Definition of Jackson Angle

[wellatiger]

Dear Experts,

I am studying the reaction p(beam)+p(target) → p + K + Lambda.

I have a question on how to define the Jackson angle (explained in “https://arxiv.org/pdf/1008.4287.pdf” section 2.3.2). Basically it is the polar angle between the daughter proton and the proton beam in the rest frame of the Lambda and the daughter proton..

What I am doing is:

//  make a copy of the original 4-vector
TLorentzVector Proton(p), pbeam(pbeam);
//  define the rest frame of Proton+Lambda
TLorentzVector System(Proton + Lambda);
// boost Proton and pbeam into the System
pbeam.Boost(-System.BoostVector());
Proton.Boost(-System.BoostVector());

float JacksonAngle = pbeam.Vect().Dot(Proton.Vect()) / (pbeam.Vect().Mag()*Proton.Vect().Mag());

I was wondering if this is the correct way to do it?!

Many thanks in advance

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[moneta]

Hi,
At first sight it looks correct to me, but I will check if it is what expected, for example looking at the sum of the transformed 4 vectors of proton and lambda that should be equal to zero

Lorenzo