We study the processes ee− 2!K+K−?+?-?, K+K−?°?°?, and K+K−K+K−?, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb−1 of BABAR data. The invariant mass of the hadronic final state defines the e+e− center-of-mass energy, so that the K+K−?+?−? data can be compared with direct measurements of the e+e− 2!K+K−?+?− reaction. No direct measurements exist for the e+e− 2!K+K−?°?° or e+e− 2!K+K−K+K− reactions, and we present an update of our previous result with doubled statistics. Studying the structure of these events, we find contributions from a number of intermediate states, and extract their cross sections. In particular, we perform a more detailed study of the e+e− 2!?(1020)??? reaction, and confirm the presence of the Y (2175) resonance in the?(1020)f0(980) and K+K− f0(980) modes. In the charmonium region, we observe the J/? in all three final states and in several intermediate states, as well as the?(2S) in some modes, and measure the corresponding branching fractions.

This paper reports measurements of processes: ee− →?K°{sub s}K{sup {+-}}?{sup {+-}}, e+e− →?K+K−?°, e+e− →??? and e+e− →???°. The initial state radiated photon allows to cover the hadronic final state in the energy range from thresholds up to ≈ 4.6 GeV. The overall size of the data sample analyzed is 232 fb−1, collected by the BABAR detector running at the PEP-II e+e− storage ring. From the Dalitz plot analysis of the K°{sub s}K{sup {+-}}?{sup {+-}} final state, moduli and relative phase of the isoscalar and the isovector components of the e+e− → KK*(892) cross section are determined. Parameters of? and? recurrences are also measured, using a global fitting procedure which exploits the interconnection among amplitudes, moduli and phases of the e+e− →K°{sub s}K{sup {+-}}?{sup {+-}}, K+K−?°,?? final states. The cross section for the OZI-forbidden process e+e− →??° and the J/? branching fractions to KK*(892) and K+K−? are also measured.

First results of a study of the ee− → ?+?−?+?−? process with hard photon emitted from initial state are presented. About 60000 fully reconstructed events have been selected based on 89.3 fb−1 of BABAR data. The invariant mass of the hadronic final state defines the effective collision c.m. energy, and so BABAR ISR data can be compared to the relevant direct e+e− measurements. From obtained 4? mass spectrum we evaluate e+e− → ?+?−?+?− cross section for the range of c.m.s. energy from 0.6 to 4.5 GeV. The systematic error of the cross section measurement is 5% and comparable with the best e+e− data. The cross sections for identified 2K2? and 4K final states also have been presented.

We study the processes e+e− → K+K−?+?−?, K+K−?°?°? and K+K−K+K−?, where the photon is radiated from the initial state. About 34600, 4400 and 2300 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 K+K−?+?−? data can be compared with direct measurements of the e+e− → K+K−?+?−? reaction; no direct measurements exist for the e+e− → K+K−?°?°? or e+e− → 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− → ?(1020)f0(980) and study its structure near threshold. In the charmonium region, we observe the J/? in all three final states and several intermediate states, as well as the ?/(2S) in some modes, and measure the corresponding branching fractions. We see no signal for the Y(4260) and obtain an upper limit of ?{sub Y(4260)→??+?−} · ?{sub ee}{sup Y}

We study the process ee− 2!?+?−?+?−?, 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 e+e− center-of-mass energy, so that these data can be compared with the corresponding direct e+e− measurements. From the 4?-mass spectrum, the cross section for the process e+e− 2!?+?−?+?− is measured for center-of-mass energies from 0.6 to 4.5 GeV. The uncertainty in the cross section measurement is typically 5%. We also measure the cross sections for the final states K+K−?+− and K+K−K+K−. We observe the J/? in all three final states and measure the corresponding branching fractions. We search for X(3872) in J/?(2!?+?−)?+?− and obtain an upper limit on the product of the e+e− width of the X(3872) and the branching fraction for X(3872) 2!J/??+?−.