Skip to main content

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.

Filter by
Sorted by
Tagged with
1 vote
0 answers
63 views

Hierarchy Problem vs ratio of masses in the Standard Model

In the Standard Model, the ratio between the top quark's mass to the neutrinos is at least about $2 \times 10^{11}$. It could rise by at least an order of magnitude in the coming years as the ...
tomdodd4598's user avatar
1 vote
0 answers
47 views

The origin of the Hierarchy Problem

In the answer to this question on the origin of the hierarchy problem, it is stated that: The low-energy parameters such as the LHC-measured Higgs mass 125 GeV are complicated functions of the more ...
tomdodd4598's user avatar
0 votes
1 answer
33 views

Changing the frequency of the tuning forks

I just bought some tuning forks with frequencies of 128 Hz and 512 Hz. However, when I tested them using an app, their frequencies turned out to be lower than the specified values. How can I increase ...
zarvis12's user avatar
0 votes
0 answers
32 views

How solid state laser is tuned?

My understanding about solid state laser is sample as a source of exciting (lamp ,laser beam, ..) pump the crystal wich emite a certaine range of infrared wavelength sometime in visible range, this ...
Tintin's user avatar
  • 1
0 votes
0 answers
92 views

All possible models to explain the hierarchy problem?

There is an interesting paper by Arkani-Hamed and collaborators (https://arxiv.org/abs/1607.06821) to address the hierarchy problem. There, they consider many possible models of fundamental particle ...
vengaq's user avatar
  • 2,462
1 vote
1 answer
89 views

Cosmological Constant Problem calculations involving energy densities

I am following Timo Weigand lecutre notes on QFT, on page 28, he breifly touches on the Cosmological Constant Problem. But I am a little confused. He begins with a Lagrangian and include a nonzero $V_{...
VVM's user avatar
  • 489
1 vote
0 answers
41 views

Perturbative calculation of hierarchy problem

I've been trying to understand the origin of the hierarchy problem for the Higgs mass but I've tied myself into some pretty nasty knots and I'm hoping someone can shed some light on this. So as I see ...
J_P's user avatar
  • 233
3 votes
0 answers
84 views

Is the Higgs VEV unnatural?

Is there some way to argue that the Higgs VEV is unnatural, without even bringing up the Higgs boson mass? For example, can one show that the Higgs vev receives large corrections from new physics? The ...
Mitchell Porter's user avatar
0 votes
0 answers
105 views

The "survival hypothesis" and supersymmetry

Tidying up my old papers I came across my supersymmetry notes from the late 80s. I thought I'd reread them. They may be out of date now. I find the mathematics somewhat comprehensible but not the ...
Dan Piponi's user avatar
  • 2,188
1 vote
1 answer
41 views

Occurrence of *critical* damping

I am trying to understand the origin of some transient signals the vast majority of which have shape $(t/\tau) \exp(-t/\tau)$ for $t\gt 0$. This is notoriously the impulse response of a critically ...
Stefano Vitale's user avatar
0 votes
0 answers
100 views

Is fundamentally, gravity being much weaker than electromagnetism a myth? [duplicate]

I came across these two, conflicting conclusions information sources comparing at the quantum-scale distances (e.g. distance between two protons) the strength of Gravity Vs. Electromagnetism. I ...
Markoul11's user avatar
  • 4,170
1 vote
1 answer
133 views

Strong $CP$ problem and fine tuning

I have worked my way up to and through Srednicki's Quantum Field Theory chapter 94 and was also doing some reading on the internet about the strong $CP$ problem. Wikipedia's entry on the strong $CP$ ...
Cory's user avatar
  • 143
1 vote
0 answers
43 views

Can the low Higgs mass solve the problem of fine tuning of the Fermi constant?

The Standard Model indicates that quantum corrections to the Fermi constant make its value surprisingly large, and that its value could be closer to the Newtonian constant of gravitation unless there ...
AhMeD's user avatar
  • 31
-1 votes
2 answers
308 views

Why would the ratio of the strong nuclear force to electromagnetism be about 137 to 1? What does the fine structure constant have to do with it? [closed]

Is it just another weird coincidence that the strong force is approximately 137 times as strong (at appropriate distances) as the EM force? Also, when comparing the four fundamental forces and their ...
Kurt Hikes's user avatar
  • 4,509
1 vote
1 answer
49 views

When tweaking values of physic's fundamental constants, how are outcomes observed?

I often read about the concept of the "Fine-Tuned Universe". From my understanding, the universe's existence is sensitive to the values of certain fundamental physical constants, which are ...
Aaron Ullal's user avatar
2 votes
0 answers
162 views

Yet another 'dimensional regularization vs. the Hierarchy Problem' one

My current point of view regarding the Hierarchy Problem is of agreement with Michael's answer in this question. Or, in the words of Manohar in his Introduction to EFT notes, using a cutoff regulator ...
GaloisFan's user avatar
  • 1,742
3 votes
0 answers
74 views

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 ...
sooggzz's user avatar
  • 31
1 vote
1 answer
302 views

Hierarchy Problem and SUSY: Quantum Loop Corrections

One of the reasons SUSY was developed in the 1970s is to solve the mass hierarchy problem with the Higgs, according to which the mass of the Higgs is "unnatural" (cf. https://arxiv.org/abs/...
Anonymous5638's user avatar
1 vote
0 answers
167 views

Why is naturalness a problem?

I'm studying naturalness in the context of the Renormalization Group, and I don't understand why one talks about the "problem" of (lack of) naturalness. From what I understand the RG tells ...
Mauro Giliberti's user avatar
1 vote
2 answers
472 views

Probability of the cosmological constant having its value - how to understand this idea?

I'm reading this post: Definition of Fine-Tuning and John Rennie's answer that we can calculate the probability that the cosmological constant has its observed value (the answer being around 1 in $10^{...
Ameet Sharma's user avatar
  • 1,224
2 votes
1 answer
79 views

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 ...
7 votes
1 answer
766 views

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 ...
tomdodd4598's user avatar
0 votes
1 answer
157 views

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 ...
user1013388's user avatar
4 votes
0 answers
156 views

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_\...
xpsf's user avatar
  • 1,044
1 vote
1 answer
240 views

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 ...
Mauro Giliberti's user avatar
0 votes
1 answer
379 views

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 ...
Phanixman's user avatar
  • 175
2 votes
1 answer
262 views

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 ...
Jackson Burzynski's user avatar
4 votes
4 answers
757 views

Why is the flatness problem a problem?

Friedmann equation states $$ H^2 \equiv \left( \frac{\dot{a}}{a} \right) = \frac{8\pi G \rho}{3} - \frac{k}{a^2} $$ which describes the evolution of the expansion of the universe. Writing $\Omega(t)...
Johannes's user avatar
0 votes
0 answers
106 views

Does Supersymmetry really assures that the Higgs self-energy contributions cancel out?

The well-known "Supersymmetry Primer" from Stephen Martin explains in his introduction that for the cancellation of the Higgs self-energy diagrams (Fig. 1.1 a + b) generated by fermions and their ...
Frederic Thomas's user avatar
0 votes
2 answers
119 views

How do we know that the universe is really fine-tuned? [duplicate]

How physicists come to the conclusion that the cosmological constant and the other constants are really fine-tuned in a way that if they are changed just a bit, then stars and life won't exist?
Kokos98c's user avatar
6 votes
1 answer
189 views

Does our failure to detect neutrinoless double beta decay spell trouble for the seesaw mechanism?

The seesaw mechanism is a theoretical model of neutrino masses that has the side benefit of (arguably) naturally explaining why neutrinos are so much lighter than the other massive Standard Model ...
tparker's user avatar
  • 48.4k
-2 votes
1 answer
58 views

Are the twentyish constants that have to fall in-between certain ranges to make conditions for live to exist necessary? [closed]

I have been listening to an audiobook about what we cannot know (although I have heard about 20 constants somewhere before that, just can't recall where) and in chapter 9, author talks about twenty ...
Matas Vaitkevicius's user avatar
3 votes
0 answers
196 views

Why is technical naturalness a natural expectation?

In first few minutes of this lecture by Nathaniel Craig, he explains the idea of Dirac naturalness in the following way. Let us consider a QFT as an effective theory with a UV cut-off $\Lambda$. Let $...
SRS's user avatar
  • 26.8k
3 votes
1 answer
334 views

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 ...
Sayan Mandal's user avatar
0 votes
0 answers
33 views

Fine-tuning of the cosmological constant (reference request)

It has been claimed in various places on the internet and in books by non-physicists (i.e. by unqualified people) that if the cosmological constant $\Lambda$ had a value different by so much as $10^{-...
3 votes
0 answers
205 views

How Supersymmetry solves the hierarchy problem

The fermion contribution to the Higgs mass is $$\Delta m^2_{H}=-\frac{|\lambda_{f}|^2}{8\pi^2}\Lambda^2_{UV}+\dots$$ And the scalar contribution is: $$\Delta m^2_{H}=\frac{\lambda_{s}}{16\pi^2}\...
AWanderingMind's user avatar
19 votes
1 answer
3k views

What is the justification for Dirac's large numbers hypothesis?

Dirac stated that "Any two of the very large dimensionless numbers occuring in Nature are connected by a simple mathematical relation, in which the coefficients are of the order of magnitude unity." ...
AWanderingMind's user avatar
-2 votes
1 answer
113 views

How the hierarchy of forces is explained by Supersymmetry?

The hierarchy problem is often stated in two ways: First, the divergent corrections to the Higgs bare mass, second, why is gravity so much weaker than the other three forces. The solution to the ...
23rduser's user avatar
  • 468
2 votes
1 answer
541 views

Why is the smallness of Higgs mass not technically natural?

Technical naturalness The smallness of a parameter $\theta$ in the Lagrangian of a quantum field theory is said to be technically natural, if in the limit of vanishing $\theta$, the theory has some ...
SRS's user avatar
  • 26.8k
4 votes
3 answers
554 views

How is there no hierarchy problem without UV cutoff?

I can understand the quadratic divergent corrections to Higgs bare mass which is referred to as the hierarchy problem. But I don't understand how there won't be any hierarchy problem if we do not ...
23rduser's user avatar
  • 468
8 votes
2 answers
281 views

Does technical naturalness hold only for global symmetries, or also gauge symmetries?

Suppose you have an action $S(\epsilon) = S_1 + S_2 + \epsilon\, S_\mathrm{int}$. Assume that $S_1$ is gauge invariant under the action of the group $G$ and $S_2$ is gauge invariant under the action ...
Frank's user avatar
  • 91
9 votes
2 answers
305 views

What actually is the flatness problem?

One of the Friedman equations is given by $$ H^2\equiv\Big(\frac{\dot{a}}{a}\Big)^2=\frac{8\pi G}{3}\rho-\frac{k}{a^2},\tag{1} $$ which fixes the evolution of $a$ (with given $\rho(t)$) if values for $...
user2224350's user avatar
7 votes
3 answers
670 views

$\theta$ 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 ...
Michael Angelo's user avatar
1 vote
0 answers
158 views

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) ...
Michael Angelo's user avatar
11 votes
3 answers
719 views

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 ...
SRS's user avatar
  • 26.8k
7 votes
2 answers
2k views

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 ...
tuomas's user avatar
  • 484
4 votes
1 answer
400 views

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 ...
Samuel Hunter's user avatar
10 votes
4 answers
820 views

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 ...
Yly's user avatar
  • 3,693
2 votes
1 answer
64 views

What happens to the massive gauge bosons in a simple Little Higgs model?

I'm trying to understand a simple Little Higgs (toy) model where the Higgs doublet is made of pseudo Nambu-Goldstone Bosons generated by breaking the symmetry from $SU(3)_L\times U(1)_Y$ to $SU(2)_L\...
Joshua's user avatar
  • 1,373
1 vote
0 answers
61 views

Bound on large extra dimensions using gravitational waves

Are there proposed observations using gravitational waves which put a bound on the size of large extra dimensions (say in the context of ADD model)? The claim in the ADD paper is that you cannot ...
Bruce Lee's user avatar
  • 5,257