info about momentum of incoming particles

hi sorry to bother you again.
this is my code:
process eeprovamultifasci = A, e1 => e1,e1,E1

beams = A, e1 => gaussian

beams_momentum = 5 keV, 5 GeV

gaussian_spread1= 0%

gaussian_spread2= 10%

plot E_Theta_Px_Py_E1

plot E_Theta_Px_Py_e1

plot E_Theta_Px_Py_e2

sample_format = mokka

  integrate (eeprovamultifasci)

  scan real y=(0=>20/+1){

     real x= y*0.0001-0.001

     beams_theta = 0,x

     real z=(x*x)/(0.0003)^2

     n_events=10000*exp(-z)

     !luminosity = 1 / 2.e8 fbarn)

    #?rebuild_events = true

 $sample = sprintf "eeff_%1.3f_%1.3f" (real (y), real (x))

analysis= record E_Theta_Px_Py_E1 (eval E["E1"], eval Theta["E1"], eval Px["E1"],eval Py["E1"]) and

          record E_Theta_Px_Py_e1 (eval E[extract index 1 [e1]], eval Theta[extract index 1 [e1]], eval Px[extract index 1 [e1]],eval Py[extract index 1 [e1]])

          and

          record E_Theta_Px_Py_e2 (eval E[extract index 2 [e1]], eval Theta[extract index 2 [e1]], eval Px[extract index 2 [e1]],eval Py[extract index 2 [e1]])

  simulate (eeprovamultifasci)

}

compile_analysis

This simulation generates a lot of .mokka.evt files for every simulation and in these files i should see (for incoming particles) theyr 3 momentum components(px,py,pz) and theyr masses in the last 4 columns.
My doubt is that for incoming particles i only have momentum along pz , i don't understand why.
I'm doing a lots of simulation where i change the angle of interaction between incoming photons and electrons(beams_theta=0,x) so i expect my incoming particles have transverse momentum(px,py), did i do something wrong?
Thanks again,
Kind regards