  The origin of extremely fast variability is one of the long-standing
questions in the gamma-ray astronomy of blazars. While many models explain the
slower, lower energy variability, they cannot easily account for such fast
flares reaching hour-to-minute time scales. Magnetic reconnection, a process
where magnetic energy is converted to the acceleration of relativistic
particles in the reconnection layer, is a candidate solution to this problem.
In this work, we employ state-of-the-art particle-in-cell simulations in a
statistical comparison with observations of a flaring episode of a well-known
blazar, Mrk 421, at very high energy (VHE, E > 100 GeV). We tested the
predictions of our model by generating simulated VHE light curves that we
compared quantitatively with methods that we have developed for a precise
evaluation of theoretical and observed data. With our analysis, we can
constrain the parameter space of the model, such as the magnetic field strength
of the unreconnected plasma, viewing angle and the reconnection layer
orientation in the blazar jet. Our analysis favours parameter spaces with
magnetic field strength 0.1 G, rather large viewing angles (6-8 degrees), and
misaligned layer angles, offering a strong candidate explanation for the
Doppler crisis often observed in the jets of high synchrotron peaking blazars.
