  High-energy heavy-ion collisions generate extremely strong magnetic field
which plays a key role in a number of novel quantum phenomena in quark-gluon
plasma (QGP), such as the chiral magnetic effect (CME). However, due to the
complexity in theoretical modellings of the coupled electromagnetic fields and
the QGP system, especially in the pre-equilibrium stages, the lifetime of the
magnetic field in the QGP medium remains undetermined. We establish, for the
first time, a kinetic framework to study the dynamical decay of the magnetic
field in the early stages of a weakly coupled QGP by solving the coupled
Boltzmann and Maxwell equations. We find that at late times a
magnetohydrodynamical description of the coupled system emerges. With respect
to realistic collisions at RHIC and the LHC, we estimate the residual strength
of the magnetic field in the QGP when the system start to evolve
hydrodynamically.
