Why are particles produced in jets?

[coca12]

Hi,

I'm having trouble understanding jets.


After say, the initial collision, I get that you have a bunch of quarks and gluons left over.
And that they must hadronize into colorless objects. But I'm not sure I get the jets part.
I understand if we have two quarks that around bound together by a gluon (or string or whatever), that due to the strong force, if the energy in separating them is enough we'll
produce a qqbar pair and all these are kept together in a jet by lots of gluons keeping them
that way.


But what about this: Say, one of the hadrons created is a B meson which decays like
B+ ->D0 mu+ nu

We expect that the decay products will be collinear with the parent B, and that the subsequent
decay products of the D0 will be collinear with the D0.

But why is that if this is a weak decay?

If we're below the confinement scale, and the hadronization process has finished, what's keeping all this stuff together?

 

[alsey42147]

if the momentum of the B is large (in the lab frame) then the decay products are boosted and hence have small transverse momentum relative to the B momentum. a B is quite a heavy hadron so this boost effect is smaller than in a light flavour jet, which is why b jets are generally broader than light flavour jets.

if the B is produced at rest (like in BaBar for example), then the decay will be isotropic and not jet-like.