Top quarks as a probe for heavy new physics

The heaviest fermion is expected to couple strongly to new physics and appears therefore as a natural probe in many BSM scenarios. Moreover, top physics has now entered in a precision era thanks to the huge amount of top quarks produced at hadron colliders, advanced experimental methods and accurate theoretical predictions. In this talk, we will used effective field theory to search for heavy new physics in a model independent way. This method can also be used to quantify the room left for new physics if no deviation from the SM is found.Comment: To appear in the proceedings XXII. International Workshop on Deep Inelastic Scattering and Related Subjects (DIS 2014), 28 April - 2 May 2014, Warsaw, Polan

New physics in top decay

After a short introduction to effective field theories, most of their features are illustrated using the top decay. The effects of heavy new physics on the top decay are computed and the constraints on the coefficients of the dimension-six operators are derived from the available measurements.Comment: 5 pages, 3 figures, Proceedings for Top201

A theoretical determination of the eta-eta' mixing

The systematic large N_c limit within chiral perturbation provides an optimal eta-eta' mixing angle of about -27 degrees at leading order in p^2. In this frame, agreement with the data can be reached with higher order corrections of about 20%.Comment: 12 pages, 2 figures; reference to the two-mixing-angle scheme added, minor corrections; to appear in JHE

Experimental study of strain accumulation of silica sand in a cyclic triaxial test

The experimental and phenomenological investigation of the elasto-plastic long-term behaviour of soils under dynamic loading is important for the development of risk analysis tools and numerical accumulation models for settlement prediction. Soil parameters, test equipment and loading conditions have a significant influence on strain accumulation, therefore a parameterization of the silica sand and a description of the re-engineered cyclic triaxial test device are performed in this paper. Long term cyclic triaxial tests are performed on a silica sand to investigate the influence of the number of cycles, the initial void ratio, the mean pressure and packages of cycles on the accumulation of residual strains. Empirical formulations of existing strain accumulation models are validated with test results on dry test samples

Single top polarisation as a window to new physics

We discuss the effect of heavy new physics, parameterised in terms of four-fermion operators, in the polarisation of single top (anti-)quarks in the $t$-channel process at the LHC. It is found that for operators involving a right-handed top quark field the relative effect on the longitudinal polarisation is twice larger than the relative effect on the total cross section. This enhanced dependence on possible four-fermion contributions makes the polarisation measurements specially interesting, in particular at high momenta.Comment: LaTeX 10 pages. v2: comments and references added, journal versio