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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Regularization methods' equivalence and the hierarchy problem

There are several questions related to this one but whose answers just raise the doubt I'm going to describe here. Some facts that are everywhere are (i) The hierarchy problem results from the fact ...
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Physical degree of freedom and gauge fixing?

I'm confused with the gauge fixing in the Higgs mechanism. So if we have an action like $$S=\int |D\phi|-\frac{1}{4}F^2 -V(\phi) ~ ,\tag{1}$$ then expand around some non-trivial vacuum, then we have ...
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Mass parameters in the spontaneous symmetry breaking

In Ashok: Lectures on Quantum Field Theory Sec. 7.5 p.279 he discusses the mass parameters for the potential $$ V = -\frac{m^2}{2}(\sigma^2+\xi^2) + \frac{\lambda}{16}(\sigma^2 + \xi^2)^2. $$ My (...
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Why does the Higgs boson have electroweak charges $~T_3~$ and $~Y_w~$ but does not have an antiparticle with opposite charges?

(Using $Q=T_3+Y_W$) The Higgs boson has weak isospin $T_3=-\cfrac12$ and weak hypercharge $Y_W=+\cfrac12$. Since every particle has all opposite charges of its antiparticle, why isn't there an anti-...
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Cosmic strings and ground state degeneracy in SSB

There are two conflicting perceptions that I have regarding the notion of ground state post-SSB. Consider the Higgs mechanism e.g. for the electroweak theory. On the one hand, we say that the vacuum ...
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Higgs critical temperature?

Higgs mechanism is defined to operate (give spontaneous symmetry breaking) below some critical temperature. As mentioned, for ex. in Wikipedia: Below some extremely high temperature, the field ...
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How does the Higgs field prevent the electron from going the speed of light?

Both the Photon and the Electron are point-like particles. Most massive particles can be thought of "bound collections of massless particles", but the electron assumed to be a "point particle with a ...
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Could there exist a “locality” field? [closed]

What I mean is (and I'm a layperson on the subject), can there exist a field that pervades the universe - like the Higgs field - that interacts with particles to give them "distance" or "space" ...
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If mass for Higgs boson is given by Higgs field that is a scalar field, what happens if restrict scalars to form a ring and not a field?

Mass of higgs boson is given by Higgs Field. a. Mass is a scalar quantity, not a vector quantity b. Higgs boson is a scalar boson (spin equals zero), not a gauge-vector boson. c. Higgs Field is a ...
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References for Glashow-Weinberg-Salam model

I am looking for reference recommendations on the Glashow-Weinberg-Salam theory of electroweak symmetry breaking. In particular, I am looking for a discussion of the $SU(2)\times U(1)$ gauge symmetry "...
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Bare mass versus the mass form spontaneous symmetry breaking

Consider renormalization in $\phi^4$ theory $$\mathscr{L}=(\partial\phi)^2-\frac{1}{2}m^2\phi^2+\frac{\lambda}{4}\phi^4$$ where $m$ and $\lambda$ are respectively the unobservable bare mass and bare ...
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What if the two Higgs doublet model is proved right? [closed]

Two higgs doublet model predicts five higgs bosons. If five higgs will be found then how it will impact the known physics?
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How a discrete z2 symmetry removes flavour changing neutral current from Two Higgs Doublet Model?

By applying a discrete Z2 symmetry to the theory of Two Higgs Doublet Model it is ensured that fermions of one type couples to only one doublet. But how FCNC is removed by doing so? Because if all ...
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Higgs amplitude mode vs. “spontaneous breaking” of local gauge symmetry

It seems that there are two definitions of the Higgs mode; one primarily used in particle theory, and one used in condensed matter. In the former, we can consider a simple Lagrangian of the form $$ \...
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Theory behind the experimental signatures of Higgs-Boson

As I understand it, the Higgs-Boson itself is unstable and has a transient existence. So, the particle detectors cannot detect it directly. Instead, the detectors register all the decay products and ...
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How can the Higgs field “sense” that the temperature is high enough to restore the broken symmetry above this temperature?

In the picture below of the potential of the Higgs field, we can see that the field has its highest energy if the field is zero, i.e. if no Higgs particles are present. The symmetry is restored at ...
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Higgs Mechanism in Landau-Ginzburg approach

I'm experiencing some troubles with one of the exercises in Kardars book on Statical physics of fields (problem 5 Ch3) or see https://ocw.mit.edu/courses/physics/8-334-statistical-mechanics-ii-...
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Higgs Field before or after Cosmological Inflation?

Question: When exactly did the Higgs Field begin to exist (before cosmological inflation or after cosmological inflation)?
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What problems arise when mass is introduced as a parameter in Quantum Field Theory instead of through the Higgs Mechanism? [duplicate]

https://www.youtube.com/watch?v=Ni-Lf1y51Dc I always wondered why mass is not considered as a fundamental feature of particles, but instead it is explained through the Higgs mechanism. I am aware of ...
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Custodial Symmetry in SM Higgs

this excercise is about the custodial $SU(2)_R$ symmetry in the SM Higgs Mechanism. Step by step I have to develop the theory. I get the generel idea of the global custodial symmetry and why we need ...
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2Higgs Doublet Models: Mechanism to set Yukawa Couplings to 0?

I just started having a look at 2 Higgs Doublet Models (2HDM) and came across this: The general idea seems pretty simple. Introduce a second Higgs doublet that acquires a vev. The general Yukawa ...
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Dark Matter Wave Particle Duality

CERN is looking for dark photons, and they are seeking to look for interactions with the Higgs boson with the dark photon.See link here. So in other words a dark photon - a mediator for dark matter is ...
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Misconceptions in spontaneous symmetry breaking

Spontaneous symmetry breaking occurs when we have a potential like a mexican hat as shown in figure (right) and is unbroken for the potential shape as shown in left figure. Under the Symmetry ...
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Difference between expected $p_0$-value and observed $p_0$-value?

In the ATLAS paper for the higgs discovery, they used 2 kinds of different $p_0$-values. One is the expected $p_0$-value, the other one is observed $p_0$-value. What's the difference between the ...
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How does one calculate branching ratio of Higgs particle decaying into virtual particle?

Very often when people talk about decay they use branching ratio to describe a particular decay channel, for example: $$Z\rightarrow e^{+}+e^{-}$$ If both Z and the electron and positon are one-...
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Why does the reconstructed mass of a particle have a fairly wide distribution?

In HEP experiments, a particle of interest (e.g. Higgs) is reconstructed using information about decay products, momentum, energy deposits, angle of those particles, etc. The invariant mass of the ...
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How are branching ratios for the Higgs boson calculated?

I'm somewhat familiar with how to calculate branching ratios. I know that they are calculated as the ratio between the decay width of a specific decay process and the total decay width of the particle ...
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Mass of the mesons in a universe with massless quarks

As I propose in this post, About the mass of the particles, imagine a universe with massless quarks due to Higgs' VEV is exactly zero. In our universe, where quarks are massive, we have consider ...
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If the gauge symmetry is not broken by spontaneous symmetry breaking, what symmetry is broken?

In this post, the answer by buzhidao showed that the $U(1)$ gauge symmetry is not broken by spontanous symmetry broken and Higgs mechanism. What role does "spontaneously symmetry breaking" ...
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Why do we conclude $SU(2)\times U(1)$ is broken into $U(1)_{em}$ when local gauge symmetry is not broken?

Recently, I spent some time reading some articles on the concept of SSB and I found that after SSB the local gauge symmetry will not be broken.What are broken are the global symmetries by non-zero VEV ...
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About the mass of the particles

Studying Higgs mechanism in EW theory and QCD I have a couple of questions that I would like to clarify: 1) The quark mass term in QCD Lagrangian should come from Higgs mechanism in EW sector of SM. ...
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Could there be observable gravitational warnings of an approaching vacuum decay bubble?

I understand both gravitational waves and a hypothetic vacuum decay bubble travel with the speed of light. Does this mean there won't ever be any observable warnings of vacuum decay before an ...
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Branching fractions for the 125 GeV Higgs boson

Calculating the branching fractions of a Higgs boson $m_h=125\,\text{GeV}$ into a muon and an anti-muon, and a $b$-quark and an anti-$b$-quark from the decay formula $$\Gamma=\frac{\alpha_{w}}{8 \...
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Can we use discrete symmetry in order to generate neutrino mass in two higgs doublet model?

It is seen that an u(1) symmetry is generally used to explain the seesaw mechanism for neutrino mass in 2HDM.it is used because the theory then naturally predicts the existence of a right handed ...
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Questions about the Higg's Field

Why do some particles interact more strongly with the Higgs field than others, while some particles like the photon do not interact at all? Is there a Higgs number assigned to all particles?
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What is the origin of neutrino mass? [duplicate]

Standard model shows zero mass for neutrino and seesaw model explains why the neutrino mass is so small. But to show that the neutrino mass is small, the mass should be originated by some mechanism. ...
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Can someone explain Technicolor?

I read Wikipedia on Technicolor (and understood some of it - I am not a scientist) Can someone give me a layman's definition? Is the technicolor theory dead now that the Higgs has been found? Can ...
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Hierarchy problems: calculating the mass of the Higgs vs. other SM particles

While reading up on hierarchy problems in particle physics (wikipedia), I stumbled onto the statement that in the Standard Model, there is no hierarchy problem (or at least it cannot be formulated) ...
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What is the relationship between Gravity and the Higgs Field/Higgs Boson? [duplicate]

During a talk with my friend, I came up with a question that seemed to spawn too many sub-questions, none of which we could find the answer to online. Nowhere. The [important] questions are: Since ...
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How much of the proton's mass is due to the Higgs field?

The proton mass is 938 MeV. People often claim that (A) The proton is a bound state of two up quarks and one down quark, with the three quarks contributing a total rest mass of $2 \times (2.2 \text{...
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Why do we need a two-Higgs doublet model and why only one extra doublet is added to the extension?

The general two higgs doublet model can neither give masses to neutrinos without considering a see-saw mechanism nor it can unify gravity with other three forces. To explain dark matter also we have ...
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Masssive mediator boson, a game changer, so is the weak force fundamentally different from the other forces?

I have read this question: How it is possible to mediate a weak interactions by very heavy particle such as Boson? How can a pion have a mass, given it's a "field mediator" and ...
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Could electroweak interactions derive from higgsing of gauged chiral symmetry?

A recent question discussed the practice of introducing electroweak interactions into chiral perturbation theory by gauging part of the chiral symmetry. Gauging chiral symmetry is normally regarded as ...
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What determines the specific value of the order parameter in spontaneous symmetry breaking?

Three examples in the spontaneous symmetry breaking that occurs at a phase transitions: A ferromagnet below the Curie temperature chooses an axis of quantisation along which all the spins align, ...
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Does Higgs Boson influences with Gravity?

Does Higgs Boson influences with Gravity? Is there any way that if the universe is expanding Higgs particle has influence over it?
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Why is Higgs Field a scalar field?

I am reading the book ‘Introduction to Particle Physics’ by Martin and Halzen. In the section about the Higgs Field the book considers the scalar field that interacts with a vector field. Using ...
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Why isn't superconductivity destroyed by the Goldstone modes?

In BCS theory they break particle number conservation and show the existence of a gap, which would explain why groundstate properties stay relatively the same even for higher temperatures (until beta ...
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A couple of questions about spontaneous symmetry breaking (SSB)

I have a few doubts about my understanding of spontaneous symmetry breaking. To keep it simple, I will take a global U(1) transformation on a complex scalar field as an example. The questions are ...
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Lepton flavor violating process on loop level $\mu \rightarrow e \gamma$ via Higgs, Divergent integral

I am stuck with calculating the proces $\mu \rightarrow e \gamma$ as in this diagram: I wrote down the matrix element like this: $$ \mathcal{M}=\bar{u}(p-q)\left[\int \frac{d^4k}{(2\pi)^4}A\frac{(k+...
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Why do we need the two higgs doublet model? [duplicate]

Why do we add an extra doublet to the two higgs doublet model?I mean what are the conditions due to which we had to add an extra doublet. What are the limitations with only one doublet and how 2HDM ...