I have been assigned to analyze this circuit below(it's an improvement to a differential amplifier in order to have better BandWidth):

like a differential amplifier , i tried to find the half-circuit and i came up with this:

in order to find the transfer function i used hybrid-pi model but now I'm stuck with a problem: that there is no connection between the two transistor and the second transistor seems non-functional so how can i find the transfer function? have i done any mistake in a part of solution?