Probing CP Violation in h→τ^{-}τ^{+} at the LHC.

We propose a novel method to reconstruct event by event the full kinematics of the cascade decay process, h→τ^{+}τ^{-}→(π^{+}ν[over ¯])(π^{-}ν), which allows us to measure the τ^{+}τ^{-} spin correlation, a measure of the CP property of the Higgs boson. By noting that the τ^{±} momenta lie on the plane spanned by the accurately measured impact parameter and momentum vectors of charged pions, we can obtain the most likely momenta of the two missing neutrinos by using the probability distribution functions of the p[over →]_{T} vector and the location of the primary vertex. A simple detector level simulation shows an excellent agreement between the reconstructed and the true kinematics, both in the τ^{+}τ^{-} and the π^{+}π^{-} rest frames.

T-odd asymmetry in W + jet events at the LHC.

W bosons produced at high transverse momentum in hadron collisions can have polarization along the direction perpendicular to the production plane, which is odd under naïve T reversal where both the three-momenta and angular momenta are reversed. Perturbative QCD predicts nonzero polarization at the one-loop level, which can be measured as parity-odd components in the angular distribution of charged leptons from the decay of W bosons. We perform a detector-level simulation with the generator MadGraph5_aMC@NLO, and demonstrate that the asymmetry can be observed at the 8 TeV LHC with 20 fb(-1) of data.

Parity-odd asymmetries in W-jet events at the fermilab tevatron.

Parity-odd asymmetries in the decay angular distribution of a W boson produced with a hard jet in pp[over ] collisions arise only from QCD rescattering effects. If observed, these asymmetries will provide a first demonstration that perturbative QCD calculation is valid for the absorptive part of scattering amplitudes. We propose a simple observable to measure these asymmetries and perform realistic Monte Carlo simulations at energies reached at the Fermilab Tevatron.