Permanent switch of regimes and one with smaller number of variables

General DSGE Modeling
1

Dear Forum,

Is there a DSGE model where there are 2 regimes of the economy but there is a permanent switch from one regime to another? Moreover the number of variables is smaller in regime 1 than regime 2, for example, government introduced bond in 2nd regime but in 1st regime the bond did not exist.

Thank you very much in advance.

2

There are sure models like that out there. Some ZLB papers come to mind where the ZLB is triggered once and then the model permanently transitions to the baseline regime. But that is often done out of analytical convenience. I am not aware of numerical models that do that.