  We prove a result on the large deviations of the central values of even
primitive Dirichlet $L$-functions with a given modulus. For $V\sim
\alpha\log\log q$ with $0<\alpha<1$, we show that
\begin{equation}\nonumber\frac{1}{\varphi(q)} \# \left\{\chi \text{ even,
primitive mod }q: \log \left|L\left(\chi,\frac{1}{2}\right)\right|
>V\right\}\ll \frac{e^{-\frac{V^2}{\log\log q}}}{\sqrt{\log\log
q}}.\end{equation} This yields the sharp upper bound for the fractional moments
of central values of Dirichlet $L$-functions proved by Gao, upon noting that
the number of even, primitive characters with modulus $q$ is
$\frac{\varphi(q)}{2}+O(1).$ The proof is an adaptation to the $q$-aspect of
the recursive scheme developed by Arguin, Bourgade and Radziwill for the local
maxima of the Riemann zeta function, and applied by Arguin and Bailey to the
large deviations in the $t$-aspect. We go further and get bounds on the case
where $V=o(\log\log q)$. These bounds are not expected to be sharp, but the
discrepancy from the Central Limit Theorem estimate grows very slowly with $q$.
The method involves a formula for the twisted mollified second moment of
central values of Dirichlet $L$-functions, building on the work of Iwaniec and
Sarnak.
