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 ...
9
votes
1answer
96 views
Is the fine-structure constant a parameter of the standard model?
According to the wikipedia entry on the fine-structure constant:
In fact, α is one of the about 20 empirical parameters in the Standard Model of particle physics, whose value is not determined ...
2
votes
0answers
45 views
Estimating the Kolmogorov Complexity of the Standard Model
The Kolmogorov complexity of a hypothesis / theory / model is the shortest computer program that simulates it, regardless of how inefficient executing that program may be in terms of memory and time. ...
1
vote
2answers
86 views
The status of $SU(3)_C$ symmetry in the Standard Model
In the Standard Model of Particle physics the $SU(2)_{EW}$ symmetry and the $SU(2)$ isospin symmetry are broken. What about $SU(3)_C$? Is it broken too?
if YES, what breaks the symmetry?
If NO, what ...
3
votes
0answers
49 views
List of cross sections?
Sometimes I need to look up a certain cross section, say the inclusive Z production cross section at $\sqrt{s}$ = 7 TeV. Is there a place where 'all the' cross sections are tabulated ...
5
votes
2answers
78 views
What constant varies in the fine structure constant?
Using the renormalization group approach, coupling constants are "running". If we apply this to the fine structure (coupling) constant, we do know that, e.g., at energies around the Z mass, $$\alpha ...
9
votes
0answers
87 views
infrared free QED and Higgsless standard model phenomenology
This is one of those "what if" fantasy world type questions. I like hard sci-fi so please no "well, you changed one thing about the world so now anything goes." :)
What if the Higgs had no vev?
That ...
4
votes
2answers
211 views
What is the Standard Model equation which unified Strong, Weak, and Electromagnetism?
I always heard that three atomic force in small scale structure (Strong, weak and electromagnetic) are unified through the standard model, but I've never seen its unified equation. What is single ...
6
votes
1answer
158 views
A Game Of The Number Of Space-Time Dimensions
Holger Bech Nielsen, one of the founders of string theory, has apparently just played some sort of game between different potential dimensions for space-time and reached the conclusion that D4 wins in ...
2
votes
1answer
81 views
How to find the Higgs coupling with a mixing matrix?
It is known that the couplings to the Higgs are proportional to the mass for fermions;
$$g_{hff}=\frac{M_f}{v}$$
where $v$ is the VEV of the Higgs field. I'm trying to figure out why this is true ...
4
votes
3answers
132 views
How quark electric charge directly have been measured?
How quarks electric charge directly have been measured when quarks never directly observed in isolation? (Due to a phenomenon known as color confinement.)
4
votes
1answer
39 views
Higgs VEV in terms of measurements on an ensemble?
Let $A$ be a Hermitian operator corresponding to some observable. If we prepare $N$ identical systems in the state $\psi$ and measure this observable in each system, the average of the measurements ...
1
vote
0answers
91 views
Mirror Matter Hypothesis?
What is the current state of the hypothesis of mirror matter today?
Are there any experimental data or theoretical arguments that exclude it by now, or is it still considered viable among physicists?
...
3
votes
1answer
165 views
What breaks the symmetry between the electromagnetic and weak nuclear force?
I know the electromagnetic force is mediated by a photon and the weak nuclear force is mediated by two massive bosons. Are there any other insights into why the masses are so different?
1
vote
1answer
116 views
Does the Higgs mechanism address the spin statistics problem?
Since the Higgs mechanism is so intimately tied to binding together massless chiral fermions, does it happen to have anything to say about the spin statistics issue?
I'm actually assuming the answer ...
3
votes
2answers
125 views
Do any good theories exist on why the weak interaction is so profoundly chiral?
I find the profound asymmetry in the sensitivity of left and right chiral particles to be one of the most remarkable analytical observations captured in the Standard Model. Yet for some, I've not ...
3
votes
1answer
140 views
Origin of electric charge
Baryons have charges that are the result of a polynomial calculation of their building blocks (quarks)'s fractional charges. But what gives these quarks electric charges? What interactions do they ...
5
votes
0answers
52 views
Does the Standard Model plasma develop a spontaneous magnetisation at finite temperature?
Reference: arXiv:1204.3604v1 [hep-ph] Long-range magnetic fields in the ground state of the Standard Model plasma.
Alexey Boyarsky, Oleg Ruchayskiy, Mikhail Shaposhnikov.
The authors of this paper ...
2
votes
0answers
31 views
Literature value of forward-backward asymmetry on the Z resonance?
I did a Standard Model calculation and I want to compare my answer to a measured value.
Does anyone know the literature value for the forward-backward asymmetry $\frac{\sigma_F - \sigma_B}{\sigma_F + ...
0
votes
0answers
98 views
Weak isospin and types of weak charge
My understanding is that QCD has three color charges that are conserved as a result of global SU(3) invariance. What about SU(2) weak? Does it have two types of charges? What I'm getting at is:
U(1) ...
5
votes
2answers
114 views
Why is there a linear relationship between charge and isospin?
So the title basically says it all. Something that's really bothering me is the fact that the Gell-Mann Nishijima relationship can be extended to provide a linear relationship between charge and all ...
2
votes
1answer
72 views
Is energy always proportional to frequency?
Google has no results found for "energy not proportional to frequency" and many results for E=hf. Is there an example of an energy that is not proportional to frequency?
3
votes
0answers
54 views
How many orders of magnitude in energy spans the domain of validity of the Standard Model?
I am wondering if it makes sense to state that the upper limit is roughly 1012 eV (up to know the physics probed by the LHC seems to be pretty consistent with the SM) and the lower one is ... the ...
15
votes
3answers
488 views
Why is gravity so hard to unify with the other 3 fundamental forces?
Electricity and magnetism was unified in the 19th century, and unification of electromagnetism with the weak force followed suit, bringing into play the electroweak force.
I've been told that ...
4
votes
0answers
95 views
Does the Standard Model have a Landau pole?
I have seen the statement that the Standard Model has a Landau pole, or at least it its believed that it does at $\sim 10^{34}$ GeV. Has this actually been proven (at least in perturbation theory, as ...
3
votes
3answers
73 views
Trilinear gauge couplings: Spin
In non-abelian gauge theories self interaction of gauge fields is permitted, allowing coupling such as $WWZ$ (i.e. $Z$-boson decaying to $W^+W^-$) or ggg (i.e. gluon splitting into two new gluons).
...
0
votes
0answers
62 views
Pareto efficiency and Standard Model parameters
Pareto Efficiency is a well understood concept in economics, which basically is a condition where no one actor could be made better off without some one being made worse off. This condition allows ...
1
vote
2answers
107 views
What is mass of free up and down Quark?
Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks ...
5
votes
0answers
113 views
Are QFT solitons expected to represent standard model particles? Or strings?
Is work on solitons in QFT's focused on finding solutions that could represent the fundamental particles of the Standard Model, or is the work focused on finding particles Beyond The Standard Model? ...
0
votes
1answer
117 views
why drag cause mass in higgs field ? how could drag cause mass?
why in higgs field drag cause mass?
drag is force in general not mass
Higgs field- Inquiring Minds - Questions About Physics
how drag of higgs field cause mass?
2
votes
0answers
114 views
Do all the particles acquire mass in the Standard Model due to the Higgs mechanism only?
I know that a mass term for an intermediate boson is not compatible with the gauge symmetry. But in principle a mass term for the electron field does not violate a gauge symmetry. However to build an ...
0
votes
1answer
56 views
Does it happen at high energies (heavier leptons decay)?
A lepton is an elementary particle. The best known of all leptons is the electron which governs nearly all of chemistry as it is found in atoms and is directly tied to all chemical properties.
The ...
0
votes
0answers
17 views
Hamiltonian of the charged current in SM (related to the lorentz invariance)
recently when I was studying the scatterings which involves a vector boson (like W boson) as an intermediate particle, I saw that the propagator is not Lorentz invariant, I read that there is another ...
0
votes
3answers
158 views
The Role of Gravity among the Fundamental Forces of Nature
If we look at the standard model, we have 4 fundamental forces which include
Gravity,
Electromagnetism,
Nuclear weak force,
Nuclear strong force.
I would like to look at Gravity for a minute. ...
4
votes
2answers
223 views
Is there some sort of Pati-Salam model with mixed generations?
The evidence for an approximate "lepton as fourth colour" symmetry is so overhelming in the particle spectrum that Hanlon's razor does not seem to apply. Still, my own incompetence fails to recognise ...
6
votes
1answer
136 views
What is the origin of flavor? [duplicate]
Possible Duplicate:
Origin of lepton/quark generations?
In the standard model (and in nature), Fermions appear in different generations, or flavors. Besides up and down quarks and ...
6
votes
3answers
189 views
Origin of lepton/quark generations?
What theoretical explanations exist for the fact that there are three generations of leptons and quarks?
I'm not so much asking why there are exactly 3 generations, but rather what makes electron, ...
-1
votes
1answer
109 views
How quarks converted into leptons
Since the charged pions decay into two particles, a muon and a muon neutrino, seems quarks disappeared!,
The decay proceeds by the weak interaction $W^{+}$ and can be visualized in terms of Feynman ...
2
votes
2answers
108 views
What is difference between the different 'flavours' of neutrinos?
Moreover, how-come scientist know that muon-neutrino are different from electron-neutrino when they didn't even know what the difference was? Did they interact differently with other particles?
4
votes
2answers
222 views
About free quarks and confinement
I simply know that a single free quark does not exist. What is the reason that we can not get a free quark?
If we can't get a free quark then what is single-top-quark?
5
votes
2answers
96 views
What maintains quark spin alignments in baryons?
What maintains quark spin alignments in baryons?
The $uud$ proton and $udd$ neutron are both spin 1/2, implying that two of their spin 1/2 quarks are always parallel and the other is always opposed.
...
1
vote
2answers
179 views
What is the expectation value of the number operator when the vacuum has a VEV?
The number operator N applied to a field whose vacuum has zero VEV gives $N|0>=0$. What if we apply it to the Higgs field?
The background of this question is that in popular scientific accounts, ...
3
votes
1answer
223 views
Higgs boson in LHC
Recently,the higgs bosons are discovered in LHC. My question is
How did they come to know that the particle that are created are actually Higgs boson?
On the basis of which properties,they ...
2
votes
1answer
113 views
How exactly are the different motions of only one kind of fundamental string assumed to give rise to the spectrum of elementary particles we observe?
In string theory, it is assumed that all particles can be described as quanta corresponding to the excitations of only one kind of fundamental string.
How can in principle the different motion ...
3
votes
1answer
250 views
Feynman rules for SUSY
This might be an incredibly naive question, but I'm wondering if there are a set of rules for "translating" between Standard Model and SUSY. For instance, if I want want to go from a Standard Model ...
3
votes
2answers
104 views
Playground of Forces
Why is it that the gravitational force acts on large sized objects while the strong and weak nuclear forces act at subatomic levels only? What is that stops each other to enter each others domain?
3
votes
2answers
139 views
Simulating a proton
How much computing power would it take to simulate a single proton from the bottom up, without taking any shortcuts whatsoever?
My current understanding is that:
A proton is basically a seething ...
9
votes
1answer
276 views
The physics community's take on noncommutative geometry
Connes's noncommutative geometry program includes an approach to the Standard Model that employs a noncommutative extension of Riemannian metric. In recent years I've heard physicists say that this ...
10
votes
1answer
287 views
What does the latest $B_s^0\rightarrow \mu^+\mu^-$ results mean for SUSY?
A paper from the LHCb collaboration just came out last week, stating basically that the $B_s^0\rightarrow\mu^+\mu^-$ decay matches standard model predictions, and people are already shouting that SUSY ...
3
votes
1answer
280 views
Why is mass renormalization insufficient to explain electron mass?
In the Standard Model, I understand that the mass of the electron is assume to arise from two effects:
A bare mass given by Yukawa interaction with the Higgs field, and
A mass correction from mass ...
2
votes
4answers
163 views
Computer Science Modeling of Physical World
I am curious what efforts have been made to date to define virtual computer worlds based on the physics we know in the real world?
I think it would be awesome to say start off with an atom defining ...
