Narrow-width approximation

In summary, the conversation discusses the difference between using or not using the narrow-width approximation (NWA) in a process involving the production and decay of a particle with a mass of 2 TeV and a dominant decay channel of x > b b~. The use of NWA results in a cross section of approximately 10^-5 pb, while not using NWA gives a cross section of 10^-6 pb. This difference is explained by the fact that NWA takes into account the branching ratio of the decay channel, resulting in a more accurate approximation. Additionally, the conversation touches on the concept of the partial width of x > b b~, which is approximately 5% of the mass of x.
  • #1
Safinaz
259
8
Hi all,

I try to understand the difference which can made by using or not using NWA ..
I have a process have cross section (p p > x x) ~ 10^-5 pb , where x is a paricle have mass mx = 2 TeV
and dominant decay channel (x > b b~) with Gamma (x > b b~) ~ 6 * 10^2 GeV ,
while sigma ( p p > x x , x > b b~) ~ 10^-6 pb (I calculate this with a program not using the NWA)..

It's clear that if NWA is used sigma ( p p > x x , x > b b~) will just ~ 10^-5 pb since BR (x > b b~) =1,
so what does mean 10^-5 (NWA) and 10^-6 (non- NWA)

Is that what meant by that NWA has ## \Gamma/m ## approximation ?

Regards,
Safinaz
 
Last edited:
Physics news on Phys.org
  • #2
Let me try to understand more.

Are you pair producing these two new particles? Then looking at the final state of 4 bs?

And your partial width of x>b bbar is 5% of the mass of x?
 
  • #3
Hi,
I think I get it, thanks.
S.
 

What is the narrow-width approximation?

The narrow-width approximation is a technique used in particle physics to simplify calculations involving particles with very short lifetimes. It assumes that the particle's width (the inverse of its lifetime) is much smaller than its mass, allowing certain terms in the equations to be neglected.

When is the narrow-width approximation valid?

The narrow-width approximation is valid when the particle's width is significantly smaller than its mass. This typically applies to particles with very short lifetimes, such as certain types of mesons and baryons.

What are the limitations of the narrow-width approximation?

The narrow-width approximation is not accurate for particles with longer lifetimes, as their width cannot be neglected compared to their mass. It also does not take into account any interactions or decays of the particle, and is only valid at the energy scale at which it was derived.

How is the narrow-width approximation useful in particle physics?

The narrow-width approximation simplifies calculations and allows for more precise predictions of the behavior of particles with short lifetimes. It is often used in the study of high-energy collisions and decays of particles at particle accelerators.

What other approximations are used in particle physics?

In addition to the narrow-width approximation, other commonly used approximations in particle physics include the heavy quark limit, the large-N limit, and the chiral limit. These approximations are used to simplify calculations and make predictions about the behavior of particles under certain conditions.

Similar threads

  • High Energy, Nuclear, Particle Physics
Replies
2
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
13
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
1
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
11
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
4
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
13
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
6
Views
4K
  • Calculus and Beyond Homework Help
Replies
2
Views
564
  • Differential Equations
Replies
1
Views
624
  • High Energy, Nuclear, Particle Physics
Replies
14
Views
1K
Back
Top