Nuclear stability and variations of SM params

In summary, the conversation discusses the sensitivity of nuclear stability to small variations in fundamental parameters, such as the fine-structure constant, strong force, and quark masses. It is estimated that a 1% change in these parameters can result in a 2% change in the coulomb term and a few more neutrons needed for stability. A change in the weak interaction or W boson mass can also affect the half-life of beta decays. Cosmology is also mentioned as being sensitive to changes in fundamental parameters, as it can impact the structure and stability of stars.
  • #1
Dmitry67
2,567
1
I am looking at this pretty chart:

http://upload.wikimedia.org/wikipedia/commons/8/80/Isotopes_and_half-life.svg

My question is, how sensitive is it to the variation of SM parameters?
Imagine that I am sitting in front of some magic TV, where the image above is displayed. Below there are sliders, one per SM parameter. I start to move these sliders, looking at the screen.

So how sensitive is function of nuclear stability to the small variation of parameters, how much do I need to change to start seeing any difference or to completely change they way how it looks?

Of course there are no exact answers, but any rough estimations - like 1%, 0.01%, or 0.00000001%?
 
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  • #2
You can extract the general shape of that diagram with the mass formula. The coefficients depend on fundamental parameters - not strictly linear, but at least something similar.

If you increase the fine-structure constant by 1%, the coulomb term will increase by 2%, and large nuclei need a few neutrons more to be stable (similar to 2%, I would guess, which corresponds to ~3-5 neutrons).

If you increase the strong force by 1%, volume and surface term will change in a similar way, and I would expect that more (heavier) nuclei become stable or long-living.

If you change the up- or down-quark masses, the ratio protons/neutrons will change a bit.

If you change the strength of the weak interaction or the W boson mass, you change the half-life of beta decays. That influence is certainly nonlinear.

Other constants: Hmm...

Cosmology can be more sensitive to some changes - if neutrons would be >0.5 MeV lighter than protons for example, protons would decay to stable neutrons, and stars (if they would exist at all) would look completely different. The Triple-alpha_process is quite sensitive to energy states, too.
 

1. What is nuclear stability?

Nuclear stability refers to the ability of an atomic nucleus to remain intact and not undergo radioactive decay. This is determined by the balance of protons and neutrons in the nucleus, as well as the strength of the nuclear forces holding the nucleus together.

2. How do variations in Standard Model parameters affect nuclear stability?

The Standard Model of particle physics describes the fundamental particles and forces of nature. Variations in its parameters, such as the strength of the strong nuclear force, can affect nuclear stability. For example, if the strong nuclear force were weaker, fewer nuclei would be stable and more would undergo radioactive decay.

3. What are the consequences of unstable nuclei?

Unstable nuclei can undergo radioactive decay, emitting particles and/or energy in order to become more stable. This can have various effects, such as altering the composition of an element or releasing harmful radiation.

4. Can nuclear stability be altered artificially?

Yes, nuclear stability can be altered artificially through processes such as nuclear fission and fusion. These processes involve splitting or combining nuclei to create new, more stable nuclei. However, these methods can also have potentially dangerous consequences.

5. How do scientists study nuclear stability and variations of Standard Model parameters?

Scientists use a variety of experimental techniques, such as particle accelerators and nuclear reactors, to study nuclear stability and variations of Standard Model parameters. They also use mathematical models and simulations to understand the underlying principles and predict outcomes.

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