  Using the framework of wedge dynamics, we compute the effective transverse
mass of a soft quark mode propagating in the expanding background of hard
quarks and gluons created at the earliest time of the collision. We discover
that the wedge dynamics does not require any external infrared or collinear
cut-off. The effective mass is produced mainly due to the forward quark-quark
scattering mediated by the longitudinal (in sense of Gauss' law) magnetic
fields. Contribution of the radiation field is parametrically suppressed.
