Measuring quark-gluon-plasma thermalization time with dileptons.
We calculate the medium dilepton yield from a quark-gluon plasma which has a time-dependent local momentum-space anisotropy. A phenomenological model for the hard momentum scale, p(hard)(tau), and plasma anisotropy parameter, xi(tau), is constructed which interpolates between longitudinal free streaming at early times (tau<<tau(iso)) and ideal hydrodynamic at late times (tau>>tau(iso)). We show that high-energy dilepton production is sensitive to the plasma isotropization time, tau(iso), and can therefore be used to experimentally determine the time of onset for hydrodynamic expansion of a quark-gluon plasma and the magnitude of expected early-time momentum-space anisotropies.
Martinez
Mauricio
M
Helmholtz Research School, Johann Wolfgang Goethe-Universität Frankfurt, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main, Germany.
Strickland
Michael
M