  I present a general framework allowing to carry out explicit calculation of
the moment generating function of random matrix products
$\Pi_n=M_nM_{n-1}\cdots M_1$, where $M_i$'s are i.i.d.. Following Tutubalin
[Theor. Probab. Appl. {\bf 10}, 15 (1965)], the calculation of the generating
function is reduced to finding the largest eigenvalue of a certain transfer
operator associated with a family of representations of the group. The
formalism is illustrated by considering products of random matrices from the
group $\mathrm{SL}(2,\mathbb{R})$ where explicit calculations are possible. For
concreteness, I study in detail transfer matrix products for the
one-dimensional Schr\"odinger equation where the random potential is a L\'evy
noise (derivative of a L\'evy process). In this case, I obtain a general
formula for the variance of $\ln||\Pi_n||$ and for the variance of
$\ln|\psi(x)|$, where $\psi(x)$ is the wavefunction, in terms of a single
integral involving the Fourier transform of the invariant density of the matrix
product. Finally I discuss the continuum limit of random matrix products
(matrices close to the identity ). In particular, I investigate a simple case
where the spectral problem providing the generalized Lyapunov exponent can be
solved exactly.
