The explicit asymptotic formula of divisor function on average over values of quadratic polynomial

Let $F({\bf x})={\bf x}^tQ_{\bf x}+$\mathbf{b}$^t{\bf x}+c\in$\mathbb{Z}$[{\bf x}]$beaquadraticpolynomialin$\ell (\ge 3 )$variables${\bf x} =(x_{1},…,x_{\ell})$,where$F({\bf x})$ispositivewhen${\bf x}\in$\mathbb{R}${\ge 1}^{\ell}$,$Q\in {\rm M}{\ell}($\mathbb{Z}$)$isan$\ell\times\ell$matrixanditsdiscriminant$\det\left(Q^t+Q\right)\neq 0$. It gives an explicit asymptotic formula for the following sum $$\sum _{\mathbf{x}\in [1,X{]}^{\mathrm{\ell }}\cap {\mathbb{Z}}^{\mathrm{\ell }}}\tau (F(\mathbf{x})),$$ where $\tau$ is the divisor function.