We present measurements of the total production rates and momentum distributions of the charmed baryon $\Lambda_c^+$ in $e^+e^- \to$ hadrons at a center-of-mass energy of 10.54 GeV and in $\Upsilon(4S)$ decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in $e^+e^- \to c\bar{c}$ events, allowing direct studies of $c$-quark fragmentation. We measure a momentum distribution for $\Lambda_c^+$ baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of $\left< x_p \right> = 0.574\pm$0.009 and a total rate of $N_{\Lambda c}^{q\bar{q}} = 0.057\pm$0.002(exp.)$\pm$0.015(BF) $\Lambda_c^+$ per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, $pK^-\pi^+$. In $\Upsilon (4S)$ decays we measure a total rate of $N_{\Lambda c}^{\Upsilon} = 0.091\pm$0.006(exp.)$\pm$0.024(BF) per $\Upsilon(4S)$ decay, and find a much softer momentum distribution than expected from B decays into a $\Lambda_c^+$ plus an antinucleon and one to three pions.
LAMBDA/C+ differential production rate per hadronic event for the continuum at cm energy 10.54 GeV.
The integrated number of LAMBDA/C+'s per hadronic event for the continuum at cm energy 10.54 GeV.
LAMBDA/C+ differential production rate per UPSILON(4S) decay at cm energy 10.58 GeV.
We study the processes e+ e- --> 3(pi+pi-)gamma, 2(pi+pi-pi0)gamma and K+ K- 2(pi+pi-)gamma, with the photon radiated from the initial state. About 20,000, 33,000 and 4,000 fully reconstructed events, respectively, have been 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 these data can be compared with the corresponding direct e+e- measurements. From the 3(pi+pi-), 2(pi+pi-pi0) and K+ K- 2(pi+pi-) mass spectra, the cross sections for the processes e+ e- --> 3(pi+pi-), e+ e- --> 2(pi+pi-pi0) and e+ e- --> K+ K- 2(pi+pi-) are measured for center-of-mass energies from production threshold to 4.5 GeV. The uncertainty in the cross section measurement is typically 6-15%. We observe the J/psi in all these final states and measure the corresponding branching fractions.
The cross section for E+ E- --> 3PI+ 3PI- as measured with the ISR data. Errors are statistical only.
The cross section for E+ E- --> 2PI+ 2PI- 2PI0 as measured with the ISR data. Errors are statistical only.
The cross section for E+ E- --> K+ K- 2PI+ 2PI- as measured with the ISR data. Errors are statistical only.
The cross section of the process e+e−→π+π−π0 has been measured in the c.m. energy range 984–1060 MeV with the CMD-2 detector at the VEPP-2M collider. The obtained value of Br(ϕ→e+e−)Br(ϕ→π+π−π0)=(4.51±0.16±0.11)×10−5 is in good agreement with the previous measurements and has the best accuracy. Analysis of the Dalitz plot was performed. The contributions of the dominant ϕ→ρπ mechanism as well as of a small direct ϕ→3π amplitude were determined.
The Born cross section of the process e+e- -> pi+pi-pi0. The ranges of the c.m.s. energies are [2E-2*sigma, 2E+2*sigma], where sigma is statistical uncertainty of the VEPP-2M collider beam energy. The 2.5% systematic uncertainty of the cross section is fully correlated across the c.m.s. energy points.
We study the process $e^+e^-\to\pi^+\pi^-\pi^+\pi^-\gamma$, with a hard photon radiated from the initial state. About 60,000 fully reconstructed events have been selected from 89 $fb^{-1}$ of BaBar data. The invariant mass of the hadronic final state defines the effective \epem center-of-mass energy, so that these data can be compared with the corresponding direct $e^+e^-$ measurements. From the $4\pi$-mass spectrum, the cross section for the process $e^+e^-\to\pi^+\pi^-\pi^+\pi^-$ is measured for center-of-mass energies from 0.6 to 4.5 $GeV/c^2$. The uncertainty in the cross section measurement is typically 5%. We also measure the cross sections for the final states $K^+ K^- \pi^+\pi^-$ and $K^+ K^- K^+ K^-$. We observe the $J/\psi$ in all three final states and measure the corresponding branching fractions. We search for X(3872) in $J/\psi (\to\mu^+\mu^-) \pi^+\pi^-$ and obtain an upper limit on the product of the $e^+e^-$ width of the X(3872) and the branching fraction for $X(3872) \to J/\psi\pi^+\pi^-$.
Measured PI+ PI- PI+ PI- cross sections. The errors are statistical only.
Measured K+ K- PI+ PI- cross sections. The errors are statistical only.
Measured K+ K- K+ K- cross sections. The errors are statistical only.
The processes e+ e- --> eta gamma, e+ e- --> pi0 gamma --> 3 gamma have been studied in the c.m. energy range 600--1380 MeV with the CMD-2 detector. The following branching ratios have been determined: Br(rho --> eta gamma) = (3.21 +- 1.39 +- 0.20)x 10^{-4}; Br(omega --> eta gamma) = (4.44 + 2.29 -1.83 +- 0.28)x 10^{-4}; Br(phi --> eta gamma) = (1.373 +- 0.014 +- 0.085)x 10^{-2}; Br(rho --> pi0 gamma) = (6.21 +1.28 - 1.18 +- 0.39)x 10^{-4}; Br(omega --> pi0 gamma) = (9.06 +- 0.20 +- 0.57)x 10^{-2}; Br(phi --> pi0 gamma) = (1.258 +- 0.037 +- 0.077)x 10^{-3};
Born cross section for the process E+ E- --> ETA GAMMA.
Born cross section for the process E+ E- --> PI0 GAMMA.
The cross section of the process e+ e- --> omega pi0 --> pi0 pi0 gamma has been measured in the c.m. energy range 920-1380 MeV with the CMD-2 detector. Its energy dependence is well described by the interference of the rho(770) and rho'(1450) mesons decaying to omega pi0. Upper limits for the cross sections of the direct processes e+ e- --> pi0 pi0 gamma, eta pi0 gamma have been set.
Measurement of the Born cross section and the 'Bare' cross section of the process E+ E- --> OMEGA < PI0 GAMMA > PI0.
Upper limits for the non OMEGA PI0 cross section.
Upper limits of the ETA PI0 GAMMA cross section.
The process $e^+e^- \to K^0_L K^0_S$ has been studied with the CMD-2 detector using about 950 events detected in the center-of-mass energy range from 1.05 to 1.38 GeV. The cross section exceeds the expectation based on the contributions of the rho(770), omega(782) and phi(1020) mesons only.
Measured cross section and 'bare' cross section for the process E+ E- --> KL KS.
The cross section of the process e+ e- ---> eta gamma has been measured in the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following branching ratios have been determined: B(rho ---> eta gamma) = (3.28 +- 0.37 +- 0.23) 10^{-4}, B(omega ---> eta gamma) = (5.10 +- 0.72 +- 0.34) 10^{-4}, B(phi --> eta gamma) = (1.287 +- 0.013 +- 0.063) 10^{-2}. Evidence for the rho'(1450) ---> eta gamma decay has been obtained for the first time.
The measured Born cross section for the ETA GAMMA final state.
The process e+e- to pi+ pi- pi+ pi- pi0 has been studied in the center of mass energy range 1280 -- 1380 MeV using 3.0 1/pb of data collected with the CMD-2 detector in Novosibirsk. Analysis shows that the cross section of the five pion production is dominated by the contributions of the eta pi+pi- and omega pi+pi- intermediate states.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Using 11.6 pb^{-1} of data collected in the energy range 0.984--1.06 GeV by CMD-2 at VEPP-2M, the cross section of the reaction e+e- to pi+pi-pi+pi- has been studied. For the first time an interference pattern was observed in the energy dependence of the cross section near the phi meson. The branching ratio of the phi to pi+pi-pi+pi- decay double suppressed by the G-parity and OZI rule is measured Br(phi to pi+pi-pi+pi-) = (3.93 +- 1.74 +- 2.14) \cdot 10^{-6}. The upper limits have been placed for the decays phi to pi+pi-pi+pi-pi0 and phi to eta pi+pi- Br(phi to pi+pi-pi+pi-pi0) < 4.6 \cdot 10^{-6} 90% CL, Br(phi to eta pi+pi-) < 1.8 \cdot 10^{-5} 90% CL.
Only statistical errors are presented. The total systematic error is estimated to about 13 PCT.
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