A General Characterization of Quadratic Term Structure Models

In this paper, we define a strongly regular quadratic Gaussian process to characterize quadratic term structure models (QTSMs) in a general Markov setting. The key of this definition is to keep the analytical tractability of QTSMs which has the quadratic term structure of the yield curve. In order to keep this property, under the regularity condition, we have proven that no jumps are allowed in the infinitesimal generator of the underlying state process. The coefficient functions defined in the quadratic Gaussian relationship can be decided by the multi-variate Riccati Equations with a unique admissible parameter set. Based on this result, we discuss the pricing problems of QTSMs under default-free and defaultable rates.