CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Measurement of the t(t)over-bar production cross section with an in situ calibration of b-jet identification efficiency. Phys. Rev. D, 83(7), 071102–8pp.
Abstract: A measurement of the top-quark pair-production cross section in p (p) over bar collisions at root s = 1.96 TeV using data corresponding to an integrated luminosity of 1.12 fb(-1) collected with the Collider Detector at Fermilab is presented. Decays of top-quark pairs into the final states ev + jets and μv+ jets are selected, and the cross section and the b-jet identification efficiency are determined using a new measurement technique which requires agreement between the measured cross sections with exactly one and with multiple identified b quarks from the top-quark decays. Assuming a top-quark mass of 175 GeV/c(2), a cross section of 8.5 +/- 0.6(stat) +/- 0.7(syst)pb is measured.
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Jung, M., Pich, A., & Tuzon, P. (2011). B(bar) -> X_s gamma rate and CP asymmetry within the aligned two-Higgs-doublet model. Phys. Rev. D, 83(7), 074011–8pp.
Abstract: In the two-Higgs-doublet model the alignment of the Yukawa matrices in flavor space guarantees the absence of flavor-changing neutral currents at tree level, while introducing new sources for CP violation parametrized in a very economical way [Antonio Pich and Paula Tuzon, Phys. Rev. D 80, 091702 (2009)]. This implies a potentially large influence in a number of processes, b -> s gamma being a prominent example where rather high experimental and theoretical precision meet. We analyze the CP rate asymmetry in this inclusive decay and determine the resulting constraints on the model parameters. We demonstrate the compatibility with previously obtained limits [Martin Jung, Antonio Pich, and Paula Tuzon, J. High Energy Phys. 11 (2010) 003]. Moreover, we extend the phenomenological analysis of the branching ratio, and examine the influence of resulting correlations on the like-sign dimuon charge asymmetry in B decays.
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Bodenstein, S., Bordes, J., Dominguez, C. A., Peñarrocha, J., & Schilcher, K. (2011). QCD sum rule determination of the charm-quark mass. Phys. Rev. D, 83(7), 074014–4pp.
Abstract: QCD sum rules involving mixed inverse moment integration kernels are used in order to determine the running charm-quark mass in the (MS) over bar scheme. Both the high and the low energy expansion of the vector current correlator are involved in this determination. The optimal integration kernel turns out to be of the form p(s) = 1 -(s(0)/s)(2), where s(0) is the onset of perturbative QCD. This kernel enhances the contribution of the well known narrow resonances, and reduces the impact of the data in the range s similar or equal to 20-25 GeV2. This feature leads to a substantial reduction in the sensitivity of the results to changes in s(0), as well as to a much reduced impact of the experimental uncertainties in the higher resonance region. The value obtained for the charm-quark mass in the (MS) over bar scheme at a scale of 3 GeV is (m) over bar (c)(3 GeV) = 987 +/- 9 MeV, where the error includes all sources of uncertainties added in quadrature.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurement of the mass and width of the D_s1 (2536)+ meson. Phys. Rev. D, 83(7), 072003–14pp.
Abstract: The decay width and mass of the D-s1(2536)(+) meson are measured via the decay channel D-s1(+) -> (D*+KS0) using 385 fb(-1) of data recorded with the BABAR detector in the vicinity of the Gamma(4S) resonance at the PEP-II asymmetric-energy electron-positron collider. The result for the decay width is Gamma(D-s1(+)) = 92 +/- 0.03(stat.) +/- 0.04(syst.) MeV. For the mass, a value of m(D-s1(+)) = 2535.08 +/- 0.01(stat.) +/- 0.15(syst.) MeV/c(2) is obtained. The mass difference between the D-s1(+) and the D*+ is measured to be m(D-s1(+)) – m(D*+) = 524.83 +/- 0.01(stat.) +/- 0.04(syst.) MeV/c(2), representing a significant improvement compared to the current world average. The unnatural spin-parity assignment for the D-s1(+) meson is confirmed.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Search for CP violation in the decay D(+/-) --> K_S pi(+/-). Phys. Rev. D, 83(7), 071103–8pp.
Abstract: We report on a search for CP violation in the decay D-+/- -> K-S(0)pi(+/-) using a data set corresponding to an integrated luminosity of 469 fb(-1) collected with the BABAR detector at the PEP-II asymmetric energy e(+)e(-) storage rings. The CP- violating decay rate asymmetry A(CP) is determined to be (-0.44 +/- 0: 13(stat) +/- 0.10(syst))%, consistent with zero at 2.7 sigma and with the standard model prediction of (-0.332 +/- 0.006)%. This is currently the most precise measurement of this parameter.
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