPP-2M collider. A narrow energy interval near the $phi$-meson was scanned. The observed cross-section reveals, at the level of three standard deviation, the interference effect caused by $phi to pi^0pi^0gamma$ decay. The cross-section parameters, as well as the real and imaginary parts of the $phi$-meson related amplitude, were measured.
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