Exploring the Possibility of No GUT and Unification in the Three Forces

In summary: However, if they are related to the GUT scale, then they would most likely have a much higher mass and thus not contribute to the hierarchy problem at lower scales. In summary, the existence of a Grand Unified Theory (GUT) and unification of the three fundamental forces is still uncertain because experiments have not been conducted at the GUT scale. However, many in the physics community believe that there is a deeper theory beyond the Standard Model that explains its structure, even if it may never be fully understood. The search for new particles, such as the 750 GeV scalar, could provide clues to this deeper theory, but its existence does not necessarily imply a GUT. If a GUT is found, it would have additional Higgs
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  • #2
kodama said:
is it possible there is no GUT and no unification of the 3 forces?
Of course this is possible. Nobody has made experiments at the GUT scale (or would-be GUT scale) and so we cannot say with certainty how physics at that scale behaves. All we can say is how our current physics would behave if extrapolated to a certain scale, but without actually performing experiments, there is no way of being certain that this is actually the case.
 
  • #3
kodama said:
is it possible there is no GUT and no unification of the 3 forces?

In the narrow sense, surely. Nothing critical to the existence of the universe requires gauge coupling constant unification, although it would be awesome if it existed, and there doesn't have to be a GUT in the narrow sense of the term that refers to a single Lie group that corresponds to all particles that exist and none that don't and from which the interactions of fundamental physics can be inferred.

In the broader sense of the term "GUT" to refer to some deeper theory that explains from first principles why the Standard Model has the particles and physical constants that it does, however, I think it is hard to deny that almost everyone in the field thinks that this deeper theory to explain the Standard Model exists, even if we may never master it. There is too much of a semblance of order in the structure of the Standard Model for it itself to be the fundamental laws of Nature without further logic mandating it, even if everything that is implied by the deeper theory can be summed up in the Standard Model plus some sort of quantum gravity theory.
 
  • #4
with GUT there are additional higgs. any prospect LHC will find them, perhaps 750 GEV?
 
  • #5
The scalars related to the GUT scale will not be found at 750 GeV. A 750 GeV scalar would be more likely to be related to various SUSY models or other two-higgs doublet models. Of course, those can be embedded within a GUT, but in itself I would not take the 750 GeV scalar (if confirmed) as a direct sign of grand unification.
 
  • #6
so what would be scalar massses for non-SUSY GUT's. does MSSM presuppose a GUT like SO(10)?
 
  • #7
Scalar masses related to the GUT scale (SUSY as well as non-SUSY) would be at some ##10^{15}## GeV or so. A SUSY model does not necessarily have an underlying GUT, but many GUT models build upon having SUSY, although it is generally not a requirement.
 
  • #8
do you have any preference for GUT, such as SO(10)?
 
  • #9
Yes, I would prefer there to be something unexpected at a lower scale. It would make physics much more interesting than an assumed high energy GUT which will not be tested in my lifetime.
 
  • #10
Orodruin said:
Yes, I would prefer there to be something unexpected at a lower scale. It would make physics much more interesting than an assumed high energy GUT which will not be tested in my lifetime.

are there any examples of serious proposals, or are you thinking SUSY/MSSM?
 
  • #11
There are several ideas floating around, but one of those would be equally boring. The interesting part comes if there is a mystery in need of a new type of explanation.
 
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  • #12
i know proton lifetime has ruled out SU(5), what are the prospects for SO(10)?
 
  • #13
kodama said:
with GUT there are additional higgs. any prospect LHC will find them, perhaps 750 GEV?

The 750 GeV bump at the LHC, if it is real (and honestly, I am increasingly inclined to think that it is just a fluke or experimental error despite the fact that this experimental data point has already garnered 750 preprints), is very un-Higgs-like, because while it has the characteristic diphoton decay of a Higgs boson, it does not have any of the other associated decays which would be visible at the LHC if it were Higgs-like.
 
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  • #14
Orodruin said:
Scalar masses related to the GUT scale (SUSY as well as non-SUSY) would be at some ##10^{15}## GeV or so. A SUSY model does not necessarily have an underlying GUT, but many GUT models build upon having SUSY, although it is generally not a requirement.

do those GUT higgs like scalars also have a hierarchy problem ?
 
  • #15
kodama said:
do those GUT higgs like scalars also have a hierarchy problem ?
They very likely would if you found them at 750 GeV.
 

Related to Exploring the Possibility of No GUT and Unification in the Three Forces

1. What are GUTs and unification?

GUTs (Grand Unified Theories) are theoretical frameworks that aim to unify the three fundamental forces of nature - the strong nuclear force, the weak nuclear force, and electromagnetism - into a single, unified force. Unification, in this context, refers to the idea of finding a single, fundamental theory that can explain all of the known physical phenomena in the universe.

2. Why is unification important in science?

Unification is important because it provides a deeper understanding of the physical laws that govern our universe. It also allows for a more elegant and simplified explanation of the complexities of nature. Additionally, unification can lead to new predictions and discoveries, which can further our knowledge and potentially lead to technological advancements.

3. How do scientists attempt to unify the fundamental forces?

Scientists use mathematical equations and theoretical models to try and find commonalities between the fundamental forces. They also conduct experiments, such as colliding particles at high energies, to test these theories and gather evidence for unification.

4. What challenges do scientists face in achieving unification?

One of the main challenges in achieving unification is the difficulty in testing these theories. Many GUTs require energies that are currently unattainable with our current technology. Additionally, there may be unknown or unaccounted for phenomena that could potentially disprove these theories.

5. Has unification been achieved in any aspect of physics?

Currently, unification has only been achieved in certain areas of physics, such as the unification of electric and magnetic forces into the electromagnetic force. However, there is still much debate and research being done in the pursuit of a complete and comprehensive theory of everything.

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