How to find branching ratio after modelling Lagrangian?

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zaman786
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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.

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