Exploring Two-Field Inflation in the Wess-Zumino Model
  We explore inflation via the effective potential of the minimal Wess-Zumino
model, considering both the real and imaginary components of the complex field.
Using transport techniques, we calculate the full allowed range of $n_s$, $r$
and $f_{\rm NL}$ for different choices of the single free parameter, $v$, and
present the probability distribution of these signatures given a simple choice
for the prior distribution of initial conditions. Our work provides a case
study of multi-field inflation in a simple but realistic setting, with
important lessons that are likely to apply more generally. For example, we find
that there are initial conditions consistent with observations of $n_s$ and $r$
for values of $v$ that would be excluded if only evolutions in the real field
direction were to be considered, and that these may yield enhanced values of
$f_{\rm NL}$. Moreover, we find that initial conditions fixed at high energy
density, where the potential is close to quartic in form, can still lead to
evolutions in a concave region of the potential during the observable number of
e-folds, as preferred by present data. The Wess-Zumino model therefore provides
an illustration that multi-field dynamics must be taken into account when
seeking to understand fully the phenomenology of such models of inflation.
