The discrete-time multifactor Vasiček model is a tractable Gaussian spot rate model. Typically, two- or three-factor versions allow one to capture the dependence structure between yields with different times to maturity in an appropriate way. In practice, re-calibration of the model to the...

We consider a one-parameter family of short rate models which encompasses both Hull-White (normal) and Black-Karasinski (lognormal) models. We deduce a general form for the relevant Green's function as an asymptotic series, assuming only that the deviations of the short rate from the forward...