# Questions tagged [fine-tuning]

"Fine-tuning" is a situation in which the fundamental parameters in a theory must be "fine-tuned", i.e. precisely chosen, in order for a theory's predictions to agree with experimental data.

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### How does the Higgs being a Goldstone Boson (in new models) protects its mass from quadratic corrections?

I understand how a symmetry protects a mass from this type of correction: It is known that a symmetry is not broken by corrections of any order -- this hints that if a mass term is forbidden by an ...
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### A finer tuned universe [closed]

I was reading about the idea of the fine-tuned universe and the anthropic principle. It is stated how small changes in some of the physical constants would render life as we know it impossible. My ...
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### Fine Tuned Universe Numbers

I come across many articles for interested lay people telling us that our universe is fine-tuned for life. For example, if the weak force was a little bit weaker, than almost all of the hydrogen ...
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### Is the hierarchy problem definitely a "problem"?

There have been a bunch of questions related to the hierarchy problem, but I still can't help but feel that an assumption is being made that is not backed by any example of correctness and is thus ...
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### Does multiverse theory obviate the need for fine tuning?

I recently read the book by Max Tegmark, The mathematical Universe, where he expounds upon the multiverse and how if ANYTHING can happen, will happen, because of all the ways things can be arranged. I ...
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### Source of hierarchy problem for fermions and bosons

In the beginning of a SUSY course, we computed $1$-loop level corrections to the mass of a bosons $\phi$ and a fermion $\psi$ in the theory \begin{align} \mathcal{L} &= \bar{\psi}(i\gamma^\mu D_\...
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### Would extra dimensions really solve the hierarchy problem?

The hierarchy problem revolves around the fact that we don't have a way to explain why gravity is so much weaker than the other forces. It may just be a coincidence, but since physicists tend to ...
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### The hierarchy problem: Higgs mass correction from gauge boson loop

From this article Fine Tuning Problem (Perez, Weizmann Institute of Science, Lecture Note) in section C, the hierarchy problem arises from the fact that there are quadratically divergent loop ...
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### How SUSY solves the hierarchy problem?

I am struggling to understand the argument for why the introduction of a stop in SUSY can solve the hierarchy problem. The quadratic divergence from the top loop in the higgs mass calculation gives a ...
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### Confusion about choice of renormalization scale in $\overline{\rm MS}$ mass

The $\overline{\rm MS}$ mass is function of the renormalization scale $\mu$. What does it mean to choose this scale $\mu$ as the $\overline{\rm MS}$ mass itself? I am giving some details below to make ...
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### $\theta$ angle QCD technically natural

Why exactly does the observed smallness of the $\theta$-angle in QCD constitute a fine-tuning problem? I thought that the content of 't Hooft's technical naturalness was exactly that a parameter is ...
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### Hierarchy problems: calculating the mass of the Higgs vs. other SM particles

While reading up on hierarchy problems in particle physics (wikipedia), I stumbled onto the statement that in the Standard Model, there is no hierarchy problem (or at least it cannot be formulated) ...
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### What really enforces technical naturalness of electron mass?

Technical or 't Hooft naturalness A parameter $\theta$ in the Lagrangian of a field theory is said to be natural, if in the limit of vanishing $\theta$, the theory has some enhanced symmetry. If this ...
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### Why is the up quark is lighter than the down quark, while top is heavier than bottom?

Up, charm and top seem to be similar in terms of electric charge (+2/3e) while down, strange and bottom have also same charge (-1/3e). In the second and third family, positively charged quark has ...
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### Fine Tuning of the Universe

I'm an A level student looking into the fine tuning of various constants. Physicists explain the extensive effects that would happen if these constants were to be changed/different and hence, how this ...
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### Is naturalness meaningful for non-fundamental theories?

Naturalness has been a guiding philosophy for particle physics for a long time, but a few years ago I heard a talk by Nima Arkani-Hamed where he pointed out that it seems to have failed us as it ...
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