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 ...

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2
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4answers
6k views

Why is Neutron Heavier than Proton? [closed]

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 ...
6
votes
3answers
900 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 ...
0
votes
0answers
109 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
422 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 ...
13
votes
0answers
333 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
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1answer
304 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 ...
1
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0answers
67 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
1answer
315 views

Is Connes model a composite Higgs in disguise?

Most of the 5-dimensional Higgs models can be seen, if I understand correctly, as models where the Higgs is a composite. Now, is this true for Connes models? It is a model of extra dimensions too, ...
2
votes
2answers
185 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
2k 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 ...
8
votes
0answers
802 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 ...
5
votes
3answers
992 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 ...
6
votes
0answers
181 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 ...
11
votes
2answers
684 views

How does Annihilation work?

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 ...
1
vote
1answer
436 views

Why has the Higgs potential the form it has?

The potential for the Higgs field is 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 potential ...
2
votes
3answers
387 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 $n\to p + e + \bar{\nu}_e$?
5
votes
2answers
206 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 ...
-6
votes
2answers
339 views

Why did Standard Model never sense a requirement to include gravitational quantum? [closed]

Standard Model is advanced (lorentz invariant) version of Quantum physics. It tried to include everything which came in the way while understanding quantum world. It even didn't bother to include ...
4
votes
3answers
365 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. ...
16
votes
2answers
2k views

What happens to matter in a standard model with zero Higgs VEV?

Suppose you reset the parameters of the standard model so that the Higgs field average value is zero in the vacuum, what would happen to standard matter? If the fundamental fermions go from a finite ...
0
votes
1answer
446 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 ...
4
votes
2answers
1k 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
101 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?
5
votes
2answers
569 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 ...
1
vote
1answer
271 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?
3
votes
1answer
495 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 ...
0
votes
1answer
100 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.
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2answers
420 views

why is dark matter the best theory available to explain missing mass problems?

Why is dark matter the best theory to explain the missing mass problem? Why is dark matter mathematically necessary to explain the missing mass problem? On a side not I believe dark matter is ...
5
votes
1answer
373 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 ...
1
vote
1answer
819 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?
2
votes
1answer
191 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 ...
5
votes
1answer
942 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 ...
1
vote
0answers
223 views

What are the prerequisites to study CP violation?

If one would like to study CP violation, what would be the prerequisites for it? For example, until now I have not studied quantum field theory and have done very little classical field theory, but ...
5
votes
1answer
314 views

How do physicists know that mass of possible Higgs particle is limited between two values?

How do physicists know that mass of possible Higgs particle is limited between two values 90 GeV/c$^2$ and 145 GeV/c$^2$?
5
votes
3answers
3k 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 ...
0
votes
1answer
177 views

“Conceptualizing” neutrinos

Layman here. EE and BS physics. I am "content" in viewing photons/electromagnetic radiation as an "emergent" property of spacetime? due to the electrons ("particles..?") and all their activity jumping ...
23
votes
0answers
1k 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
0answers
224 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 ...
12
votes
4answers
8k views

Why don’t photons interact with the Higgs field?

Why don’t photons interact with the Higgs field and hence remain massless?
9
votes
2answers
4k 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 ...
6
votes
1answer
770 views

Is there an explanation for the 3:2:1 ratio between the electron, up and down quark electric charges?

I understand that the NNG formula relates $Q$, $I_3$, and $Y$ and can be derived in QCD; does this unambiguously predict the electric charge ratios without making assumptions about the definitions of ...
4
votes
1answer
194 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? ...
8
votes
2answers
557 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 ...
21
votes
2answers
3k 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 ...
1
vote
1answer
337 views

What really is the future about the Standard Model

The fact that the bosons of the weak force have mass is something that I think technically poses many problems. To avoid this and other problems with the masses of the particles devised a mechanism ...
3
votes
3answers
1k 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 ...
11
votes
2answers
1k 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 ...
5
votes
3answers
1k 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 ...
30
votes
4answers
12k 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 ...
4
votes
3answers
416 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 ...