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Questions tagged [standard-model]

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 and weak nuclear forces (and the Higgs mechanism). Do NOT use this tag for the standard model of cosmology, etc..

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 and weak nuclear forces (and the Higgs mechanism). Do NOT use this tag for the standard model of cosmology, etc..

The Theories of the Standard Model

The theories combined by the Standard Model of particle physics are:

The Standard Model, describes all experimentally known fundamental interactions, except for gravity, which is classically described by .

A candidate for a consistent framework that accommodates the physics of the Standard Model with gravitation is . Other shortcomings of the Standard Model include the vastly large number of dimensionless constants, the need for renormalisation, etc.

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Do standard model particles actually exist or merely usefully describe behaviors of a medium?

I've read about how sound propagation can be modeled as phonon particles moving and interacting. I understand that this is a useful mathematical construct to describe the behavior of longitudinal pressure waves in a medium like air. Are standard…
William Grobman
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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, it seems too much for a quantity that is supposed…
arivero
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What is the origin of flavor?

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 electrons, there are strange, charm, muon, tau, etc.. I am…
jdm
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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 creates a down quark. Strong field creates a…
Gert Cuykens
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Area spanned by unitarity triangle of CKM matrix

I currently read an article and they mentioned, that using the unitarity relation between the 1. and 3. column of the CKM matrix, one can easily show that the area spanned of the unitarity triangle is given by $2A =…
nerdizzle
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In Standard Model, are $W_{\mu}^3$ and $B_{\mu}$ *interaction* eigenstates?

In Standard Model, after electroweak symmetry breaking, the $W_{\mu}^3$ and $B_{\mu}$ fiels mix in order to form the $Z$ and $A$. Before electroweak symmetry breaking, are $W_{\mu}^3$ and $B_{\mu}$ interaction eigenstates ? After electroweak…
Mathieu Krisztian
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What is the importance of higher generations of particles in cosmology?

Although there are 6 types of quarks and 3 leptons according to the standard model, most of them are unstable and rapidly decay to the lighter, first generation analogues. Only the up and down quarks and the electron make up a substantial fraction…
someone_else
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Is there a theoretical upper limit for the Yukawa-like coupling constant in a theory with a cut-off scale?

In the fermion mass terms in the Standard Model, $y_x\bar{L}H d_x$ or $y_x\bar{L}\tilde{H} u_x$ where $y_x$ are the Yukawa couplings, we have $y_x<<1$ except for the case of the top quark. For the top quark, $y_t \sim 1$. As I understand, this is…
user713320
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How accurate is the Standard Model at explaining everyday phenomena? How do we know the answer?

I've read many times that "the Standard Model can explain all everyday phenomena (except gravity)." But I haven't been able to find out what exactly is meant by this. If I were to simulate (theoretically) some everyday object.. say myself over a…
user
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Particle coupling predictions of the Standard Model

It's widely noted that the Standard Model does not predict the existence of flavor or the three lepton families: We put those facts into the Lagrangian "by hand" for agreement with observations, not due to any a priori requirement of Quantum Field…
Jim Eshelman
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What if we heated the universe to a temperature above the Higgs phase transition?

If it were possible to get the Universe, or a subset of it, back to the energy scale where spontaenous symmetry breaking and the electro-weak transition happened, what would happen? Would we see phenomena mediated by $W^1, W^2, W^3$ and $B$? If we…
SuperCiocia
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Why does the running of the gauge couplings show $\frac{1}{\alpha}$ > $\frac{1}{\alpha_w}$ at low energy?

I thought the coupling constants were something like: $\alpha \approx 1/137$ $\alpha_w \approx 10^{-6}$ $\alpha_s \approx 1$ And yet if you look at any pictorial representation of the running of the couplings you see something like this (or try…
user1247
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Matching interaction terms and decay processes in Standard Model

I would like to consider the interaction terms in the Standard Model which allow the following decay process: The only interaction terms in the Standard Model which allow this decay process are contained in the charged current…
nightmarish
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Real and virtual photons in the standard model

In the Standard Model, the mass of the photon is zero, while the photon becomes massive if it acts as a mediator between two electrons. Why does this happen? Does it mean that the Standard Model cannot describe the interaction between two electrons?
Archi
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Why don't the phases common to rows or columns in the Cabibbo-Kobayashi-Maskawa matrix matter?

As the tittle says, I want to know why don't the phases common to rows or columns in the Cabibbo-Kobayashi-Maskawa matrix matter?
Yossarian
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