Asymmetries in t(t)over-bar production: LHC versus Tevatron

The measurement of a charge asymmetry in t (t) over bar production at the LHC constitutes more than an independent confirmation of the forward-backward asymmetry found at the Tevatron. Indeed, both measurements together can be used to identify the source of the asymmetry. This is demonstrated for the case of new Z', W' vector bosons and color-sextet and triplet scalars, exchanged in t, u channels, respectively, and a very heavy axigluon in the s channel. In particular, current LHC measurements disfavor Z', W' models above the 2 sigma level.