Time it takes for a particle creation/annhilation (according to QFT)?

triclon
Messages
12
Reaction score
0
I am curious if quantum field theory says anything about how much time it takes for an interaction, or particle creation and annihilation, to take place. For example if I have a high energy photon, and it strikes an atomic nucleus and you get pair production forming an electron and positron. In the example, I am wondering what is the amount of time it takes to go from a photon to an electron and positron. Is there a certain amount of time for that process to occur or is it "instantaneous" where one moment you have a high energy photon and a nucleus at rest, and the next you have an electron and positron? I don't know enough about QFT to say. Perhaps the theory doesn't probe into the "process" of the interaction and can't say anything about the time it takes for it to occur? Or does theory have something to say?
 
Physics news on Phys.org
The interaction occurs at a single point in spacetime. However, keep in mind that you're really just saying that there's an amplitude at every point in spacetime for the interaction to take place.
 

Thread 'Toponium Discovered'

Toponium is a hadron which is the bound state of a valance top quark and a valance antitop quark. Oversimplified presentations often state that top quarks don't form hadrons, because they decay to bottom quarks extremely rapidly after they are created, leaving no time to form a hadron. And, the vast majority of the time, this is true. But, the lifetime of a top quark is only an average lifetime. Sometimes it decays faster and sometimes it decays slower. In the highly improbable case that...
View full post »

Thread 'Dirac-Delta from Normalization of Continuous Eigenfunctions'

I'm following this paper by Kitaev on SL(2,R) representations and I'm having a problem in the normalization of the continuous eigenfunctions (eqs. (67)-(70)), which satisfy \langle f_s | f_{s'} \rangle = \int_{0}^{1} \frac{2}{(1-u)^2} f_s(u)^* f_{s'}(u) \, du. \tag{67} The singular contribution of the integral arises at the endpoint u=1 of the integral, and in the limit u \to 1, the function f_s(u) takes on the form f_s(u) \approx a_s (1-u)^{1/2 + i s} + a_s^* (1-u)^{1/2 - i s}. \tag{70}...
View full post »

Similar threads

I How does a photon interact with the EM field of a nucleus?
Replies
14
Views
2K
A Why KE of Annihilation Electrons Differs?
Replies
11
Views
2K
I How prone is a photon to interacting with uncharged structureless particles?
Replies
8
Views
3K
I How often would a ϕ meson decay to a electron-positron pair?
Replies
2
Views
2K
B What does QFT really predict about matter/anti-matter interactions?
Replies
6
Views
2K
B Can a hypothetical atom be made out of positrons and electrons ?
Replies
9
Views
3K
I Particle exchange explaining attractive forces
Replies
12
Views
3K
A The fractional energy loss of charged particle per radiation length
Replies
1
Views
2K
I Does a photon experience time while interacting with the weak force?
Replies
6
Views
2K
I Probing into protons with high-energy particles
Replies
10
Views
2K

Hot Threads

Recent Insights

Back
Top