Re: [Fwd: [ROOT] About Boost on TLorentzVector]

From: Pasha Murat (630)840-8237 FNAL (630)859-3463 home (
Date: Mon Oct 15 2001 - 05:19:38 MEST

> Suppose the decay a -> b+c , we know the 4 vectors of b and c.  We need
> to know the phi angle of b on the a rest frame. First, we  took the
> boost vector :
> TVector3 boost = -(b+c).BoostVector()
> then,
> b->Boost(boost);
> Could someone tell us which is the direction of the Z axis on the  "a"
> rest frame: the lab Z axis or the direction "a"? If we are doing
> something wrong, what is the right way to get this angle?

haven't seen this question answered, so:

both reference frames have their axes parallel, so Z-axis in the rest frame
of "a" coincides with the Z-axis in the lab frame.
							best, Pasha

P.S. this choice is pretty obvious: otherwise one needs a special effort
     to define direction of the axes in the rest frame of "a"...

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