Are resonances formed in the scattering of a baryon and a meson?

In summary, the conversation discusses a reaction of strong interaction where a particle called ##\Lambda_0## is formed and then decays with weak interaction. The four momenta of the particles in the final state are measured and the center-of-mass energy of the reaction is calculated. The cross section is then plotted against the center-of-mass energy. The question is whether this will result in a Breit Wigner resonance curve with a central value equal to the sum of masses of ##\Lambda_0## and ##K^+## and a width equal to the characteristic time of strong interaction. It is clarified that while reaction ##(2)## is a decay, reaction ##(1)## is not, and the question arises
  • #1
crick
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Consider the following reaction of strong interaction (in a scattering process)
$$n+\pi^+\to \Lambda_0+K^+\tag{1}$$

Then the particle ##\Lambda_0## formed decays with weak interaction

$$\Lambda_0\to \pi^+ +p\tag{2}$$

For each decay process I measure the four momenta of ##K^+##, ##\pi^+## and ##p## in the final state, I calculate the center-of-mass energy ##\sqrt{s}## of reaction ##(1)##. Then I plot the cross section vs ##\sqrt{s}##.

Do I get a Breit Wigner resonance curve with central value equal to the sum of masses of ##\Lambda_0## and $K^+$ and width equal to $$\Gamma=\hbar/\tau$$
Where ##\tau## is ##\sim 10^{-23}s##, i.e. the characteristic time of strong interaction?

I'm not sure about this because reaction ##(1)## is not a "decay" (while reaction ##(2)## is a decay) and I wonder if the resonances in the cross section are seen also in reactions that are not really a decay.

I suppose that in reaction ##(1)## a kind of "intermediate excited state" is formed and then it decays to the final state, but I'm quite confused about this.
 
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  • #2
You'll get a curve that starts at the sum of the two masses and increases afterwards due to increasing phase space to produce the particles. The timescale of the interaction or the lifetimes of the particles are irrelevant. The excess energy just goes into kinetic energy of the two produced particles.
 
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1. What is a resonance in the context of particle scattering?

A resonance in the context of particle scattering is a temporary state in which a particle is created and then quickly decays into other particles. This can occur when a baryon (a subatomic particle made up of three quarks) and a meson (a subatomic particle made up of a quark and an antiquark) interact with each other.

2. How are resonances formed in the scattering of a baryon and a meson?

Resonances are formed in the scattering of a baryon and a meson when the two particles interact with each other and exchange energy. This can result in the creation of a new particle, which is the resonance. The resonance then quickly decays into other particles.

3. What is the significance of studying resonances in particle scattering?

Studying resonances in particle scattering allows scientists to better understand the fundamental building blocks of matter and the strong force that holds them together. It also provides insights into the properties and behavior of these particles and their interactions.

4. How do scientists detect and study resonances in particle scattering?

Scientists use high-energy particle accelerators to create collisions between baryons and mesons. They then analyze the particles produced in these collisions and look for patterns or anomalies that may indicate the presence of a resonance. This data is used to study the properties and behavior of the resonance.

5. Can resonances be observed in nature outside of particle accelerators?

Yes, resonances can also be observed in nature outside of particle accelerators. For example, cosmic rays (high-energy particles from outer space) can create collisions in Earth's atmosphere that result in the production of resonances. Scientists can study these naturally occurring resonances to gain a better understanding of the properties and behavior of these particles.

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