Branching ratio for one decay channel

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Discussion Overview

The discussion revolves around the process of determining the branching ratio for a specific decay channel of a particle, particularly focusing on the D0 meson. Participants explore the relationship between decay width measurements and branching ratios, considering both theoretical calculations and experimental approaches.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the necessity of measuring the decay width of all possible decay channels to find the branching ratio, expressing concern about potentially missing some decay modes in experiments.
  • Another participant emphasizes the importance of knowing the starting point of the inquiry to provide appropriate guidance.
  • A participant mentions that for the D0 meson, they can find the decay width for specific decay modes but questions whether they need to account for all decay modes to compute the total decay width and subsequently the branching ratio.
  • Some participants suggest that theoretically, all decay modes should be calculated, or at least the major ones, while neglecting rare modes, as the ratios of branching fractions are typically unaffected by these rare decays.
  • One participant notes that calculating all possible channels is essential for theoretical calculations but also mentions the possibility of performing an inclusive measurement of the total decay width, which would account for all decay modes, including rare ones.
  • It is highlighted that the uncertainty in measurements of total decay width and single channel decay widths can be significant, suggesting that missing rare decays may not materially affect the accuracy of the branching fraction calculations.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of accounting for all decay modes in theoretical calculations and measurements. While some argue for the inclusion of all major decay modes, others suggest that rare decays can be omitted without significant impact on the results. The discussion remains unresolved regarding the best approach to take.

Contextual Notes

Participants acknowledge the potential for missing decay modes in experimental measurements and the associated uncertainties in decay width calculations, which may influence the determination of branching ratios.

zaman786
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TL;DR
how can we find the branching ratio - after do calculation for one channel
hi, for studying one decay channel of particle - and measuring its decay width or life time - after this how do we proceed to find the branching ratio -
do we need to find the decay width of all possible channel - because its possible even by experiment we are missing some possible decay mode.
kindly help
 
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Where are you starting from? Can't give you directions from here to there without knowing where "here" is.
 
Vanadium 50 said:
Where are you starting from? Can't give you directions from here to there without knowing where "here" is.
for example D0 meson has several semi-leptonic decay - i want to find its branching ratio for k-, positron and electron neutrino , i can find its decay width
but it has different mode or channel also exist as mention in PDG , so do i have to find decay width for all of these modes and get total decay width. than by using formula : Branching ratio = partial decay width/ total decay width
or there exist some easiest approach
 
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If you want to do this purely theoretically then you need to calculate all decay modes, or at least all major decay modes and then neglect the rare ones. Typically theoretical results will compare one branching fraction to another, the ratio won't be affected by other decay modes. That is easier to measure experimentally as well.
 
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mfb said:
If you want to do this purely theoretically then you need to calculate all decay modes, or at least all major decay modes and then neglect the rare ones. Typically theoretical results will compare one branching fraction to another, the ratio won't be affected by other decay modes. That is easier to measure experimentally as well.
thanks a lot for clearing my confusion
 
zaman786 said:
do we need to find the decay width of all possible channel - because its possible even by experiment we are missing some possible decay mode.
Calculating all possible channels is how you would make the theoretical calculation.

You could also do an inclusive measurement of the decay width of the entire hadron (looking at its resonance) which would measure the total decay width, including decays that are rare enough to not be detected individually.

Rare decays are so uncommon, and the measurements of total decay width and single channel decay widths have sufficient uncertainty (often 10-3 or worse), that missing a few rare decays (which often have branching fractions of 10-5 or less), doesn't change the branching fraction enough to be distinguishable given the uncertainties involved in your other calculations and measurements. So, you can safely omit rare decays from the theoretical total decay width without materially changing the accuracy of your calculation.
 
surely, you have given hint - looking at its resonance - thanks , i will look into it-
thanks a lot
 
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