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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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 ...
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Electric charge of the Higgs field

The Higgs field is \begin{equation} \Phi = \left( \begin{array}{cc} \phi_{1} + i\phi_{2} \\ \phi_{3} + i\phi_{4} \end{array} \right) \tag{1} \end{equation} with $\phi_{1}$ and $\phi_{2}$ ...
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Higgs field and Time dilation

I am wondering if the Higgs field is related to time dilation. Photons travel at the speed of light, but muons are very close but never at the speed of light. Would Muons be slowed by the interaction ...
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Charge operator applied to matrix multiplets

In the context of SM ($SU(3)_C\otimes SU(2)_L\otimes U(1)_Y$) the charge operator is $Q_{SM} = T_3 + \frac{Y}{2}\mathbb{I}_2$ and gives us the fermions charges. Here $T_3=\frac{1}{2}\sigma_3$ is the ...
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$W$, $Z$ bozons and fermions gained their masses WHEN?

I have read these questions: How does the Higgs mechanism work? How does the Higgs boson give mass to other elementary particles like electrons? What is the difference between the Higgs Boson ...
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What is $\mathbb{Z}_2$ Parity?

While reading about exotic decays of Higgs boson one of the simplest interaction that we come up with which leads to BSM decays is: $$\Delta L = \frac{\zeta}{2}s^{2}|H|^{2}.$$ This is the ...
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Interpretation of a CLs exclusion plot

I have some trouble with the interpretation of this plot. The plot on the right shows the CLs values for the SM Higgs boson hypothesis as a function of the Higgs boson mass in the range 110–145 GeV. I ...
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Electroweak phase transition and finite temperature field theory formalism

We do our calculations in standard quantum field theory at zero temperature where we can derive pole mass and renormalized mass and ... Due to my understanding, pole mass is independent of any energy ...
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Does two Higgs doublet model predicts two Higgs bosons?

Does 2HDM predict two higgs boson? Why two doublets are needed? I need a simplified answer as i am new to BSM
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Higgs-Mechanism: Why are gauge boson masses not protected by gauge symmetry

In non-spontaneously broken QFT like QED the gauge bosons cannot have a mass due to gauge symmetry (follows from Ward identity). Also they have only 2 polarizations. However in a spontaneously broken ...