A model of the basic particles and forces featuring six quarks, three charged leptons, three massless neutral leptons and four fundamental force carrying bosons. The twelve fermions are arranged into three generations, while the bosons serve to explain the electromagnetic interaction plus the strong ...

learn more… | top users | synonyms

3
votes
2answers
1k views

Are quarks and leptons actually fundamental particles? [duplicate]

Possible Duplicate: What are quarks made of? Are quarks and leptons actually fundamental, or are they made up of even more fundamental particles? And is it true that many consider quarks ...
3
votes
1answer
423 views

Why does the Higgs field only couple to opposite-chiralities fermions?

According to the Wikipedia page on the Standard Model, the Higgs field interact with fermions through a Yukawa interaction coupling only left to right chiralities. What is the reason for that? Is that ...
-1
votes
1answer
213 views

Is the Standard Model experimentally verified? [closed]

Has the Standard Model of Particle Physics been experimentally verified? Or is it still waiting for experimental verification? OR, What aspects/predictions of the Standard Model have been ...
1
vote
1answer
106 views

What lepton neutrino would be in this reaction?

If I have a reaction (shown below), and I'm supposed to work out what the products will be, what would the lepton neutrino $\nu$ be? e.g electron neutrino: $$ \nu + p \to $$
11
votes
3answers
1k views

Hypercharge for $U(1)$ in $SU(2)\times U(1)$ model

I understand that the fundamental representation of $U(1)$ amounts to a multiplication by a phase factor, e.g. EM. I thought that when it is extended to higher dimensional representations, it would ...
6
votes
1answer
454 views

Is there a concise-but-thorough statement of the Standard Model?

I’m a grad student in high-energy physics. I’m familiar enough with the Standard Model, but I’ve always wondered whether there existed a canonical statement of, effectively, “what we talk about when ...
10
votes
1answer
67 views

N=2 SSM without a Higgs

In arXiv:1012.5099, section III, the authors describe a supersymmetric extension to the standard model in which there is no Higgs sector at all, in the conventional sense. The up-type Higgs is a ...
2
votes
1answer
202 views

Do neutrinos 'become' other types of particles between oscillations?

In light of the recent kurfuffle of FTL neutrinos I wonder, do neutrinos 'become' other particles between their oscillations between the different flavors of neutrino? I'm slightly familiar with ...
0
votes
0answers
88 views

Masses of all the particles in the Standard Theory [duplicate]

Possible Duplicate: If photons have no mass, how can they have momentum? I'm sure this question has been asked here before but I wasn't able to find it clearly answered in one q/a session. ...
15
votes
2answers
684 views

Is there some explanation for $y_t=1$

The Yukawa coupling of the top quark is Dirac-natural in a too excellent way, it is within one sigma experimentally, and within 99.5% in absolute value, of being equal to one. Without some symmetry, ...
10
votes
1answer
280 views

Technical naturalness of Yukawa couplings

Naturalness in the sense of 't Hooft tell us that a small parameter is a signal of a symmetry such that the parameter will be zero when the symmetry is exact. I am puzzled about how this principle is ...
10
votes
2answers
98 views

ATLAS Higgs Interpretation

I came across this abstract, and I am curious as to what the ATLAS Team has actually discovered: Abstract Motivated by the result of the Higgs boson candidates at LEP with a mass of about ...
4
votes
2answers
420 views

Quarks as preons for the whole standard model

This is a sequel to an earlier question about Alejandro Rivero's correspondence, the "super-bootstrap". The correspondence itself was introduced in his "Supersymmetry with composite bosons"; see the ...
7
votes
4answers
300 views

AQFT and the Standard Model

The German physicist Rudolf Haag presented a new approach to QFT that centralizes the role of an algebra of observables in his book "Local Quantum Physics". The mathematical objects known as operator ...
7
votes
3answers
1k views

Left and Right-handed fermions

Is there a simple intuitive way to understand the difference between left-handed and right-handed fermions (electrons say)? How to experimentally distinguish between them?
7
votes
2answers
212 views

Particles mass determined by SO(D-2) vs SO(D-1)

I've recently come across this statement that massless particles arise from $SO(D-2)$ symetry and massive particles from $SO(D-1)$. I would have guessed that it would be the exact opposite way, but ...
3
votes
0answers
107 views

How does one place QFT's reality in context with that of other areas of physics? [closed]

Okay, so I'm learning some QFT, I read through Bogoliubov, Shirkov Introduction to Quantized Fields up to the section on renormalization, and then wanted to see a more modern point of view- so I ...
4
votes
4answers
3k views

The Higgs field a new Luminiferous aether?

As of this writing it has been made clear to me that classical physics' Luminiferous aether was a terriblly poor discriptor of space. With the advent of Special Relativity and General Relativity, that ...
5
votes
1answer
244 views

Why are WW gg ττ branching ratios so similar for a 115 GeV SM Higgs?

In a previous question on Higgs branching ratios, I find this image (originally from page 15 here). I am VERY intrigued by the fact that decays to WW, gg, and ττ are almost equally probable, for ...
2
votes
2answers
279 views

Might the LHC see nothing new at all?

There's no guarantee that supersymmetry (or more exotic new physics) will be seen at the LHC. Meanwhile, it's standard lore that a Higgsless standard model becomes nonunitary somewhere in the vicinity ...
8
votes
1answer
467 views

Do color-neutral gluons exist?

If I'm correct a quark can change color by emitting a gluon. For example a blue up quark $u_b$ can change into a red up quark by emitting a gluon: $$u_b \longrightarrow u_r + g_{b\overline{r}}$$ ...
7
votes
1answer
212 views

Is there literature on a continuous mass spectrum for the Higgs field?

Various masses for the Higgs field are compatible with experiment, but is it possible that the Higgs field is not observable because it has a continuous mass spectrum? Work in the 60s and 70s on free ...
4
votes
2answers
418 views

Is the Higgs 3/4 detected already?

Can someone provide an expanded explanation on the statement that the Higgs field is already 3/4 detected? Link to ref (@nic, sorry I left it off, do a quick search on Higgs to find the right ...
1
vote
1answer
72 views

Fine tuning and parametric modelings

When I perform parametric modeling, if there is significant multicollinearity between variables I think should be independent, but in fact are not, I run into the case where one or more of the ...
0
votes
1answer
225 views

How is fine tuning of standard model conceptual different than the fine tuning of PI?

If I were to try to find pi using a ruler and a compass, I would first try to find out how many rational line segments of the diameter I could fit around the interior circumference and then continue ...
7
votes
0answers
163 views

Chiral fermions from torsion flux in M-theory?

Witten's 1981 paper "Search for a realistic Kaluza-Klein theory" is frequently cited for its observation that, in a compactification of d=11 supergravity on a manifold with SU(3) x SU(2) x U(1) ...
0
votes
0answers
188 views

Does the Standard model allow for radioactive decay prediction? [duplicate]

Possible Duplicate: Predicting Decay Rates via the Standard Model More specifically, does (any) current theory allow for approximate or exact predictions of atomic decay rates and types ...
3
votes
2answers
215 views

If dark matter is a new type of particle, what does that imply?

My understanding is that dark matter cannot be (or is at least highly unlikely to be) an exotic form of any known particle. On the other hand, articles about particle accelerators seem to say that the ...
4
votes
1answer
347 views

Detection of W and Z bosons

What specific behaviour confirmed the existence of the W and Z bosons at the UA1 and UA2 experiments? Thanks!
10
votes
4answers
454 views

strange modulation of radiactive decay rates with solar activity

Recently i found out this uber strange article about nuclear decay rates being somehow showing seasonal variations with a high correlation with sun activity. Two very precise questions: 1) has this ...
13
votes
2answers
985 views

115 GeV, 170 GeV, and the noncommutative standard model

Several years ago, noncommutative geometry was used to describe the standard model, somehow yielding a prediction of 170 GeV for the mass of the Higgs boson, a prediction which was falsified a few ...
7
votes
2answers
747 views

What is the difference between 'running' and 'current' quark mass?

When looking at the PDG, there is a difference between the 'running' and the 'current' quark masses. Does anyone know which is the difference between these two?
15
votes
2answers
2k views

Did the researchers at Fermilab find a fifth force?

Please consider the publication Invariant Mass Distribution of Jet Pairs Produced in Association with a W boson in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV by the CDF-Collaboration, ...
4
votes
2answers
498 views

Predicting Decay Rates via the Standard Model

Question 7584 illustrated a procedure to forecast the decay rates of isotopes with known long average lifetimes. Lifetimes of the many U isotopes vary from micoseconds to gigayears. F has only one ...
1
vote
2answers
370 views

Gravity and the Standard Model

Gravity is ignored in the SM. The proton rest mass is ~0.938 GeV/$c^2$. LHC protons will move with 7 TeV energy, presumably with a relativistic mass about 7,450 times rest mass. A cosmic ray with the ...
9
votes
4answers
1k views

Is there an accepted analogy/conceptual aid for the Higgs field?

Is there an accepted analogy / conceptual aid for the Higgs field? In Physics there are many accepted conceptual aids such as * Schrödinger's cat * Maxwell's Demon * I'm sure I'm missing ...
3
votes
1answer
229 views

Why should the mass of leptons to be near of proton and QCD/chiral scales?

The mistery of the mass of the top being in the electroweak scale can be justified by the Higgs mechanism itself; in some sense the top mass is the only "natural" mass, the other masses of fermions ...
5
votes
4answers
688 views

Why are neutrino oscillations considered to be “beyond the Standard Model”?

Is this just a historical artifact - that the particle physics community decided at some point to call all of the pre-oscillation physics by the name the "Standard Model"? The reason I ask is because ...
10
votes
1answer
1k views

What are the alternatives to the Higgs mechanism?

Can someone summarize, with references if possible, all of the alternatives to the simplest model (that requires only a single scalar Higgs field with the Mexican Hat potential) of spontaneous ...
13
votes
4answers
1k views

What is the need for the Higgs mechanism and electroweak unification?

The Higgs mechanism allows massless fields to acquire mass through their coupling to a scalar field. But if the masses cannot be predicted because the couplings have to be fixed, what really is the ...
17
votes
5answers
3k views

Are W & Z bosons virtual or not?

W and Z bosons are observed/discovered. But as force carrying bosons they should be virtual particles, unobservable? And also they require to have mass, but if they are virtual they may be off-shell, ...
7
votes
3answers
930 views

Other possible theories (other than string theory) which are generalizations of the standard model with incorporation of gravity

The only finite mathematical framework that incorporates both the standard model of particle physics and gravity under one umbrella that I am aware of is string theory. I would like to know whether ...
15
votes
6answers
2k views

Why should the Standard Model be renormalizable?

Effective theories like Little Higgs models or Nambu-Jona-Lasinio model are non-renormalizable and there is no problem with it, since an effective theory does not need to be renormalizable. These ...
10
votes
2answers
2k views

Shape of the Higgs branching ratio to ZZ

I've been looking at the, now very popular, graph of the SM Higgs decay branching ratios: You see that the ZZ branching ratio has a funny dip around the $170\, GeV$, very different from the WW ...
1
vote
2answers
283 views

Is there a relationship between Berry-Pancharatnam phase and CP violation in quark mixing?

Berry-Pancharatnam phase is the phase that quantum systems exhibit when they pass through a sequence of states and return to their original state. It's a complex phase and it is different from the ...
8
votes
2answers
562 views

Why do leptons and quarks mix?

Is the fact that weak eigenstates are not mass eigenstates completely arbitrary? Or is there a deeper reason for the existence of the PMNS and CKM matrices?
5
votes
2answers
531 views

“Space” in General Relativity and “vacuum” in Standard Model, is it the same thing?

And expansion of space is equal to expansion of vacuum?
16
votes
7answers
1k views

What Do We Get From Having Higher Generations of Particles?

Background: I have written a pop-science book explaining quantum mechanics through imaginary conversations with my dog-- the dog serves as a sort of reader surrogate, popping in occasionally to ask ...
38
votes
5answers
3k views

Why do we think there are only three generations of fundamental particles?

In the standard model of particle physics, there are three generations of quarks (up/down, strange/charm, and top/bottom), along with three generations of leptons (electron, muon, and tau). All of ...
4
votes
1answer
969 views

Why are there 3 quarks in proton?

A few quark related questions (I don't knowmuch about them other than there are 2 flavours concerning protons and neutrons) Why are there 3 quarks in a proton or neutron? Why not 2 or 4? Is there an ...