Top-quark charge asymmetry and polarization in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mi>t</mml:mi><mml:mover accent="true"><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">¯</mml:mo></mml:mrow></mml:mover><mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msup></mml:math>production at the LHC

We study the charge asymmetry between the t and t¯ quarks at the LHC, when they are produced in association with a W boson. Though sizably reducing the cross section with respect to the inclusive production, requiring a W boson in the final state has two important implications. First, at leading order in QCD, tt¯W± production can only occur via qq¯ annihilation. As a result, the asymmetry between the t and t¯ generated at NLO in QCD is significantly larger than that of inclusive tt¯ production, which is dominated by gluon fusion. Second, the top quarks tend to inherit the polarization of the initial-state quarks as induced by the W-boson emission. Hence, the decay products of the top quarks display a sizable asymmetry already at the leading order in QCD. We study the relevant distributions and their uncertainties in the standard model, compare them to those obtained in a simple axigluon model and discuss prospects for measurements at the LHC and beyond.

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