Constraints on the SMEFT#

We compare the constraints on \(C_{tu}^{(8)}\) and \(C_{tG}\) at 95% CL obtained from a binned analysis to those obtained from the unbinned ML model.

In the upper plots we make use of two features: the invariant mass \(m_{t \bar{t}}\) and rapidity \(y_{t \bar{t}}\) of the top quark pair. In the lower plots we use a single feature, \(m_{t \bar{t}}\).

Two sets of binnings are used:

  • Binning 1:

\[\begin{split}m_{t \bar{t}} \in [1.45, 2.5, \infty) \textrm{ TeV}, \\ y_{t \bar{t}} \in \pm [0,1.5,3.0]\end{split}\]
  • Binning 2:

\[\begin{split}m_{t \bar{t}} \in [1.45, 1.5, 1.55, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1,\\ 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, \infty) \textrm{ TeV}, \\ y_{t \bar{t}} \in \pm [0, 0.3, 0.6, 0.9, 1.2, 3.0]\end{split}\]

In the left plots, we obtain constraints by working to linear order \(O(\Lambda^{-2})\) in the EFT calculation. In the right plots we work to quadratic order \(O(\Lambda^{-4})\).

../_images/tt_parton_2x2.png

In general, we find an improvement in the constraints obtained using the unbinned ML model compared to the binned analysis, as well as good agreement between the ML model and exact calculation.