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 ...
6
votes
3answers
415 views
How are the masses of unstable elementary particles measured?
I am interested in knowing how (Q1) the particle's masses are experimentally determined from accelerator observations.
What kind of particles? They must be as far as we know elementary and unstable ...
1
vote
4answers
826 views
Why is Neutron Heavier than Proton?
This is Neutron decay:
$$n^o \to p^+ + e^- + \overline {\nu_e}.$$
and this is proton one:
$$p^+ \to n^o + e^+ + \nu_e$$
so when the $e^+ =e^-$ and $\nu_e=\overline {\nu_e}$ why $n \not= p$?
my ...
10
votes
4answers
2k views
Why do electron and proton have the same but opposite electric charge?
What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of ...
2
votes
1answer
217 views
Higgs potential
The potential for the Higgs field is standard a quartic one (Mexican hat). Is this done for simplicity or are there fundamental reasons for this choice? I can imagine further contributions to this ...
1
vote
1answer
237 views
Why are all observable gauge theories not vector-like?
Why are all observable gauge theories not vector-like?
Will this imply that the electron and/or fermions do not have mass?
How is this issue resolved?
Background:
The Standard Model is a ...
4
votes
2answers
382 views
Is the Higgs a quantum field or a particle?
The Higgs is not detected in the asymptotic data, so it is possible that there is no particle interpretation for the Higgs quantum field. Indeed, the Higgs potential is only positive definite if the ...
0
votes
0answers
95 views
What would the universe be like if Electroweak symmetry were unbroken? [duplicate]
Possible Duplicate:
What happens to matter in a standard model with zero Higgs VEV?
What if the Higgs did not have a "Mexican hat" potential and the therefore it's vacuum expectation value ...
2
votes
2answers
263 views
Some very basic questions on the Higgs Boson
What exactly is a boson?
Is the Higgs boson the cause of gravity or a result of it? Does the collision of particles at the LHC create a gravity field or waves or somehow interact with the gravity ...
1
vote
1answer
117 views
Lepton masses in the Standard Model
Some simple questions regarding leptonic masses in the Standard Model (SM):
Why there is not an explicit mass term in addition to the effective mass term that arises from the Yukawa terms after ...
4
votes
0answers
110 views
Relation among anomaly, unitarity bound and renormalizability
There is something I'm not sure about that has come up in a comment to other question:
Why do we not have spin greater than 2?
It's a good question--- the violation of renormalizability is linked
...
1
vote
0answers
50 views
Is there mathematical proof of the vectorial character of the strong and em forces?
In a old paper,
http://arxiv.org/abs/hep-th/9509163
Becca Asquith argues that it is possible to prove that if the SU(2)xU(1) sector of the standard model is chiral, then the SU(3)xU(1) sector is ...
2
votes
2answers
98 views
Charges of quarks and leptons
Are there any theoretical restrictions within the framework of QFT that fix the relative sign between charged leptons and up-type quarks?
We know that in our universe, they have opposite signs -- ...
1
vote
1answer
288 views
Quark Radius Upper Bound
If quarks had internal structure (contradicting current beliefs), what is the lowest
upper bound on their "radius" based on current experimental results?
If possible, I'd prefer to only consider ...
4
votes
5answers
1k views
How does Higgs field relate to Aether theories?
I am an amateur learning about the Higgs because I was interested in what the LHC's purpose is.
I read that as a particle passes through space, it is actually passing through a Higgs field and there ...
6
votes
1answer
458 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?
2
votes
1answer
186 views
What is meant by the rest energy of non-composite particle?
When talking about the rest energy of a composite particle such as a proton, part of the rest energy is accounted for by the internal kinetic energy of its constituent quarks. But what is physically ...
3
votes
3answers
389 views
Does every elementary particle have its own separate field?
Higgs field is pretty simple for me to understand, you have one field that creates one particle (Higgs boson).
So I continue to assume one field one particle.
Up field creates a up quark.
Down field ...
3
votes
0answers
271 views
On the naturalness problem
I know that there are several questions about the naturalness (or hierarchy or fine-tunning) problem of scalars masses in physics.stackexcange.com, but I have not found answers to any of the following ...
4
votes
0answers
105 views
What is the rate of B violation expected in the standard model during high energy collisions?
In a recent question Can colliders detect B violation? I asked about detecting B violation in collisions. Here I am interested in the theory aspect. (I asked both questions originally in the same ...
5
votes
2answers
228 views
How does Annihilation work?
I'm wondering why matter and antimatter actually annihilates if they come into contact. What exactly happens? Is that a known process? Is it just because of their different charges? Then what about ...
4
votes
2answers
407 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 ...
4
votes
2answers
179 views
What has been measured at the Higgs experiment and what do we know now?
Explained at the level of a 5$^{\text {th}}$ semester physics student (i.e. pre QFT, but far beyond the level of a news article for non-physicists, which avoids all details and only deals in ...
1
vote
3answers
167 views
Neutron decay and electron anti neutrino $n\to p + e + \bar{\nu}_e$
Why do we need neutrino to explain neutron decay?
Is there any evidence regarding existence neutrinos in the context of
$n\to p + e + \bar{\nu}_e$?
0
votes
1answer
152 views
How to calculate Rest Mass practically with Standard Model?
With relativistic physics, we can apply force to see resistance against acceleration. It'd give us relativistic mass and we have well established formula to get to the Rest Mass as long as we know the ...
3
votes
3answers
257 views
Does Standard Model confirm that mass assigned by Higgs Mechanism creates gravitational field?
I am not comparing passive gravitational mass with rest inertial mass. Is there an evidence in Standard Model which says that active gravitational mass is essentially mass assigned by Higgs mechanism.
...
3
votes
2answers
496 views
Does Dark Matter interact with Higgs Field?
Dark matter does have gravitational mass as we know from its discovery. Does it have inertial mass?
3
votes
1answer
88 views
Would the Standard Model allow two energetic photons to form a particle-like, zero-spin resonance?
The title is the question: Would the Standard Model allow two energetic photons to form a particle-like, zero-spin resonance?
6
votes
4answers
265 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 ...
0
votes
0answers
50 views
Which higgless models still predict a higgs-like resonance below the TeV scale? [closed]
Given today's announcement, I assume a bunch of wikipedia pages will need editing! The question is, which ones? Which higgless models still predict a resonance similar to the one observed by the ATLAS ...
1
vote
1answer
170 views
Why not accurate masses of elementary particles?
In the standard model of particle accuracy in calculating mass is very low.
And you can not predict the upper limit of Higgs particle mass accurately. Why not accurate masses of elementary particles?
0
votes
1answer
75 views
Future of colliders and technical limitations
Are there any technical limitations (theoretical or technological) that prevent quark based colliders? ie. Colliding two quarks together.
3
votes
1answer
177 views
Lepton Number Conservation
What is the global symmetry of the electroweak Lagrangian that gives rise to lepton number conservation?
As I understand it, electric charge is some linear combination of the conserved quantities ...
7
votes
3answers
658 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?
19
votes
5answers
1k views
Could gravity be an emergent property of nature?
Sorry if this question is naive. It is just a curiosity that I have.
Are there theoretical or experimental reasons why gravity should not be an emergent property of nature?
Assume a standard model ...
1
vote
1answer
358 views
Origin of the Higgs field
Are there any attempts in the literature at addressing the origin of the Higgs field? And, which lines of research that find it inevitable to address this question?
1
vote
1answer
129 views
Particle mixing and indistinguishability
Neutral kaons have two flavor combinations: $\mathrm{d}\bar{\mathrm{s}}$ and $\mathrm{s}\bar{\mathrm{d}}$. They can also be weak eigenstates: $\mathrm{\frac{d\bar{s} \pm s\bar{d}}{\sqrt{2}}}$.
But ...
3
votes
1answer
412 views
Introduction to Physical Content from Adjoint Representations
In particle Physics it's usual to write the physical content of a Theory in adjoint representations of the Gauge group. For example:
$24\rightarrow (8,1)_0\oplus (1,3)_0\oplus (1,1)_0\oplus ...
10
votes
0answers
276 views
A dictionary of string - standard physics correspondences
Motivated by the (for me very useful) remark
''Standard model generations in string theory are the Euler number of
the Calabi Yau, and it is actually reasonably doable to get 4,6,8, or 3
...
3
votes
2answers
363 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 ...
2
votes
3answers
403 views
Hilbert space and Lie algebra in quantum mechanics
We are looking for a publication or website that explains the Standard Model in terms of Hilbert space and Lie algebra.
We are reading Debnath's Introduction to Hilbert Spaces and Applications and ...
2
votes
0answers
58 views
How can one activate the decay of the quark b with PYTHIA event generator?
This is my problem and I hope finding a solution.
_In the simplest alternative, MSTJ(22) = 2, the comparison is based on the average lifetime, or rather (c*tau "time life") , measured in mm. Thus ...
7
votes
2answers
1k views
Why is the Higgs boson spin 0?
Why is the Higgs boson spin 0? Detailed equation-form answers would be great, but if possible, some explanation of the original logic behind this feature of the Higgs mechanism (e.g., "to provide ...
5
votes
1answer
220 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
1answer
118 views
Fine Tuned Universe
Is the fine tuning that cosmologists talk about (that our Universe is fine tuned for intelligent life) is the same as the fine tuning of the squared mass parameter of the Higgs in the Standard Model? ...
5
votes
2answers
333 views
More questions on string theory and the standard model
This is a followup question to
How does string theory reduce to the standard model?
Ron Maimon's answer there clarified to some extent what can be expected from string theory, but left details open ...
15
votes
2answers
1k views
How does string theory reduce to the standard model?
It is said that string theory is a unification of particle physics and gravitation.
Is there a reasonably simple explanation for how the standard model arises as a limit of string theory?
How does ...
6
votes
2answers
322 views
Neutrino oscillations versus CMK quark mixing
I wish to describe in simple but correct terms the analogy between the Cabibbo–Kobayashi–Maskawa (CMK) and Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrices.
The CMK matrix describes the rotation ...
3
votes
3answers
426 views
Building the meson octet and singlet
I am very lost in this topic. I understand that there are $3\times 3$ possible combinations of a quark and an anti-quark, but why should one decide arbitrarily (that's how it appears to me) that one ...
4
votes
3answers
568 views
Why are there 4 Dimensions and 4 Fundamental Forces?
Is it a coincidence that there are four fundamental forces and four spacetime dimensions ? Does a universe with three spacetime dimension contain four fundamental forces? Can magnetism be realized in ...
2
votes
1answer
185 views
In SUSY why does electroweak symmetry breaking only happen in the SM sector?
This is a difficult question to phrase succinctly, so I hope the title makes sense. What I want to understand is what seems like a lack of symmetry (besides SUSY-breaking) between the SM sector and ...
