Boosting e- to Z-boson rest frame using TLorentzVector

Newbie
,
1

Hi,

I am trying to boost my electron to the rest frame of the Z-boson. I am doing this in python using uproot and ROOT.TLorentzVector. My problem is that the code works when I boost the particle to its own rest frame, but not when I boost to a different particles rest frame. A perspective would be greatly appreciated.

# Boost electron to Z rest frame
electron = ROOT.TLorentzVector(e_px, e_py, e_pz, e_E) # lab frame values
Z_boson = ROOT.TLorentzVector(Z_px, Z_py, Z_pz, Z_E) # lab frame values

electron_boosted = ROOT.TLorentzVector(electron)  # Copy the electron vector
electron_boosted.Boost(-Z_boson.BoostVector())  # Boost to Z rest frame

# Get the boosted electron's momentum components
e_px_rest = electron_boosted.Px()
e_py_rest = electron_boosted.Py()
e_pz_rest = electron_boosted.Pz()

Here is a comparison of the maximum values from the e- and Z in the lab frame vs boosted frame.

  • max e lab 2712
  • max Z lab 3381
  • max e boosted 60658

This is clearly incorrect as the electron is being boosted to 60 TeV, when it should be around the same order of magnitude as the Z boson.

ROOT Version: 6-30-02
Python Version: 3.9.12
Platform: Mac

2

Hi @Chris_G,

thanks for reaching out!

TLorentzVector is legacy code, do you still encounter this inconsistency when using the modern interface?

Cheers,
Monica

3

Hi @mdessole

Thank you for your response! I did not know TLorentzVector is a legacy code, so I will try with the modern interface.

Many thanks!