Questions tagged [higgs]

This higgs field breaks electroweak symmetry and provides mass to particles though a process called the higgs mechanism. The excitation of the higgs field is called a higgs boson.

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How do I calculate the amplitude of an $s$-channel Feynman diagram?

What is is the starting point to measure the amplitude in an $s$-diagram like the one below where two particles collide and create a propagator followed by the final product? I know that in $t$-...
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How am I meant to use momenta and polarisation vectors in a Feynman diagram?

I'm trying to calculate the tree-level amplitude of a diagram and I am given the momenta and the polarisation vectors. How do I use these to get to the simplest form of the amplitude. What is the ...
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What is the meaning of the structure constant for the $\rm SU(3)$ group and how I can find its values? [duplicate]

To calculate the tree-level amplitude for: $$Z(p_1) + Z(p_2) \to Z(p_3) +Z(p_4)$$ I must take into the consideration, amongst other cases, the amplitude for: I know the values shown in another post ...
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How do I find the values for the structure constants ($f^{abc}$) of a gauge group?

How do I find the values for the structure constants ($f^{abc}$) of a gauge group, as a mean to find the tree-level amplitude for a process in which one of the tree-level diagrams is: the process ...
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The Higgs mechanism in a quiver gauge model

I've been reading chapter 20 in Peskin and Schroeder about the Glashow-Weinberg-Salam Theory for a $U(1)$ gauge symmetry with gauge coupling strengths $g$, and a complex scalar $\phi$, specifically ...
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Why do people say that neutrinos are either Dirac or Majorana fermions?

The question of whether a given particle "is" a Dirac or Majorana fermion is more subtle than is sometimes presented. For example, if we just consider the "old" Standard Model with massless neutrinos, ...
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Higgs vev: diagonal or not?

I've read at different, places (for instance, this answer) that you can choose the vev of an adjoint Higgs to correspond to a generator of the Cartan subalgebra of the symmetry you are trying to break....
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Symmetry breaking and higgs representation

I was wondering if there is a criterion for the representation the Higgs should change under or if it's a case by case scenario. For instance, electroweak symmetry breaking is done with a higgs in ...
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Photons, Gravity and Higgs field [closed]

(a) A photon's path bends towards a large mass, so we say it has gravitational attraction (or that the large mass bends spacetime so that the photon's path curves towards it). But if the photon feels ...
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Energies needed for massive particles to reach light speed, such as W/Z bosons at electroweak energy levels - limitation of special relativity?

I have learned that before 10^-32 s after the big bang, when the universe was at 10^15 degrees Kelvin, particles that carry the weak nuclear force, the W and Z bosons (which have mass), no longer ...
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What is the energy of the vaccuum : is it the average of $<\phi_H>$, or the value of the potential?

If we consider Higgs boson theory, the Higgs potential which is introduced is a mexican hat potential. Before electroweak symmetry breaking, the field is exactly 0, and the potential is non null. ...
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Gauge fixing, Lorentz invariance and positive definite metric of Hilbert space

Updated 0n ${\bf 02.04.2020}$ $\large{\bf Context}$ In the first $3$ minutes of this video lecture (based on the presentation here) on the subject matter of Goldstone theorem without Lorentz ...
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What is electric charge made of? [duplicate]

Hear me out. When asked what is mass made of, I can roughly say it is the interaction between the particle and higgs field or energy of quarks, boson, what have you. Now I ask what is charge made of? ...
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Why does probing Higgs self coupling provides information on *dynamics* of Electroweak Symmetry Breaking?

Why does probing Higgs self coupling provides information on dynamics of Electroweak Symmetry Breaking ? Also, Why does probing Higgs self coupling provides information whether Higgs boson is ...
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Higgs mechanism and spontaneous symmetry breaking

I'm really confused about spontaneous symmetry breaking and the Higgs mechanism. I've searched for other answers but I couldn't still resolve all my doubts. I also understand that I'm asking a lot of ...
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Why is SM Higgs a doublet?

Based on my C grade of QFT (technically F in grad), I learned that a complex scalar field can give mass to a maseless gauge boson by SSB, with real component becoming a massive higgs, and orthogonal (...
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Higgs self-energy at finite temperature

Is there anybody know of a reference that calculates the Higgs self-energy at finite temperature, say in a Standard Model plasma?
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How do the massive gauge bosons eat up the would-be Goldstone bosons?

In the literature one often reads that the would-be Goldstone bosons of the spontaneously broken $SU(2)\times U(1)$ symmetry are eaten up by the longitudinal polarisation vectors of the now massive ...
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Can the Higgs particle escape a black hole? [duplicate]

The higgs particle or field is what gives mass to everything. It's said that nothing can escape a black hole. If that is true how can the black hole "tell" its mass as even the higgs would not be able ...
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Why hasn't Peter Higgs solved the Yang-Mills prize problem?

The Higgs mechanism gets rid of the mass gap problem, and it's been experimentally proven, so why is there still a problem? Why are the million dollars still up for grabs?
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Amplitudes with external gauge bosons in Feynman gauge

If I want to compute the tree amplitude for 2 particles annihilating into 2 gauge bosons, for example, $h h\to Z Z$ in the Standard Model (SM), and I use Feynman gauge, is it necessary to include ...
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Why hasn't the false vacuum collapsed yet?

The Standard Model, and current measurements of the Higgs mass, suggest that our universe is in a metastable state, which may catastrophically collapse into a false vacuum. https://en.wikipedia.org/...
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What mechanism gives mass to elementary particles in string theory?

Nowadays it's assumed (it can still turn out to be different) that elementary particles are "given" mass by interaction with the Higgs field. I read in the only answer to this question: If you ...
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Higgs mechanism in superconducting phases

Are some of you guys able to instruct a curious solid-state physicist new to superconductivity about how the Higgs mechanism is related to the Meissner effect or more generally to gauge symmetry ...
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What is the density of Higgs Boson at different places

I understand that the Higgs Field is everywhere, but I don't have a feel for the density, or number, of Higgs Bosons in an area - say 1 cubic metre. Is there 1 mole of HB for every mole of quark in a ...
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Could there be something like the Higgs field which gives particles their energy in a similar way the Higgs boson gives particles their mass?

First of all, in no way do I have advanced knowledge of particle physics, quantum mechanics, or any other necessary scientific concept for a full understanding of this question. Secondly, this is ...
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Vacuum expectation value (VEV) of a Gauge theory - Spontaneous Symmetry Breaking (SSB) - Higgs Mechanism

I am dealing with a sort of scalar QED with a term of SSB \begin{equation} \mathcal{L}=\left|D_{\mu} \phi\right|^{2}-\frac{1}{4}\left(F_{\mu \nu}\right)^{2}-V\left(\phi^{*} \phi\right) \end{equation} ...
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Why is 2nd-order time derivative crucial to Higgs/amplitude mode?

I read in this paper (page 11 first a few sentences) that 2nd-order time derivative in the action or the equation of dynamics is indispensable for the excitation of Higgs/amplitude mode. The paper ...
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Peskin Schroeder Higgs mechanism for an $SU(3)$ gauge theory with a scalar field $\varphi$ in the adjoint representation

In Peskin Schroeder pag.696 a Higgs mechanism for an $SU(3)$ gauge theory with a scalar field $\phi$ in the adjoint representation is presented. The covariant derivative of $\phi$: $$ D_{\mu}\phi_{a} =...
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Does the shape of the Higgs mexican hat depend on the temperature of the universe?

I am reading this paper and i wonder if it is mainstream. Does the VeV of the Higgs field evolve with time? What about the mass given to the fermions?
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Why are the masses of $W^{\pm}$ and $Z^0$ different?

We know that through the Higgs phenomenon, the weak bosons become massive. In our Lagrangian the $W^\pm$ boson is usually defined as $\frac{1}{\sqrt{2}}(W^1_\mu\mp iW^2_\mu)$ and $Z^o$ is usually ...
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When the EM vector field is given a mass by Higgs mechanism, why isn't this equivalent to a massive photon?

In chapter 6 of Classical Theory of Gauge Fields (Rubakov), we are presented with a scalar field $\phi$ coupled to the electromagnetic vector potential $A_\mu$. In this Lagrangian there is a quartic ...
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Two Higgs doublet model

Are there any papers which explain introduction of two Higgs doublet model? I would like to know the introduction. I am not working on the theory side but on the experiment side.
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Non-Abelian Higgs mechanism of Schwinger in 'Wikipedia

https://en.wikipedia.org/wiki/Higgs_mechanism#Examples in "Non-Abelian Higgs mechanism" quotes an "early electroweak model due to Julian Schwinger. In this model, the gauge group is SO(3).... and the ...
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How is mass-energy conserved during false vacuum decay?

If we live in the false vacuum, there is a probability that spontaneous vacuum decay could occur: quantum fluctuations could result in a bubble of true vacuum that expands at the speed of light. In ...
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Why do photons and gluons not interact with the Higgs field? [duplicate]

I'm looking for a non-mathematic answer as I am yet to begin studying physics or calculus, still half a year away. Just a simple explanation in layman's terms. As i understood it, electrons for ...
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Why can the masses of the Higgs and top quark determine whether we live in a false vacuum?

I read in the paper linked below that the ground state of the universe depends on the potential of the Higgs field, particularly the graph of the Higgs potential with its minima and maxima. I think I ...
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if Higgs boson stopped existing, what would happen? [duplicate]

If The Higgs boson and field ceased to exist (starting now), then would particles zip around at the speed of light, or would they gain mass from $E=mc^2$? Or would something else happen?
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Glashow-Weinberg-Salam (GWS) Theory for Gauge Boson Masses

I am supposed to find the mass of the $W^\pm$ and $Z$ bosons from the following covariant derivative: $$D_\mu = \partial\mu - \frac{ig_1}{2}B^\mu -ig_2t^iW^{i\mu} $$ and from $\mathcal{L}_{kin. ...
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Higgs mechanism and phase transition

Generally speaking, phase transitions divide into two types: First order and second order. To me, Higgs field's SSB sounds like a second-order one though I don't know the dependency of Higgs field's ...
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Do expectation values of quantum fields behave like classical fields?

A famous result in quantum mechanics is Ehrenfest's theorem which states that the expectation values of observables are governed by the classical equations of motion. Does a similar statement hold ...
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Higgs mechanism and gauge symmetry

In the case of massive bosons of weak interaction we have Higgs mechanism to save the symmetry. I do not see how with Higgs the symmetry is preserved? Because the mass term is what gives us problems ...
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Higgs Yukawa coupling explicitly violating chiral symmetry

I'm pretty confident that I'm misunderstanding something here. The Yukawa coupling that couples the Higgs field to fermions can be written something like: $$ \lambda \bar L H e_r + h.c., $$ where $L,...
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Why Higgs field need hypercharge to work?

I know that photon and gluon don't have any hypercharge so they can zip through higgs field at speed of light while left and right handed particles seems to communicate with these hypercharge, so then ...
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Can we tell the difference between a scalar field and a non-linear sigma model?

Suppose a $U(1)$ non-linear sigma model field $\Sigma(x)$ take values on a circle. But if this circle is very large and the value don't vary so much, shouldn't this be almost identical to a scalar ...
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Why is the Higgs boson chargeless?

Well, I know if this question was asked about another particle the answer would be that the charge of a particle in an intrinsic property and that’s that(as far as we currently know), and that might ...
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Higgs interaction

I have a question about mass and energy and the Higgs field. My understanding is that fermions 'gain' rest mass by interacting with the Higgs field. But mass is a form of energy, so is the rest mass ...
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Vacuum decay in QFT (flat spacetime): Help me

I start explaining my doubt from the properties of the vacuum: the vacuum is a quantum state $|0>$ of minimum energy for which the vacuum expectation value of our (scalar) field $<\phi>_{VEV}=...
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Resources to understand the Higgs boson

I have to do a presentation about the Higgs boson, covering topics such as the problems with the standard model without Higgs, particle masses not being compatible with gauge symmetry and how it is ...
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Temperature dependence of the Higgs VEV

Presumably, The Higgs field vacuum expectation value has a strong temperature dependence close to the electroweak symmetry breaking phase transition. Does this have known consequences for the ...

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