Using Top Quark Decay to Search for New Physics

Indianapolis, IN

In the early 21st century, the search for experimental verification for physics beyond the Standard Model (SM) has been mostly fruitless. As the Large Hadron Collider (LHC) is being prepared to explore higher energy ranges, physicists are hopeful that we will gain further insight into the structure of our universe. Most experimental evidence supports the SM, despite the fact that many have tried to find flaws. Examples of physics beyond the SM, or "new physics" (NP), would include interactions with new, heavy particles or processes occurring with different mediators that have been hypothesized to exist, but have not yet been discovered. Thus physicists must use particle accelerators like the LHC to look at high energies, far removed from the daily experience, to attempt to find evidence of NP. We consider NP contributions to the scattering g g -> t anti-t -> (b anti-b c) (anti-b l anti-nu_l). NP couplings are parameterized using an effective Lagrangian with 10 Lorentz structures, which are subsequently analyzed to find observables that differ from the SM contribution. This scattering is examined in a search for mediators that may not be predicted by the SM. To find the effects of such a mediator, we consider observables such as the cross section, sigma, and differential cross sections d(sigma)/dX and d(sigma)/dXdY, where X and Y represent various kinematical quantities. It is shown that careful measurements of the shapes of these differential distributions could allow experimentalists to distinguish the presence of NP and, to some extent, the nature of the NP contributions.