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We present a measurement of the correlation between the spins of t and tbar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb$^{-1}$. The measured value of the correlation coefficient in the off-diagonal basis, $O_{off} = 0.89 \pm 0.22$ (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.
"The first measurement of the differential cross section of the associated production of a photon and a bottom quark in proton-proton collisions is presented. Protons are accelerated and brought into collision at a center-of-mass energy of 8 TeV by the Large Hadron Collider. The collisions are recorded with the ATLAS detector and correspond to an integrated luminosity of up to 20.2 fb-1. The measurement is performed in two regions of the absolute value of the photon pseudorapidity: from 0 to 1.37 and from 1.56 to 2.37. The measurement is performed as a function of the photon transverse energy, from 25 to 400 GeV in the former pseudorapidity region and from 25 to 350 GeV in the latter region. The relative uncertainty in the measurement varies between 13% and 54% and is dominated by the uncertainty in the efficiency of identifying jets containing bottom quarks. The ratio of the cross section in the two pseudorapidity regions is also measured to reduce the positively correlated systematic uncertainties in the measurement between the two regions. The measurement is compared to predictions of perturbative quantum chromodynamics at the leading order and at the next-to-leading order. At low transverse energy, a good agreement is observed between the measured and the predicted values. At high transverse energy, however, the measured values are observed to be up to a factor of two larger than the most precise predicted values. This measurement can help improve the modelling of bottom quarks in perturbative quantum chromodynamics." --