Questions tagged [grand-unification]

A Grand Unified Theory is a model in particle physics in which at ultra-high energy, the 3 gauge interactions of the Standard Model (electromagnetic, weak, and strong) merge into a single one, characterized by one larger encompassing gauge symmetry and one unified coupling constant. After SSBreaking, force carriers differentiate themselves and are driven by the RG to their values and numbers in the lab. Use for gauge GUT and gravity unification.

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What does it mean, during the Grand Unified Epoch, that matter fluctuated between lepton and baryon states?

My understanding of leptons and baryons is that leptons are an elementary particle, while baryons are a composite particle. Can someone explain to me what particles fluctuating between lepton and ...
blacktopshaman's user avatar
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$SU(5)$ Gauge Field Theory, symmetry breaking

If I start with an $SU(5)$ gauge group and discover that the vacuum is preserved only by matrices of the form $G$ $$\begin{bmatrix} A & 0 \\ 0 & B \\ \end{bmatrix}$$ where ...
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Charged particles deflected by gravitational and magnetic fields

I am trying to better understand one of my previous questions, and another. Charged particle in uniform Magnetic field Does a charged particle orbiting Earth radiate? https://en.wikipedia.org/wiki/...
Zoltan K.'s user avatar
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Does the standard model predict $\alpha_G^{-1}\approx c_5$ for $m_{proton}$? [closed]

Given $$\alpha_G^{-1} = \frac{m_{planck}^2}{m_{particle\ of\ interest}^2}$$ $$particle\ of\ interest = proton$$ $$c_5 = fifth\ Catalan\ Mersenne\ prime = 2^{(2^{(2^{(2^2-1)}-1)}-1)}-1$$ Does the ...
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(Anti-)Fundamental Representation of $SU(5)$ GUT

In many places, it has been mentioned that the sum of electrical charges of the particles present in $\overline{5}$ of $SU(5)$ is zero since the trace of $SU(5)$ generators is zero. I do not ...
Alex's user avatar
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Is there a clean mathematical way to deduce grand unification from string theory?

The question says it all. Simply stated: Can one prove grand unification from string theory? What is the argument chain of such a proof? The textbooks I read so far only appear to give hand-waving ...
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Was the Michelson & Morely experiment ever valid? [closed]

One of the key predecessors to Einstein's Relativity was another theory having to do with an "Aether" material. This substance was supposed to be the substrate that the universe is built ...
david.cowan's user avatar
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How are representations of fermions and bosons made for different gauge groups?

I have been told to that representations(for particle physics) go like this: How many versions or charges of a particle can be changed from a group's associated gauge interaction In the standard model ...
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Is Monopolium Theoretically Stable?

Monopolium is the hypothetical composite of either (1) a north-south pair of monopoles, or (2) a magnetic monopole that has captured an atomic nucleus, analogous to how atomic nuclei capture electrons....
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What kind of a space is $\mathbb{C}_{-1}$?

In the first paragraph on page 24 of this paper: https://arxiv.org/abs/0904.1556, it's written the left-handed leptons $\nu_L$ and $e^−_L$ both have hypercharge $Y=−1$, so each one spans a copy of $\...
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Doublet-triplet splitting in GUT: how can the "color triplet" have mass?

I'm hopelessly perplexed about the $SU(5)$ doublet-triplet splitting. I read that the color triplet part of the Higgs quintuplet needs to have extremely high mass compared to the "electroweak&...
SgtJohn74's user avatar
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Is $SU(N)$ with $N>5$ ruled out as a GUT?

Reading the "mainstream" sources, the candidates for GUT gauge groups are $SU(5)$, $SO(10)$ and $E_6$ Yet I understand for ranks 5 and 6, $SU(6)$ and $SU(7)$ also have complex ...
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Finite quotient of standard model group [closed]

In chapter three, p. 31, of this paper (https://arxiv.org/abs/0904.1556) Baez and Huerta show that the standard model's structure group contains, in a sense, superfluous parts. They show that one can ...
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What are the most promising contenders for a theory of everything/unified theory besides string theory? [closed]

Many of us are debating this question on youtube and twitter. Has string theory really failed? What are the conditions under which string theory could be validated or rejected/falsified?
DrBrianKeating's user avatar
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Inflation, dark energy and symmetry breaking

Aside as the inflaton has been hypothesized to have arisen from the breaking of the $SU(5)$ GUT symmetry, could dark energy have arisen as a weaker inflaton from electroweak symmetry breaking?
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Why is gluon massless from GUT point of view?

For not violating the gauge invarinace, of course, the gluon is massless. In respect of Spontaneous Symmetry breaking(SSB), however, I wonder why the gluon is massless, compared the $W^+$, $W^-$, $Z$ ...
Sasha Shin's user avatar
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Number of Goldstone modes when the symmetry is broken?

I am studying lecture notes on Groups and Representations by Prof. Andre Lukas. I am unable to completely understand notesnd the examples worked out in the symmetry-breaking application section (pages ...
CondensedChatter's user avatar
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Number of free parameters in $SU(5)$ GUT model

Lately, I have been studying the potential of scalar fields in this theory. In general, what is the point of this GUT if, there, more free parameters have been added? The standard Higgs potential in ...
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Hypercharge and photon definitions in $SU(5)$ GUT

So, a weak isospin and hypercharge in $SU(5)$ are defined as $$ T_3 = \frac{1}{2}diag(0,0,0,1,-1) $$ $$ Y = \sqrt{\frac{3}{5}}diag(-1/3,-1/3,-1/3,1/2,1/2) $$ The hypercharge already has the $\sqrt{3/5}...
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Resource Recommendation for Grand Unified Theory [duplicate]

Recently I have started studying grand unified theories. One department where I found myself lacking in group theory. Can anybody tell to what level group theory is needed to understand Grand unified ...
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Do $Y$ bosons gain a little bit of mass from Higgs of $\bf 5$ rep in $SU(5)$ GUT theory?

I know that when the Higgs in the 24 rep takes a v.e.v. of this form $$v_{24}\,\mathrm{diag}\begin{pmatrix} -\frac{2}{\sqrt{15}} & -\frac{2}{\sqrt{15}} & -\frac{2}{\sqrt{15}} & \frac{3}{\...
Peter's user avatar
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What causes running coupling constants to converge to one value at high energy?

In this article ("The coupling constants and unification of interactions", sicsmasterclasses.org) we can read: The running coupling constants. Scientists believe that as they push the ...
MatterGauge's user avatar
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GUT decomposition

How can we decompose a generic $SU(5)$ irreducible representation as a direct sum of irreducible $SU(3) \times SU(2) \times U(1)$ representations?
Tony Stack's user avatar
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In an $SO(10)$ GUT, how many gauge fields acquire masses that are above the electro-weak scale?

The $SO(10)$ group is spontaneously broken down into the Standard Model gauge group at around $10^{16}$ GeV and the electroweak scale is ~246 GeV. I think there should be 45 gauge fields predicted by ...
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2 votes
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Why must $U(1)$ matrices commute with $SU(2) \times SU(3)$ matrices in embedding within $SU(5)$?

I'm a physicist taking a groups course. I can believe that the direct sum of the fundmental representations for the $SU(2)$ and $SU(3)$ matrices will work as an embedding of the $SU(2) \times SU(3)$ ...
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Have magnetic monopoles been predicted to have been produced in other cases than those of symmetry breaking in GUTs?

Also, what other configurations are magnetic monopoles theorized to exist in? (such as black holes, monopole walls etc.)
Tim Hulland's user avatar
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Deduction of weak boson hypercharge in Georgi–Glashow $SU(5)$ grand unified theory (GUT)

In the Georgi–Glashow model, the extra 12 bosons $X_\mu^a$, $Y_\mu^a$ that appear have weak hypercharge $y = -\frac{5}{6}$. I want to know how this is deduced from the weak hypercharge generator $$Y = ...
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A question on the electrostrong force

I understand that the strong nuclear force is carried by gluons, the electromagnetic force is carried by photons and the weak nuclear force is carried by the $W$ and $Z$ bosons. However, in the ...
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By which interaction will proton decay? [duplicate]

I learned that proton takes at least $10^{34}$ years to decay. If it will decay one day, will it decay via weak interaction or some other interaction?
Dom Tesilbirth Shira's user avatar
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Gauge boson layout in $\rm SU(5)$ GUT unification

It is known that the theory of the Great Unification $\rm SU(5)$ GUT encapsulates the gauge groups of the standard model to one large group $\rm SU(5)$. But is it possible to show schematically how to ...
Peter's user avatar
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Would there be a force carrier particle in the unified field theory?

So from what I understand, each fundamental force (with the exception of gravity unless you count the hypothetical graviton) has a force carrier particle that mediates the force. Does that mean if the ...
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Tensor product of fundamental representation of $SU(5)$

In Srednicki's QFT book (see pg. 605) he writes that the fundamental representation of $SU(5)$ may be written as (97.2), $$ 5\to \left(3,1,-\frac{1}{3}\right)\otimes \left(1,2, +\frac{1}{2}\right).\...
MarcosMFlores's user avatar
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4 answers
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What particles are thought to have existed before Inflation?

What fundamental particles do most Grand Unified and Inflationary theories predict existed before the Inflationary period? Basically, what do we expect the family of particles existing during the ...
Anthony Khodanian's user avatar
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Name for 16⊕1͞6 bosons of E6 & larger GUTs?

E6 GUTs put fermions into $27→16_1⊕10_{-2}⊕1_4$ and gauge bosons into $78→45_0⊕16_{-3}⊕\overline{16}_{3}⊕1_0$. And larger GUTs (e.g. E8 on 𝕋⁶/ℤ₆×ℤ₂, E8 on 𝕋⁶/ℤ₃×ℤ₃) usually incorporate these. The $...
alexchandel's user avatar
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Are orbifolded 10d $E_8$ GUTs valid low-energy EQFTs of string theory? Or swampland?

AdAMP recently proposed a string-reminiscent $E_8$ GUT (digest, full) where 6 extra dimensions are compactified on a $\mathbb T^6/(\mathbb Z_3\times\mathbb Z_3)$ orbifold to yield the 4d Standard ...
alexchandel's user avatar
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10-dimensional and 15-dimensional matrix representations of $SU(5)$: explicit 24 Lie algebra generators

There are some previous discussions in this post Representation of the $\rm SU(5)$ model in GUT which confused me. So I want to follow up with a new question. It is easy to write down the 5-...
ann marie cœur's user avatar
5 votes
1 answer
330 views

What's the mathematical explanation of the emergence of magnetic monopoles during the early universe?

I would "simply" like to know the full mathematical explanation of: Why do these topological defects occur in the first place? And more importantly, Why must these defects/particles carry ...
Bobby Shmurda's user avatar
8 votes
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174 views

What is the status of orbifolded 10D E8 theory?

A recent series of papers (1, 2) presents an $E_8$ GUT in 10 dimensions, where compactification on a $\mathbb T^6/(\mathbb Z_3\times\mathbb Z_3)$ orbifold ($\mathbb T^6/(\mathbb Z_6\times\mathbb Z_2)$ ...
alexchandel's user avatar
4 votes
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Zee Chapter VII.5: Can the fermion $10$ be the composite of fermion $5^*$?

In Zee Chapter VII.5 QFT book: He showed that the standard model fermions form $5^*$ and $10$ representations of $SU(5)$: $$ 5^* \oplus 10. $$ In particular, the $10$ is the anti-symmetric matrix ...
ann marie cœur's user avatar
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Figure of $SO(10)$ grand unified theory in $E_6$ from Wikipedia

In this figure from Wikipedia, it shows that the representations of particles of $SO(10)$ grand unified theory, their patterns of charges for particles in the $SO(10)$ model, rotated to show the ...
ann marie cœur's user avatar
1 vote
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Figure of $SO(10)$ grand unified theory from Wikipedia

In this Figure from Wikipedia, it shows that the representations of particles of $SO(10)$ grand unified theory, representations as numbers labeled in several axes. Descriptions: The patterns of weak ...
ann marie cœur's user avatar
2 votes
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104 views

CERN LHCb leptoquarks and grand unified theory

Recent CERN LHCb experiment suggests possible leptoquarks as new particles beyond the standard model may be discovered, with 3.1 $\sigma$ not the 5 $\sigma$ discovery. What are the viable candidates ...
ann marie cœur's user avatar
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1 answer
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Would the recently suspected violation of Lepton universality in $B$ meson decays implicate that the Grand unification occurs at a lower energy scale?

Articles like https://physicsworld.com/a/has-a-new-particle-called-a-leptoquark-been-spotted-at-cern/ report on a difference in the $B$ meson decay chain in electrons to muons which amounts to now $3....
Frederic Thomas's user avatar
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How Can I Find Good Resources to Learn About the $SU(5)$ and $SO(10)$ Grand Unified Theories Without an Extensive Background in the Field?

I'm a first-year university student. My group and I have been tasked with finding out whether, given current scientific consensus, it looks like a viable Grand Unified Theory (GUT) can be found. We ...
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1 answer
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Does a grand unified field theory need to include a Dark Energy field? [closed]

Nobody has unified field theories yet but could dark energy if considered as a field be useful in this endeavour?
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Error in Wikipedia on a flipped $SO(10)$ model

In the description of Wikipedia of flipped SO(10) model, it says that: In flipped $SO(10)$ models, however, the gauge group is $[SO(10)_F × U(1)_B]/Z_4$. If we suppose $[SU (5) × U(1)_χ ]/ Z_5$ ...
ann marie cœur's user avatar
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Disadvantages of flipped $SU(5)$ model

Question: What are the advantages and disadvantages of flipped $SU(5)$ model? We know the fermions (same form for three families), each consisting of the representations $\overline{5}_{−3}$ for the ...
ann marie cœur's user avatar
4 votes
1 answer
276 views

Does the lack of evidence for proton decay really rule out the basic grand unification theories?

Grand unification theories (GUT), such as $SU(5)$/$SO(10)$/SUSY variants, suggest proton decay. The lack of observational evidence for proton decay is supposed to rule out basic GUTs, at least for the ...
MadMax's user avatar
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$\text{SU}(5)$ GUT Higgs sector and symmetry breaking

The Higgs sector of minimal $\text{SU}(5)$ GUT consists of scalar fields in two representations, a $\mathbf{24}$ and a $\mathbf{5}$. All the $\mathbf{5}$ non-derivative terms form the potential $V(\...
Peter's user avatar
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3 votes
2 answers
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Proton decays in Pati-Salam model or Georgi-Glashow model

This Pati-Salam model doesn't predict gauge mediated proton decay, according to Wikipedia. However the Georgi-Glashow model predict gauge mediated proton decay, according to Wikipedia. I thought the ...
ann marie cœur's user avatar