How do you know that a particle is strongly interacting?

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In summary, the discovery of particles other than nucleons led physicists to question how they knew these particles were "strongly" interacting. It was initially believed that the half-life or decay width of the particles was a determining factor, but it was later discovered that production also played a role. Strong interactions have a characteristic time scale of 10-23 sec, while most decays occur around 10-13 sec. However, the top quark, the shortest lived known particle, decays in a semi-weak interaction with an estimated lifetime of 5×10−25 sec. When distinguishing between particles like mesons, myons/tay leptons, and neutrinos, the half-life cannot be used as a determining factor, especially
  • #1
alemsalem
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when physicists discovered particles other than nucleons, before the quark model, how did they know they are "strongly" interacting, is it the half-life?
 
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  • #2
Yes, half-life i.e. decay width (and in general strength of interaction, i.e. scattering cross section, but that doesn not apply to outgoing particles, of course)
 
  • #3
No, not the half-life, it has to do with production. Particles are typically produced via strong interaction and decay via weak interaction. Strong interactions have a characteristic time scale of 10-23 sec, whereas most decays are 10-13 sec or thereabouts.

However the shortest lived known particle, the top quark, decays into a W boson and a bottom quark with an estimated lifetime of 5×10−25 sec. Even this is a semi-weak interaction.
 
  • #4
I think we are not talking about quarks but e.g. hadrons.

How do you distinguish a meson and its decay channels from a myon or tau lepton? or from a neutrino? especially when you are capturing data from cosmic radiation? via half-life of the paricle; production is not under control.
 
  • #5
Ok, here's a question for you. I have a particle with a mass of 1.8 GeV and an observed lifetime of 3 x 10-13 sec. From the relationship that you believe exists connecting a particle's lifetime with its strong interactions, tell me whether you think this particle is a hadron or a lepton.
 
  • #6
I cannot distinguish whether it's a hadron or a lepton, but I can GUESS that it decays only weakly.
 

1. How do you detect strong interactions between particles?

Strong interactions between particles can be detected through high-energy experiments, such as colliding particles at high speeds. This allows scientists to observe the behavior of particles and determine if they are strongly interacting through the amount of energy released during the collision.

2. What evidence supports the existence of strong interactions between particles?

There are several lines of evidence that support the existence of strong interactions between particles, including the stability of atomic nuclei, the observed behavior of subatomic particles, and the results of high-energy experiments. Additionally, the mathematical framework of quantum chromodynamics (QCD) provides a strong theoretical basis for understanding strong interactions.

3. How do you distinguish between strong and weak interactions between particles?

Strong interactions are typically characterized by the exchange of gluons between particles, whereas weak interactions involve the exchange of W and Z bosons. Additionally, strong interactions are much stronger than weak interactions, resulting in a much shorter range and more powerful effects.

4. Can particles have both strong and weak interactions?

Yes, particles can have both strong and weak interactions. In fact, all known particles possess both strong and weak interactions, although the strength of each interaction may vary. For example, protons have strong interactions that hold the nucleus together, but also experience weak interactions in processes such as beta decay.

5. What are the implications of strong interactions for our understanding of the universe?

Strong interactions play a crucial role in our understanding of the universe, as they are responsible for holding together atomic nuclei and allowing for the formation of stable matter. Additionally, the study of strong interactions has led to the development of important theories such as QCD, which have greatly advanced our understanding of the fundamental laws of nature.

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