The columns in the CMS data files are:
- E: energy, in GeV
- px, py, pz: cartesian components of momentum, in GeV/c
- pt: tranverse momentum (in the x-y plane, perpendicular to the beam pipe), in GeV/c
- phi: polar coordinate of the initial trajectory in the transverse plane, in radians
- eta: a function of the initial trajectory's angle with respect to the beam pipe (like theta), called pseudorapidity. Eta is a function of theta where eta = 0 is the transverseplane and eta = +/- infinity at the beam pipe
- Q: charge, in units of fundamental charge, e
- E1, px2, etc: properties of one of multiple particles detected
- MET: the event's missing transverse energy (in single lepton datasets), in GeV