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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13
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4answers
684 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
99 views

Width of the decay of Higgs boson into dimuon

According to Standard model, the partial width of the decay of Higgs into dimuon (up to tree level) is: $$\Gamma\approx\frac{m_H}{8\pi} \left(\frac{m_{\mu}}{\nu}\right)^2$$ with the Higgs mass ...
0
votes
1answer
57 views

What is the general definition of signal acceptance?

Suppose I have a beyond Standard Model theory and want to test it. I want to test if some experiments, say conduced in LHC, show signals of the theory. In this case, what is "signal acceptance"?
2
votes
0answers
21 views

Has the formation of a new quark pair as we separate two quarks been observed or is it only a prediction? [duplicate]

Because of quark confinement we know that as we try to separate quarks appart the energy required will increase, but if the force is strong enough (I do not know if possible in the lab, but at least ...
15
votes
3answers
8k views

Your Mass is NOT from Higgs Boson

Your Mass is NOT from Higgs Boson? http://www.youtube.com/watch?v=Ztc6QPNUqls This guy can't be correct, right? He argues that because mostly of a nucleus' mass is made out of the space between ...
0
votes
1answer
116 views

Why doesn't a changed particle ever lose energy by interacting with others by radiation of virtual photons? Are all virtual photons exchanged?

I've had it explained to me in a separate post that charged particles are constantly exchanging virtual particles with other charged particles and their energy is a steady state. How it is a surety ...
1
vote
1answer
89 views

How to explain electrons' interaction via the weak force?

What is the piece of theory which dictates that electrons interact via the weak force with other electrons and protons, and how can this force be understood in terms of what I am more familiar with ...
2
votes
0answers
39 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, ...
0
votes
1answer
88 views

Vector bosons: polar vectors or axial vectors?

The $W$ and $Z$ bosons are known as vector bosons, because they have non-zero spin. How do we know whether they are axial or polar vectors? Context: I am reading about a technique called Operator ...
5
votes
1answer
781 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 ...
0
votes
0answers
60 views

Is $\overline{B}^0$ really the antiparticle of $B^0$?

They have a different mass, which is apparently forbidden by $CPT$ symmetry. Does this have anything to do with them having two distinct energy eigenstates?
3
votes
1answer
173 views

Renormalizability of standard model

I'm wonder what precisely is meant by the renormalizability of the standard model. I can imagine two possibilities: The renormalizability of all of the interaction described by the Lagrangian before ...
2
votes
1answer
88 views

Gauge SU(2) with real triplet

I have come across a model of gauge $SU(2)$ with a real triplet. The covariant derivative for $SU(2)$ complex doublet is written as $$D_\mu=\partial_\mu-igT^aA^a_\mu$$ where $T^a$ are generators of ...
7
votes
1answer
390 views

What part does the Higgs boson play in conveying mass?

I am a high school physics teacher and did my physics degree a while ago, well before the Higgs boson was on in the physics undergraduate syllabus. Now, I am a little confused. The recent discovery ...
2
votes
2answers
157 views

What's the symbol for the antiparticle of the delta plus baryon?

It can't be $\Delta^-$ since that is another particle also made up of quarks (not antiquarks). I can think of four possibilities: $\overline\Delta^+$ $\overline{\Delta^+}$ $\overline\Delta^-$ ...
2
votes
2answers
46 views

At what energy do up and down quarks unbind?

At what energy do up and down quarks unbind? Google does not seem to have a clear answer. Could someone please represent this mathematically?
1
vote
1answer
81 views

Can we observe proton decay?

I know that the half life of a proton is more than $6.6\cdot 10^{33}$ years (antimuon decay). I have found this data on Wikipedia proton decay but I do not know the probability distribution that leads ...
1
vote
0answers
60 views

How to construct singlet and other multiplets from two triplets

Let an $SU(2)$ isotriplet operator is given by\begin{equation}\bar{l^c}i\tau_2\vec \tau l=l^T Ci\tau_2\vec \tau l\sim 3\end{equation} and an isotriplet Higgs field \begin{equation}\vec \Delta\sim ...
3
votes
2answers
311 views

Is there a connection between gluons and photons?

I was wondering if there is any sort of connection between a gluon and a photon since they are both considered massless.
10
votes
2answers
146 views

Why do fermions come in generations, but not bosons?

Why does the $1/2$ spin of fundamental fermions (electrons, quarks, and neutrinos) split them into three variants that differ only in mass, while the integer spins of massless fundamental bosons (e.g. ...
2
votes
1answer
195 views

Is this summary of modern theoretical physics correct?

This is not exactly a physics question; it's more of a question about physics. You'll see what I mean in a minute. My understanding of modern theoretical physics is below. What I want to know is: Is ...
4
votes
0answers
27 views

What are hadronic uncertainties?

I am reading articles about recent findings at CERN and the possibility of New Physics contributions, and they keep saying that the discrepancies may be due to hadronic uncertainties... What are ...
3
votes
1answer
130 views

Group theoretical reason that Gluons carry charge and anticharge

I was wondering how it is possible to see from the $SU(3)$ Gauge Theory alone that Gluons carry two charges colors: $g\overline{b}$ etc. Some background: The W-Bosons (pre-symmetry breaking) ...
3
votes
0answers
58 views

Why is Quark Mixing forbidden in the Lagrangian (pre CKM)

The corresponding term in Lagrangian for the coupling of quarks to gauge fields reads $$ \sum_{i} \bar Q_i D_\mu \gamma^ \mu Q_i .$$ Considering the Yukawa terms it is generally stated, that no ...
10
votes
3answers
1k views

Why does the weak force distinguish left and right handedness?

I'm wondering why the weak interaction only affects left-handed particles (and right-handed antiparticles). Before someone says "because thats just the way nature is" :-), let me explain what I find ...
5
votes
2answers
389 views

What prevents photons from getting mass from higher order Feynman diagrams

The Higgs boson and gluons have no electric charge and photons couple to charge, so there is no tree level interaction between them and photons. But what prevents higher order diagrams from ...
0
votes
1answer
36 views

Why is a “Semi-leptonic” Decay Mode called so?

Why is a semileptonic decay mode called so? I mean, if there is one lepton amongst the decay products, it should be leptonic, right? If there are two, that should be called bi-leptonic or something ...
0
votes
1answer
40 views

Unitarity of CKM matrix?

The CKM matrix is known to be unitary. Now, is it just found experimentally? Is the following idea correct? We know that the weak force eigenstate $ \left( \begin{array}{c} d' \\ s' \\ b' ...
1
vote
0answers
52 views

Origin of CP violation in CKM matrix?

I have already seen this question but I am not very familiar with the group theoretical framework of the Standard Model and was hoping for a more diluted answer. So I have come across this slide: ...
1
vote
1answer
62 views

Why does the $Z$ boson not change quark flavour?

Is it just an observation from Particle Accelerators data? I was trying to understand what is it that mathematically stops the $Z$ boson from changing quark flavour, if it is known?
5
votes
1answer
256 views

Chiral anomalies

Recently I have read that there is contraction of chiral anomalies in SM. But people are working on chiral anomalies theory. So I have the question: what is the importance of development of the theory ...
16
votes
2answers
992 views

Is the Standard Model consistent (UV complete)?

This is a question about the self-consistency of the Standard Model - which I believe is the same as asking whether it is UV complete - in other words, can it be used to predict experimental results ...
2
votes
1answer
33 views

What theory unifies the electroweak and the strong forces? [closed]

As the title itself suggests, here's my question: What theory unifies the electroweak and the strong forces?
9
votes
1answer
268 views

Anomalously broken conformal symmetry

I'm trying to understand an argument made by Bardeen in On Naturalness in the Standard Model. The argument is about quadratic divergences in Standard Model. My notation is that the SM Higgs potential ...
1
vote
1answer
68 views

What does the first column in the “decay modes” table mean (in Particle Data Group documents)?

As a follow-up to this more general question, what are the values in the first column of each of the "decay tables" in a PDG document describing? What are those things in the first column? Are they ...
8
votes
2answers
683 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 ...
1
vote
0answers
64 views

$G$-parity in an electromagnetic decay

I am looking at the decay $\eta\rightarrow\pi^+\pi^-\gamma$ and I would assume that the decay itself (ignoring the $\pi\pi$ final state interaction that is obviously strong) is electromagnetic since ...
4
votes
3answers
263 views

Majorana Mass For Neutrinos In Standard Model

Neutrinos can't be given Dirac masses because there is no $SU(2)_L$ singlet right handed neutrinos in the standard model. But can neutrinos be given Majorana masses in the standard model? EDIT: Why ...
3
votes
0answers
84 views

Understanding the effective low-energy Lagrangian for hadrons

My course in Higgs Physics is discussing a two-nucleon low-energy effective theory of hadron interaction. With $\psi=(p,n)$, the pion is defined as $\vec{\pi}= i \bar{\psi}\vec{\tau} \gamma_5 ...
1
vote
2answers
107 views

What is the reason for the $ i \tau_2 $ - factor in the higgs coupling with up-type quarks?

The quark mass term in the Standard Model Lagrangian looks like this: $$ L = - \lambda_d \bar{Q}\phi d_R - \lambda_u \bar{Q} i \tau_2 \phi^* u_R $$ What is the reason for the $ i \tau_2 $ - ...
1
vote
2answers
117 views

Subatomic particle mass and Benford's Law

Nine out of 15 subatomic particle masses begin with the digit one. Benford's Law would imply 30% with one as the leading digit. Is there any significance to this frequency distribution, such as ...
3
votes
1answer
352 views

Is the Higgs Boson a Force Carrier? [duplicate]

I am told there are four fundamental forces, and each of these forces has a boson that acts as its carrier. Reading this http://www.fnal.gov/pub/science/inquiring/questions/higgs_boson.html I find ...
7
votes
1answer
397 views

Why mass terms are forbidden?

I would like to clarify my understanding on why mass terms in Lagrangians of gauge theories are forbidden. It's often repeated that particle masses are forbidden by electroweak symmetry because it is ...
3
votes
2answers
75 views

Uniqueness of W,Z bosons

What is real reason for considering only ONE unique W and Z bosons, and not of 3 separate flavors, in the Standard Model?
3
votes
2answers
547 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 ...
4
votes
1answer
136 views

Higgs Mechanism

In Higgs mechanism, we take the combination of LH $SU(2)$ doublet and RH singlet along with Higgs doublet so that the overall weak hypercharge and weak isospin is zero to be $SU(2) \times U(1)$ ...
1
vote
1answer
125 views

Do massive particles exchange Higgs bosons?

Do massive particles exchange virtual Higgs bosons between themselves? If they do does the resulting Higgs force decay exponentially with distance?
11
votes
1answer
489 views

Justification for new theories of Particle Physics and General Relativity

In reference to arxiv:1212.4893v3 and arxiv:1206.5078v2 papers of Ma and Wang, they have proposed new theories in particle physics, the weakton model where quarks and leptons are formed using these ...
4
votes
0answers
171 views

Effective Field Theory (EFT) decoupling top

The decoupling theorem of Appelquist-Carazzone says that if you want to decouple a particle, the low energy resulting theory need to be renormalizable. You can't do that for the top, because you break ...
62
votes
5answers
7k views

How literally should you take “The Higgs boson gives other particles mass”?

A standard phrase in popular discussions of the Higgs boson is that "it gives particles mass". To what extent is this a reasonable, pop-science, level of description of the Higgs boson and it's ...