4 research outputs found
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Observation of the Baryonic B decay B0bar to Lambda_c^+ anti-Lambda K-
The authors report the observation of the baryonic B decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +} {bar {Lambda}}K{sup -} with a significance larger than 7 standard deviations based on 471 x 10{sup 6} B{bar B} pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. They measure the branching fraction for the decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +} {bar {Lambda}}K{sup -} to be (3.8 {+-} 0.8{sub stat} {+-} 0.2{sub sys} {+-} 1.0 {sub {Lambda}{sub c}{sup +}}) x 10{sup -5}. The uncertainties are statistical, systematic, and due to the uncertainty in the {Lambda}{sub c}{sup +} branching fraction. They find that the {Lambda}{sub c}{sup +} K{sup -} invariant mass distribution shows an enhancement above 3.5 GeV/c{sup 2}
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Measurement of the Mass and Width of the Ds1(2536)+ Meson
The decay width and mass of the D{sub s1}(2536){sup +} meson are measured via the decay channel D{sub s1}{sup +} {yields} D*{sup +} K{sub S}{sup 0} using 385 fb{sup -1} of data recorded with the BABAR detector in the vicinity of the {Upsilon}(4S) resonance at the PEP-II asymmetric-energy electron-positron collider. The result for the decay width is {Gamma}(D{sub s1}{sup +}) = 0.92 {+-} 0.03 (stat.) {+-} 0.04 (syst.)MeV. For the mass, a value of m(D{sub s1}{sup +}) = 2535.08 {+-} 0.01 (stat.) {+-} 0.15 (syst.)MeV/c{sup 2} is obtained. The mass difference between the D{sub s1}{sup +} and the D*{sup +} is measured to be m(D{sub s1}{sup +})-m(D*{sup +}) = 524.83 {+-} 0.01 (stat.) {+-} 0.04 (syst.)MeV/c{sup 2}, representing a significant improvement compared to the current world average. The unnatural spin-parity assignment for the D{sub s1}{sup +} meson is confirmed
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Cross Sections for the Reactions e+e to K+ K- pi+pi-, K+ K- pi0pi0, and K+ K- K+ K- Measured Using Initial-State Radiation
We study the processes e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}-{gamma}, K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0}{gamma}, and K{sup +}K{sup -}K{sup +}K{sup -}{gamma}, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb{sup -1} of BABAR data. The invariant mass of the hadronic final state defines the e{sup +}e{sup -} center-of-mass energy, so that the K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{gamma} data can be compared with direct measurements of the e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}{sup -} reaction. No direct measurements exist for the e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0} or e{sup +}e{sup -} {yields} K{sup +}K{sup -}K{sup +}K{sup -} 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{sup +}e{sup -} {yields} {phi}(1020){pi}{pi}{gamma} reaction, and confirm the presence of the Y (2175) resonance in the {phi}(1020)f{sub 0}(980) and K{sup +}K{sup -} f{sub 0}(980) modes. In the charmonium region, we observe the J/{psi} in all three final states and in several intermediate states, as well as the {phi}(2S) in some modes, and measure the corresponding branching fractions