Compute Breit-Wigner for particle decay

• mefistofeles
In summary, the conversation is about computing the Breit-Wigner for a particle decay and using it for nonlinear fitting of data. The expression for the Breit-Wigner is posted on a website, but the individual is having trouble understanding the math involved, particularly the use of the imaginary unit. After some discussion, it is clarified that the imaginary part of the expression gets squared in the denominator, resulting in a real final result.
mefistofeles
Hey, I am just woondering if anyone here have computed (numerically) the Breit-Wigner for a particle decay. I have to do some nonlinear fitting of data but I need to compute this, any ideas?

My case is specific, and I am brand new to particle physics, it's for a tau decay into Kaon, pion and tau neutrino. The expression I have for the Breit-Wigner is posted in: http://mathbin.net/5566

I still don't understand the math beneath the expression. All I am asked is to compute it, what I am having trouble with is that i on the Breit-Wigner, I am not sure if that's the imaginary unit or something different, so if you know please help me compute this. Thanks for the attention.

Last edited by a moderator:
OK I gave it a second thought and I got it, that BW (for that decay) appears inside a function which is squared, so the imaginary part actually disappears, should have seen this before posting heh, sorry.

The I am doesn't disappear, but gets squared in the denominator.

OK, that's what I meant by "disappear", sorry the non-technical term. And you are right, it gets squared so that i^2 = -1 and the final result is real which corresponds to the "magnitude" of the complex number.

No. You take the complex conjugate so (i)(-i)=+1.

1. What is the Breit-Wigner formula used for in particle decay computations?

The Breit-Wigner formula is a mathematical formula used to describe the probability of a particle decaying into different final states. It is commonly used in particle physics to model the resonance behavior of unstable particles.

2. How is the Breit-Wigner formula related to the concept of resonance?

The Breit-Wigner formula is used to describe the behavior of particles near their resonance energy, where they are most likely to decay. It takes into account the energy width of the particle, which is related to its lifetime, and the probability of the particle decaying into different final states.

3. What are the key parameters in the Breit-Wigner formula and what do they represent?

The key parameters in the Breit-Wigner formula are the mass of the particle, the width of the particle, and the energy of the particle. The mass represents the energy needed for the particle to decay, the width represents the uncertainty in the mass due to the particle's lifetime, and the energy represents the energy at which the particle is most likely to decay.

4. How is the Breit-Wigner formula used in data analysis for particle physics experiments?

In particle physics experiments, the Breit-Wigner formula is used to fit experimental data to theoretical models. By adjusting the parameters in the formula, researchers can determine the mass and width of a potential new particle, and compare it to known particles to confirm its existence.

5. Are there any limitations to the Breit-Wigner formula in particle decay computations?

While the Breit-Wigner formula is a useful tool for describing the behavior of unstable particles, it does have limitations. It assumes that the particles are in a vacuum and that all decay channels are equally likely. In reality, there may be other external factors, such as interactions with other particles, that can affect the decay process.

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