92 research outputs found

    Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

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    The B0B^0-Bˉ0\bar B^0 oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives Δmd=0.493±0.012(stat)±0.009(syst)\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)} ps1^{-1}.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

    Measurement of the CP-Violating Asymmetry Amplitude sin2β\beta

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    We present results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 million Y(4S) --> B Bbar decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B0 or B0bar from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta = 0.741 +/- 0.067 (stat) +/- 0.033 (syst) and |lambda| = 0.948 +/- 0.051 (stat) +/- 0.017 (syst). The magnitude of lambda is consistent with unity, in agreement with the Standard Model expectation of no direct CP violation in these modes

    Measurement of the electron energy spectrum and its moments in inclusive B -> Xe nu decays

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    We report a measurement of the inclusive electron energy spectrum for semileptonic decays of B mesons in a data sample of 52 million Y(4S)-->B(B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine the branching fraction, first, second, and third moments of the spectrum for lower cutoffs on the electron energy between 0.6 and 1.5 GeV. We measure the partial branching fraction to be B(B-->Xenu,E-e>0.6 GeV)=[10.36+/-0.06(stat.)+/-0.23(sys.)]%

    The Physics of the B Factories

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    Femoral neck narrowing following hip resurfacing using posterior and Ganz approaches at two years

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    We report a retrospective review of femoral head/neck ratios on post-operative and two year follow-up radiographs following hip resurfacing arthroplasty. The patients were in two matched groups, having had surgery through a posterior approach or via a Ganz trochanteric flip. There was no significant difference in femoral neck narrowing at follow up between the two surgical approaches. However, we found significant narrowing of the femoral neck in both groups by the time of the two year follow-up radiograph

    Inverted femoral head graft versus standard core decompression in nontraumatic hip osteonecrosis at minimum 3 years follow-up

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    Purpose Numerous salvage surgeries were popularised to halt the progression of hip osteonecrosis (ON). We aimed to compare the clinico-radiological outcomes of inverted femoral head graft (IFHG) versus standard core decompression (SCD) in treatment of nontraumatic hip ON at pre-arthritic stage. Methods A case review was performed at a minimum 3 years follow-up of 61 patients (71 hips; mean age 32.96 (19-50) years; mean follow-up 7.86 (3-14) years; mean body mass index 28.58 (19-46); 32 males, 29 females) suffering nontraumatic hip ON at pre-arthritic stage. 38 hips underwent SCD and 33 IFHG. The outcome was assessed by changes in modified Harris Hip Score (MHHS), need for revision surgery and progression of modified Ficat-Arlet staging. Data were analysed including logistic regression and Kaplan-Meier survivorship analysis. Results 13/34 (38.2%) hips in SCD group were revised at 4.61 ± 2.61 years, while 7/33 (21.2%) in IFHG group at 8.43 ± 4.32 years (p = 0.023). MHHS was significantly higher in IFHG group at 1 and 3 years as well as at last follow-up (p = 0.014, 0.001 and 0.023 respectively). Clinical and radiological significant differences were found in survivorship analysis between both groups, in favor of IFHG. A higher clinical failure was noted among obese patients. Conclusions An IFHG technique offers a better alternative regarding postoperative clinico-radiological outcomes in nontraumatic hip ON at the pre-arthritic stage. A cautious prognosis is recommended in obese patients
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