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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1answer
973 views

What is the relationship between the Higgs field and quarks?

I have some difficulty considering the relative size of each and the meaning behind the shape of Higgs boson. I ask relating to the structures of both the Higgs field and quarks. How is it that the ...
0
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0answers
22 views

Subnuclear reactions: combining quarks

When you try and pull two quarks apart, you don't get two separate quarks, but instead: the energy stored in the field between them gets high enough to create more quarks, and instead of two ...
4
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2answers
216 views

Are antimatter particles made of ---?

Consider some particle P, and the antiparticle aP. Is it the case that: aP is made of the "usual" elementary particles, and indeed the same elementary particles as P, but arranged (or something) in ...
3
votes
2answers
149 views

Feynman diagram for attractive forces

I’m looking at Feynman diagrams for attractive forces and I'm thoroughly confused. Below are three diagrams from HyperPhysics: These all illustrate instances where the forces are attractive. ...
2
votes
1answer
51 views

Why aren't all possible VEVs of the Higgs field in (quantum) superposition?

It is is usually said the the Higgs field chooses a Vacuum Expectation Value (VEV), around which we now expand our field operators. From this a mass term emerges, and one or more gauge fields acquire ...
0
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1answer
55 views

What is the gauge field in Bose-Einstein condensation?

The Hamiltonian for bosons has $\phi^{\dagger}\phi$ terms in it which makes it U(1) invariant. Bose-Einstein Condensation apparently breaks such symmetry by choosing a definite phase, even though I ...
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4answers
74 views

Change in the half-life of a neutron

What would happen if the half-life of a neutron was much more less than it is now? How could this affect the nuclei?
4
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1answer
228 views

What does the discovery of a pentaquark signify?

at a particle collider a pentaquark was discovered. My question in short is what does the discovery of a pentaquark signify? Is there a theory that it supports or something like that?
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2answers
37 views

Pair annihilation - can annihilation be moderated?

I recently asked this question: How close does a particle-antiparticle pair need to be for annihilation to happen? And that received a good answer. But there was a second part to my question that ...
10
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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 ...
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0answers
22 views

QCD condensate and lepton mass

I read that the QCD U(1) anomaly is caused by the QCD condensate giving rise to quark masses. Does the QCD condensate also give masses to leptons (electron, mu, tau, neutrinos), or are these masses ...
0
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0answers
33 views

Anomalies, neutrino condensate and neutrino masses

Is neutrino number conservation not affected by the U(1) QCD and QED anomalies due its zero U(1) charge? Is this the reason why the neutrino should be massless and there should be no lepton family ...
1
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0answers
41 views

Chiral anomaly and fermion number conservation

Chiral anomalies in QED and QCD violate fermion number conservation, since a U(1) vector symmetry corresponds to fermion number conservation. However, only the LH and RH fermion numbers are not ...
2
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1answer
103 views

Feynman diagrams and gluon collisions/interactions?

We have been given this question which essentially asks us to draw the lowest order Feynman diagrams for various processes. One of them is: $$ g + g \rightarrow \bar{t}+t $$ Now, I am not an expert ...
-2
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1answer
61 views

Fundamentals for predicting the standard model? [closed]

. Now, the question(s). What must a theory include to be consistent with the standard model? What concepts/ fields must be predicted?(such as predicting a Higgs field, gauge groups, particles being ...
5
votes
1answer
269 views

Is the long range neutron-antineutron interaction repulsive or attractive?

I can model this interaction as Zee does in "Quantum field theory in a nutshell". In chapter I.4 section "from particle to force" he uses two delta functions for the source. The integral gives ...
3
votes
1answer
92 views

Spontaneous symmetry breaking of anomalous global abelian symmetries and $U(1)$ of QCD

Let me restate the $U(1)$ problem of QCD: Let us forget about the $s$ quark, and consider the $u$ and $d$ massless. This is a good approximation since $m_{u,d} \ll \Lambda_{QCD}$. Then ...
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0answers
33 views

Massless Dirac Field Chirality and CP

I have some very basic questions about Quantum Field Theory. So let's assume we have massless fermions. In 4 spacetime dimensions, due to the Group Structure of $SO(3,1)$ there exists the famous ...
2
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0answers
82 views

Is there any additional complexity in the physical laws that seems unnecessary for us to exist? [closed]

I am wondering if the universe is as simple as possible, at least given the constraint that humans exist on Earth. This is my second attempt at this question, which was marked as too broad, since I ...
3
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3answers
163 views

Are field theories special?

Our best descriptions of the microscopic world, that satisfy many fundamental requirements (as we know them today), are field theories. Is there something fundamental about field interactions, or are ...
2
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2answers
130 views

Simulation of everyday life based on standard model [closed]

If I were to model the standard model, say on a super powered computer (which does not necessarily have to exist in the real world), would I get molecules, chemistry, life? I want to understand the ...
3
votes
1answer
128 views

Quark mixing vs neutrino mixing, mass eigenstates, weak states and detection

I have some doubts regarding the CKM matrix in the quark sector and PMNS matrix in the leptonic sector. Let us call $(d^\prime, s^\prime, b^\prime)$ the weak basis for quarks and $(d,s,b)$ the mass ...
1
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1answer
65 views

Three gauge bosons vertex

I was told that two $Z$ bosons could not decay to one (virtual) $Z$ boson at any loop level. Is it true? if so, why? Does it also hold for photons? Could we generalise the statement to "There cannot ...
3
votes
1answer
287 views

What is the meaning behind the neutrino oscillation parameter?

As far as I can tell, there are 6 parameters that describe how a neutrino oscillates: 2 mass squared differences, 3 mixing angles and another parameter I don't understand at all (delta). Thus I have ...
0
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1answer
150 views

What's the significance of neutrino oscillations? [duplicate]

I read some about neutrino oscillations and flavour changing between three types of neutrinos. The question is, what is the significance of that observation? So far, we did not expect them to ...
8
votes
2answers
326 views

Do solar neutrinos actually oscillate between electron, mu and tau?

I was reading up on the history of the solar neutrino problem, and as far as I can understand it, neutrinos supposedly oscillate from one form to another, thus explaining why there were only one-third ...
8
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4answers
1k 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 ...
1
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1answer
161 views

Why are the neutrino flavour eigenstates and mass eigenstates different?

Why does this happen for neutrinos and not for say, electrons and muons. Is there some way to predict which particles might oscillate amongst their flavour and which won't?
28
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2answers
787 views

Identification of particles and anti-particles

The identification of an electron as a particle and the positron as an antiparticle is a matter of convention. We see lots of electrons around us so they become the normal particle and the rare and ...
11
votes
3answers
2k views

Are electrons just incompletely evaporated black holes?

Imagine a black hole that is fast-approaching its final exponential throws of Hawking evaporation. Presumably, at all points in this end process there there will remain a region that identifiably ...
1
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2answers
323 views

Can all fundamental forces be repulsive?

If the electric force can be attractive (with opposite charges) or repulsive (same charges), and the magnetic force acts like this too, can all forces be repulsive in some cases? For example, could ...
10
votes
2answers
250 views

Can the up quark still be massless?

It used to be commonly discussed that the bare mass of the up quark can be $0$. This was because we can't observe its effect directly. To my knowledge the up quark can only be measured by its effect ...
3
votes
1answer
97 views

Are there Planck units for weak or strong “charge”, similar to the electromagnetic Planck charge $\sqrt{4~\pi~\epsilon_0~\hbar~c}~$?

Are there Planck units for "charge" of weak or strong interaction, similar to the Planck unit of electromagnetic charge: $\sqrt{4~\pi~\epsilon_0~\hbar~c}$ ? Are there perhaps direct substitutes, ...
2
votes
1answer
61 views

Evidence for standard model description of neutrons

as I don't know too much about experiments I have the following question concerning the evidence about the quark constituents in neutrons. After a quick google investigation I found some sentences ...
31
votes
7answers
2k views

How can the unstable particles of the standard model be considered particles in their own right if they immediately decay into stable particles?

How can the unstable particles of the standard model be considered particles in their own right if they immediately decay into stable particles? It would appear to a layman such as myself that these ...
14
votes
4answers
488 views

Weak contribution to nuclear binding

Does the weak nuclear force play a role (positive or negative) in nuclear binding? Normally you only see discussions about weak decay and flavour changing physics, but is there a contribution to ...
1
vote
2answers
99 views

How do protons and neutrons interchange?

I recently read in a book that a nucleon with +1/2 isospin is a proton and if the isospin is changed to -1/2, it is a neutron, so it is the same particle in different states. If a proton has a ...
25
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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 ...
0
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1answer
221 views

Why is neutral sigma baryon more massive than lambda baryon?

Neutral sigma-star baryon, neutral sigma baryon and lambda baryon have masses 1387 MeV, 1192 MeV, 1116 MeV respectively, whereas each of these 3 particles are composed of 1 up, 1 down and 1 strange ...
0
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0answers
56 views

What are the dominant decay products of upsilon meson?

Upsilon meson may decay to phi or omega meson but these should be OZI suppressed as in this case, bottom and antibottom quarks of upsilon meson will have to first annihilate to high energy gluon. ...
2
votes
3answers
163 views

Discovery of spin-3 particle at LHCb

I just read a discussion on the CERN website regarding first observation of a heavy flavored spin-3 particle at LHCb. This appears to be a post from last July. Is there anyone knowledgeable enough in ...
5
votes
2answers
761 views

Each elementary particle has its own field. What about antiparticles?

I understand how particles correspond to their respective fields. What about antiparticles though? Do they have separate fields as well?
-2
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1answer
50 views

Are there different colors of leptons? [closed]

Are there different colors of leptons? The Pauli Exclusion principal made it necessary for quarks to have 3 different colors. However, although leptons don't undergo the strong interaction they still ...
5
votes
3answers
1k 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 ...
0
votes
2answers
96 views

Color Force & Nuclear Force [closed]

I was wondering if the color force and nuclear force are both sub-forces of the Strong Interaction? If so is the Strong Interaction responsible for any other forces?
0
votes
0answers
62 views

Quantum Flavordynamics and messenger particles

My question is about messenger particles and how they relate to the concept of flavordynamics. I know that messenger particles travel between other particles to "communicate the force" like a photon ...
0
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0answers
44 views

Does core of a proton exist? [duplicate]

I understand a proton is made up of quarks/gluons. I want to know if a proton has an actual core? Also whether protons have a core/surface temperature.
1
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2answers
112 views

Why do we assume that particles and their antiparticles have the same half-life?

Has it been proven experimentally? What would the consequences be if their half-lives were different?
9
votes
1answer
1k views

What is a quark condensate?

What is a quark condensate? is it a bound state between 2 quarks? can we have 3(or more)-quarks condensate? What mediates the interaction between the constituents of the condensate? Are the ...
15
votes
3answers
729 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, ...