Speaker
Summary
In proton-proton collisions at the LHC, pairs of top and anti-top quarks
are expected to be mostly produced through gluon fusion. Making use of the
large number of top quark pairs collected in the 7 TeV data, we present
measurements of the spin correlation between top and anti-top quarks
using several variables and discuss their sensitivity to new physics.
In addition, we present measurements of the top quark polarisation
predicted in models with CP-conserving and CP-violating processes. A top
pair-enriched sample of events with a single lepton (electron or muon),
missing transverse momentum and at least four high transverse momentum
jets, of which at least one is tagged as coming from a b-quark, is used to
measure tt production charge asymmetry to Ac=0.006 +/- 0.010.
Differential Ac measurements as a function of the invariant mass, the
rapidity and the transverse momentum of the tt-system are also presented.
In addition, Ac is measured for a subset of events with large tt velocity,
where physics beyond the Standard Model could contribute. All measurements
are consistent with the Standard Model predictions.
