How to find branching ratio after modelling Lagrangian?

In summary, to find the branching ratio after modeling a Lagrangian, one must first derive the interaction terms from the Lagrangian that describe the decay process. Then, calculate the decay widths (Γ) for the various decay channels using perturbation theory. The branching ratio for a specific decay channel is obtained by dividing its decay width by the total decay width of the process. Finally, ensure that all relevant factors, such as phase space and coupling constants, are accurately accounted for in the calculations to obtain precise results.
  • #1
zaman786
31
6
TL;DR Summary
to find branching ratio after modelling Lagrangian
hi, we have learned that after modelling Lagrangian and extracting Feynman rules from it - we can find matrix element - from which decay width can be calculated - and than Branching ratio - my question is can we use some other way of calculatiing BR , or can we use our Lagrangain in our Euler -Lagrangian equation - from there we can find out Branching ratio ?
 

FAQ: How to find branching ratio after modelling Lagrangian?

What is a branching ratio in particle physics?

A branching ratio in particle physics is the fraction of a particle decay process that results in a particular set of final states compared to the total number of decays. It quantifies the likelihood of a specific decay channel among all possible decay channels.

How do I identify the relevant interaction terms in the Lagrangian?

To identify the relevant interaction terms in the Lagrangian, you need to isolate the terms that describe the interactions between the initial and final state particles of interest. These terms typically involve the fields corresponding to the particles and the coupling constants that determine the interaction strength.

How do I calculate the decay width from the Lagrangian?

To calculate the decay width from the Lagrangian, you need to use Feynman rules to derive the matrix element for the decay process. Then, you integrate over the phase space of the final state particles to obtain the decay width, which is proportional to the square of the matrix element.

How do I normalize the decay width to find the branching ratio?

To normalize the decay width and find the branching ratio, you divide the decay width of the specific channel by the total decay width of the particle. The total decay width is the sum of the decay widths of all possible decay channels for the particle.

What tools or software can help in calculating branching ratios?

Several tools and software can assist in calculating branching ratios, such as FeynRules, MadGraph, and CalcHEP. These tools can help automate the process of deriving Feynman rules from the Lagrangian, calculating matrix elements, and integrating over phase space to obtain decay widths and branching ratios.

Similar threads

A Branching ratio for one decay channel
Replies
6
Views
2K
A How Does the ss¯ Pair Affect the Partial Width Γ2 in Gluon Decays?
Replies
4
Views
2K
A Branching ratios | Higgs phenomenology
Replies
13
Views
2K
I How to find the most likely modes of decay for a particle
Replies
3
Views
2K
I Algorithmic model for primary decay chains
Replies
1
Views
1K
A What Are the Possible Decay Processes of the W⁻ Boson?
Replies
1
Views
2K
I Matrix Elements via Feynman Diagrams
Replies
1
Views
3K
I Find Lambda Baryon Decays Cross Section Ratio
Replies
6
Views
4K
A Understanding the Use of Trace in QFT Lagrangian for Chiral Symmetry in QCD
Replies
1
Views
3K
I How do the collider experiments measure the mass of the W boson?
Replies
4
Views
3K

Hot Threads

Recent Insights

Back
Top