BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Study of e(+)e(-) -> p(p)over-bar via initial-state radiation at BABAR. Phys. Rev. D, 87(9), 092005–18pp.
Abstract: The process e(+)e(-) -> p (p) over bar gamma is studied using 469 fb(-1) of integrated luminosity collected with the BABAR detector at the SLAC National Accelerator Laboratory, at an e(+)e(-) center-of-mass energy of 10.6 GeV. From the analysis of the p (p) over bar invariant mass spectrum, the energy dependence of the cross section for e(+)e(-) -> p (p) over bar is measured from threshold to 4.5 GeV. The energy dependence of the ratio of electric and magnetic form factors, vertical bar G(E)/G(M)vertical bar, and the asymmetry in the proton angular distribution are measured for p (p) over bar masses below 3 GeV. We also measure the branching fractions for the decays J/psi -> p (p) over bar and psi(2S) -> p (p) over bar are also determined.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Precision Measurement of the B -> Xs gamma Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry ACP(B -> Xs+d gamma). Phys. Rev. Lett., 109(19), 191801–8pp.
Abstract: The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B --> X-s gamma plus B --> X-d gamma, is studied using a data sample of (382.8 +/- 4.2) x 10(6)Y(4S) --> B (B) over bar decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B --> X-s gamma) = (3.21 +/- 0.33) x 10(-4) for E-gamma > 1.8 GeV and the direct CP asymmetry A(CP)(B --> Xs+d gamma) = 0.057 +/- 0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Measurement of B (B -> Xs gamma), the B -> Xs gamma photon energy spectrum, and the direct CP asymmetry in B -> Xs+d gamma decays. Phys. Rev. D, 86(11), 112008–33pp.
Abstract: The photon spectrum in B -> X-s gamma decay, where X-s is any strange hadronic state, is studied using a data sample of (382.8 +/- 4.2) x 10(6) e(+)e(-) -> Upsilon(4S) -> B (B) over bar events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction B(B -> X-s gamma) (3.21 +/- 0.15 +/- 0.29 +/- 0.08) x 10(-4) and the first, second, and third moments < E-gamma > = 2.267 +/- 0.019 +/- 0.032 +/- 0.003 GeV, <(E-gamma – < E-gamma >)(2)> = 0.0484 +/- 0.0053 +/- 0.0077 +/- 0.0005 GeV2, and <(E-gamma – < E-gamma)(3)> = -0.0048 +/- 0.0011 +/- 0.0011 +/- 0.0004 GeV3, for the range E-gamma > 1.8 GeV, where E-gamma is the photon energy in the B-meson rest frame. Results are also presented for narrower E-gamma ranges. In addition, the direct CP asymmetry A(CP)(B -> Xs+d gamma) is measured to be 0.057 +/- 0.063. The spectrum itself is also unfolded to the B-meson rest frame; that is the frame in which theoretical predictions for its shape are made.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Measurement of the e(+)e(-) -> p(p)over-bar cross section in the energy range from 3.0 to 6.5 GeV. Phys. Rev. D, 88(7), 072009–12pp.
Abstract: The e(+)e(-) -> p (p) over bar cross section and the proton magnetic form factor have been measured in the center-of-mass energy range from 3.0 to 6.5 GeV using the initial-state radiation technique with an undetected photon. This is the first measurement of the form factor at energies higher than 4.5 GeV. The analysis is based on 469 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider at e(+)e(-) center-of-mass energies near 10.6 GeV. The branching fractions for the decays J/psi -> p (p) over bar and psi(2S) -> p (p) over bar have also been measured.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2015). Study of the e(+)e(-) -> K+K- reaction in the energy range from 2.6 to 8.0 GeV. Phys. Rev. D, 92(7), 072008–16pp.
Abstract: The e(+)e(-) -> K+K- cross section and charged-kaon electromagnetic form factor are measured in the e(+)e(-) center-of-mass energy range (E) from 2.6 to 8.0 GeV using the initial-state radiation technique with an undetected photon. The study is performed using 469 fb(-1) of data collected with the BABAR detector at the PEP-II2 e(+)e(-) collider at center-of-mass energies near 10.6 GeV. The form factor is found to decrease with energy faster than 1/E-2 and approaches the asymptotic QCD prediction. Production of the K+K- final state through the J/psi and psi(2S) intermediate states is observed. The results for the kaon form factor are used together with data from other experiments to perform a model-independent determination of the relative phases between electromagnetic (single-photon) and strong amplitudes in J/psi and psi(2S). K+K- decays. The values of the branching fractions measured in the reaction e(+)e(-) -> K+K- are shifted relative to their true values due to interference between resonant and nonresonant amplitudes. The values of these shifts are determined to be about +/- 5% for the J/psi meson and +/- 15% for the psi(2S) meson.
|