AW: [ROOT] Help using TLorentzVector/TLorentzRotation

From: Malzacher Dr. Peter (P.Malzacher@gsi.de)
Date: Mon Mar 05 2001 - 09:30:46 MET


Dear Andres,

the simplest way to transform in x direction is to use the Boost method of
TLorentzVector:
  TLorentzVector v;
  ....
  betaX = .99; 
  v.Boost(betaX,0,0);

you may extract a boost vector from a LorentzVector:
  TLorentzVector v, w;
  ...
  v.Boost(w.BoostVector());
  ...
  
Only if you want a combination of different transformations you need the 
TLorentzRotation class. You are not allowed to initialize the components
by yourself, since in that case it is difficult to ensure that the
transformation has the correct properties. But you can use 
Boosts and Rotations to get the transformation you need, 
see  for example my recent answer to Matthieu Guillo: 
http://root.cern.ch/root/roottalk/roottalk01/0655.html

Peter 

> -----Ursprüngliche Nachricht-----
> Von: Andres Felipe Osorio [mailto:an-osori@isis.uniandes.edu.co]
> Gesendet: Samstag, 3. März 2001 10:33
> An: roottalk@pcroot.cern.ch
> Betreff: [ROOT] Help using TLorentzVector/TLorentzRotation
> 
> 
> Dear Rooters,
> 
>     I would like to do a Lorentz transformation to a 4-vector 
> of a particle
> going in x-direction. It´s not clear to me the mechanism to 
> declare the
> Lorentz transformation matrix which I need to perform this operation :
> /*
> TLorentzRotation l;
> TLorentzVector v;
>   ...
>   v=l.VectorMultiplication(v);
>   v = l * v;
> 
>   v.Transform(l);
>   v *= l;
> */
> 
> Then how can I put the components of this matrix l ?
> 
> Could anyone please give me a suggestion about how to do it?
> 
> Thank you very much,
> 
> Andres Felipe Osorio
> Fisica - Universidad de los Andes
> 
> 



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