126 research outputs found

    Measurements of the t(t)Overbar charge asymmetry using the dilepton decay channel in pp collisions at root s=7 TeV

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    The tt¯ charge asymmetry in proton-proton collisions at s√ = 7 TeV is measured using the dilepton decay channel (ee, e μ , or μμ ). The data correspond to a total integrated luminosity of 5.0 fb −1 , collected by the CMS experiment at the LHC. The tt and lepton charge asymmetries, defined as the differences in absolute values of the rapidities between the reconstructed top quarks and antiquarks and of the pseudorapidities between the positive and negative leptons, respectively, are measured to be A C = −0 . 010 ± 0 . 017 (stat . ) ± 0 . 008 (syst . ) and AlepC = 0 . 009 ± 0 . 010 (stat . ) ± 0 . 006 (syst . ). The lepton charge asymmetry is also measured as a function of the invariant mass, rapidity, and transverse momentum of the tt¯ system. All measurements are consistent with the expectations of the standard model

    Studies on crystal structure of inclusion chiral crystal of (R)-ethyl-2-pyridyl sulfoxide with (4R,5R)-TADDOL

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    The synthesis and crystal structure of 1 : 1 inclusion chiral crystal formed from (R)-ethyl-2-pyridyl sulfoxide with (4R, 5R)-alpha, alpha, alpha',alpha'-tetraalyl-1, 3-dioxolane-4, 5-dimethanol(TADDOL) were reported here. The crystal belongs to monoclinic, space group P2(1), a = 0.970 1(2) nm, b = 0.995 3(2) nm, c = 1.739 2(2) nm; beta = 92.079 degrees (14), V = 1.678 1(5) nm(3), M-r = 621.76, Z = 2, D-c = 1.230 g/cm(3). The final refinement converges to R = 0.053 1 and R-w2 = 0.077 2 for 2 335 observed independent reflections. Flack value is 0.1 (2). There is an intermolecular hydrogen bond in the inclusion crystal. Chiral TADDOL and ethyl-2-pyridyl sulfoxide(1) can be recognized each other in the inclusion crystal. Moreover, sulfoxide(1) in high enantiomeric excess was preparaed by resolution through inclusion complexation with the chiral TADDOL. The absolute configuration of (-)-ethyl-2-pyridyl sulfoxide was confirmed to be (R), which was assigned by the (R,R) absolute configuration of the TADDOL as an internal reference

    A study of cancer cell metastasis using microfluidic transmigration device

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    10.1109/MEMSYS.2012.6170300Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)773-776PMEM

    Determination of the number of J/ψ events with inclusive J/ψ decays

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    A measurement of the number of J/ψ events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be (223.7 ± 1.4) × 106, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/ψ events taken in 2012 is determined to be (1086.9 ± 6.0) × 106. In total, the number of J/ψ events collected with the BESIII detector is measured to be (1310.6 ± 7.0) × 106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible

    Measurements of the center-of-mass energies at BESIII via the di-muon process

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    From 2011 to 2014, the BESIII experiment collected about 5 fb-1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e+e- → γISR/FSRμ+μ-, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking

    Measurement of the absolute branching fraction for Λc+→Λμ+νμ

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    We report the first measurement of the absolute branching fraction for Λc+→Λμ+νμ. This measurement is based on a sample of e+e− annihilation data produced at a center-of-mass energy s=4.6 GeV, collected with the BESIII detector at the BEPCII storage rings. The sample corresponds to an integrated luminosity of 567 pb−1. The branching fraction is determined to be B(Λc+→Λμ+νμ)=(3.49±0.46(stat)±0.27(syst))%. In addition, we calculate the ratio B(Λc+→Λμ+νμ)/B(Λc+→Λe+νe) to be 0.96±0.16(stat)±0.04(syst)
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