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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Unitary Gauge transfomation [closed]

Consider the following lagrangian $$ -\frac{1}{4}tr(F^{μν}F_{μν})+\frac{1}{2}\overline{(D_μφ)}D^μφ - V(φ)$$ Where $F^{μν}$ is an $SU(2)$ field strength tensor and $φ$ is a complex scalar doublet, ...
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Does the Higgs mechanism work through virtual Higgs bosons? [duplicate]

I read a number of articles, but couldn't find the answer. How does the Higgs mechanism work? doesn't answer my question - it doesn't even contain the word virtual.
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In Standard Model, are both the Higgs doublet and its complex conjugate present in the universe, or not the complex conjugate one?

In Standard Model, the Higgs doublet is \begin{equation} \Phi=\left(\begin{array}{c}\phi^+\\ \phi^0\end{array}\right) =\frac{1}{\sqrt{2}}\left(\begin{array}{c} \phi_1+i\phi_2\\ \phi_3+i\phi_4 \end{...
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Do $Y$ bosons gain a little bit of mass from Higgs of $\bf 5$ rep in $SU(5)$ GUT theory?

I know that when the Higgs in the 24 rep takes a v.e.v. of this form $$v_{24}\,\mathrm{diag}\begin{pmatrix} -\frac{2}{\sqrt{15}} & -\frac{2}{\sqrt{15}} & -\frac{2}{\sqrt{15}} & \frac{3}{\...
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Are the particles in electroweak SSB composite?

The energy scale of a universe containing the electroweak interaction and the Higgs field only is the average energy of the fields $W^1, ​​W^2, W^3$, $B$ and the Higgs field. If electroweak bosons ...
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Was combing gauge fields into photon and $Z$ boson already considered before incorportating Higgs mechanism in Standard Model?

Before physicists had the idea to incorporate the Higgs mechanism in the Standard Model, was there already the idea to combine the gauge fields $B_{\mu}$, $W_{\mu}^1$, $W_{\mu}^2$, $W_{\mu}^3$ into $$...
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Does $CP$-violation mean $CP$-odd?

This might be a very simple question but I'm doing some reading into the Higgs boson and $CP$-symmetry breaking. I've seen the terms $CP$-even and $CP$-odd terms in the Hamiltonian floated around and ...
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If we had a Higgs triplet with hypercharge $Y=1$, would we get three Higgs bosons?

In the Standard Model, the Higgs field is a doublet of SU(2) and hypercharge $Y=1/2$. We have four real scalar degrees of freedom (since $H$ is a complex doublet); three of these get "eaten" ...
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What are thought to be causes of the Mexican hat potential?

We all know the shape of the Mexican Hat Potential. It even serves as site logo. It's a weird potential that has an actual existence in condensed state physics. It's for sure a possibility, and ...
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Do Higgs fields commute with $W^1$, $W^2$, $W^3$, $B$, and why?

In Standard Mode, we have quantities such as : $\left(D_{\mu}\Phi\right)= \left( \begin{array}{cc} \partial_{\mu}+i\frac{g}{2}W_{\mu}^3+i\frac{g'}{2}B_{\mu} &i\frac{g}{2}W_{\mu}^1+\frac{g}{2}W_{\...
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How (if) are the Higgs scalar and the $W/Z$ vectors related (apart from interaction)?

An idea popped up in my mind. There are three vector bosons, the two charged $W$-particles, and the $Z$-particle, all three with spin 1. Is the Higgs particle, having spin 0, related to them, apart ...
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Are the particles in the zero-energy Higgs field real or virtual?

We all know that in particle physics the vacuum state is the state with no real particles. Unless the vacuum has the least energy with particles, because the degenerate vacuum, lowest energy state ...
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What is wrong with the dependence of result with the order of the operation in my computation of Higgs sector derivative term?

In Standard Model Higgs sector, there are terms that introduce : $\left(D_{\mu}\Phi\right)= \left( \begin{array}{cc} \partial_{\mu}+i\frac{g}{2}W_{\mu}^3+i\frac{g'}{2}B_{\mu} &i\frac{g}{2}W_{\mu}^...
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What is the mathematical expression for the Higgs boson coupling constant?

I have been searching around and cannot get an expression for the Higg's coupling constant. By 'coupling constant', I mean for the strong force $$\alpha_S=\frac{{g_S}^2}{4 \pi \hbar c}\approx 0.1\tag{...
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Why is the decay channel $H \to \gamma\gamma$ direct evidence that the spin of the Higgs must be different from one?

The title says it all really, I searched this website and came across a post with a question titled Why is the Higgs boson spin 0?. But it doesn't really answer my question in the title. But this next ...
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Higgs field has no charged component, how do we justify this?

I've recently learnt about EW symmetry breaking. For the weak isospin doublet higgs field, $$\phi=(\phi^{+}, \phi^{0})$$ We have a vacuum state where $|\phi|=v/\sqrt{2}$, for the vacuum expectation ...
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Does the Higgs field have an energy?

I have many questions about the notion of space. I learned that at the quantum level, energy became quantized and that the infinite sum of energy states can no longer be substitued by integrals (...
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Tadpole VEV from a fermion loop?

We have one extra complex scalar $\Phi$ beyond the Standard Model (BSM) protected by an $U(1)$ global symmetry, which is broken by an Yukawa coupling $ y_\Phi \Phi \overline{\chi} \chi$, where $\chi$ ...
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How can a flavour changing neutral current be drawn for the higgs decay to two down-type quarks?

I am trying to draw a Feynman diagram for the decay $ h \rightarrow d+\bar{s} $, but I'm struggling to create one which makes sense. So far I have this diagram: . Please could someone explain what is ...
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Two questions about the Higgs decay mode graph

I have two questions reading this graph which shows the Higgs decay mode: I know the mass of Higgs bosons is measured to be around 125 GeV, which is the solid line on the graph, so I wonder why could ...
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Is the mass of Higgs bosons measured only through the decay into photons?

I'm reading an essay discussing the measurement of Higgs boson mass: https://cms.cern/news/cms-precisely-measures-mass-higgs-boson, which says that the latest and more accurate measurement results ...
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How can I interpret this result of Higgs boson decay?

I'm reading this webpage which introduces the idea of measuring the mass of Higgs bosons with high precision: https://cms.cern/news/cms-precisely-measures-mass-higgs-boson . They presented this ...
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Can Higgs particles move faster than the speed of light in the high energy (temperature) regime? [duplicate]

In the standard model, Higgs particles have negative mass squared term in the SM lagrangian and hence, the Higgs is tachyonic in nature. This isn't a problem since -at low energy (temperature)- the ...
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Standard Model $\rho$ parameter with changing Electroweak gauge symmetry

In Standard Model Electroweak Theory (Governed by $SU(2)_L$ gauge symmetry), $\rho$ parameter is defined as $\frac{M_W^2}{M^2_{Z^0}\cos^2{\theta_w}}=1$. Where $M_W$ and $M_{Z^0}$ are the SM $W$ and $Z^...
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Would it be possible to utilize the higgs boson field in order to generate more inertia?

Since the Higgs boson provides mass would it be possible at all to use the field in a way that generates more inertia? For example, could we utilize it in a way to make a vehicle or something smaller ...
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How could negative $W$ "eat" the positive Goldstone bosons $\phi_1$ and $\phi_2$?

In the Standard Model, the Higgs field is $\Phi=\left(\begin{array}{c}\phi^+\\\phi^0\\\end{array}\right)=\frac{1}{\sqrt{2}}\left(\begin{array}{c}\phi_1+i\phi_2\\\phi_3+i\phi_4\\\end{array}\right)$. ...
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In simple English what is meant by "tagging", "triggering", "selection criteria" and "reconstructed events/particles/masses" in particle physics? [closed]

I am currently reading the original Higgs boson discovery paper, "Observation of a new boson at a mass of $125$ GeV with the CMS experiment at the LHC", HIG-12-028, which can be found ...
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What does the Spontaneous Symmetry Breaking with Higgs Mechanism imply effectively?

Suppose it is understood how the Spontaneous Symmetry Breaking work mathematically to give masses to Fermions through Yukawa Interactions and to Gauge Bosons via Higgs Mechanism. In this case, my ...
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Doubly-charged scalar decay and spinors

In the minimal type-II seesaw, in addition to the SM Higgs doublet $\phi (\phi^+,\phi^0)^\top$, one introduces a complex $SU(2)_L$ scalar triplet that can be written as $$\Delta_{L}=\left(\begin{array}...
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How to identify which particles can run in the loop for Higgs decays to gluons and photons

I am following the lecture notes given in "Higgs physics within and beyond the Standard Model" by HE. Logan and on pages 21 to 24 she discusses Higgs boson decays to photons and gluons which ...
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How to estimate the experimental acceptance of a particle as a function of its life-time?

My lecturer stated that we can calculate the experimental acceptance of the Higgs boson as a function of the life-time and also as a function of the mass by reading the following article: Davier and ...
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How are signal strength modifiers calculated?

I've been asked to measure a likelihood function , and to measure "simultaneously parameters" $\mu^{ggF}$ and $\mu^{V \hspace{0.5 mm} BF} $ , and to measure the parameters $\mu^{ggF}$ and $\...
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Why is the Yukawa interaction term for Higgs coupling to quarks the way it is?

The term for Yukawa coupling between the Higgs and down quarks is given below. $$ \mathcal{L} = -(y_{e}\bar{d_{R}}\Phi^{\dagger}Q_{L}) + h.c. $$ My question is why does it take this form? Specifically,...
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Higgs particle elementary? [closed]

The Higgs boson was observed in 2012 and is known to be a fundamental particle in the standard model, but it could be that it is not fundamental/or it consists of other particles? So my question is, ...
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Why do we have distinct generations of fermions, rather than a continuous distribution of fermions with increasing mass? [closed]

As far as I am aware, each generation of fermion varies only in mass, thus my question is why do we have only three distinct generations of fermion, instead of a continuous mass spectrum of particles ...
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Why is there an upper mass limit of $300$ GeV of the Higgs boson for $W/Z$ associated production and t$\bar{\mathrm{t}}$H associated production modes?

I am currently trying to understand this graph for the cross-section versus Higgs mass: As you can see from the above graph, there is an abrupt cut-off at $M_H=300$ GeV where I have put a green box ...
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How does the Higgs being a Goldstone Boson (in new models) protects its mass from quadratic corrections?

I understand how a symmetry protects a mass from this type of correction: It is known that a symmetry is not broken by corrections of any order -- this hints that if a mass term is forbidden by an ...
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Composite Higgs $SO(5)\to SO(4)$ model: how is $H$ a composite particle?

I am reading this review on CH models by Wulzer and Panico. In Section 2.2.2, they write a minimal model of $SO(5)$ breaking into $SO(4)$, triggering electroweak symmetry breaking (EWSB) with a ...
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Are there in nature any Right Chiral isolated electron particles?

Note: I refrain from using the concept of handedness and the terms left-handed and right-handed when referring to chirality since these usually refer to the helicity of charged fermions and their ...
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Why is the electron massless before interaction with the Higgs field?

Can't the electron have a mass before electroweak symmetry breaking, which is then just modified by its interaction with the Higgs field, instead of gaining all its mass this way? Apparently other ...
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Why is the branching ratio $H\to WW$ much larger than $H \to ZZ$?

The Higgs decay to a pair of W bosons is the second-largest ($\mathrm{BR}(H\to WW)=21.8\%$), while the one to $Z$ bosons is so much smaller ($\mathrm{BR}(H\to ZZ)=2.7\%$). Is there an obvious reason ...
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Physical interpretation of changing phase around the Higgs potential

Disclaimer: I don't know much detail about the Higgs except for a few basic points. The field can be written as $$\phi(x) = \Phi e^{i\Theta(x)}$$ Which I took from the Wiki. I think I can see how the ...
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Is the Higgs force a contact scalar "force" delivering mass only (so no momentum)?

The Higgs force is not a gauge force like constituted by photons. It's not an intermediating field but a field that interacts directly with particles, without a gauge field to mediate its presence to ...
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What are the Higgsless Theories that can explain the Higgs boson detection at the LHC?

As many know, in 2012 the Higgs Boson was "detected" at the LHC. I have read that the Higgs boson was not actually directly observed, but the existence of the Higgs boson in the standard ...
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How (if) are the spontaneous symmetry breakings of the Higgs field at different locations correlated?

I don't know what it is, but no one seems to be able to give a satisfactory answer about the how of the mass generation in the Higgs mechanism. The amplitude of the Higgs field falls into the rim of ...
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How does the Higgs field decelerate particles that travel at the speed of light?

The Higgs mechanism is supposed to give mass to most particles in the standard model. The Higgs field has a positive VEV. The Mexican Hat potential is the visible expression. When the field is zero, ...
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Intuition/Motivation behind necessity of Spontaneous Symmetry Breaking to generate massive gauge bosons

In field theory textbooks, it is shown that while any gauge invariant Lagrangian must involve massless gauge fields, to obtain massive gauge bosons, we must postulate the existence of a Higgs scalar ...
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Why are Yukawa couplings regarded as fundamental constants if their values vary with scale?

Why are Yukawa couplings regarded as fundamental constants if their values vary slowly with the energy scale (distance scale) at which they are measured? This question is the same as why are quarks ...
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Higgs boson propagator and current terms

I have been trying to get the scattering amplitude for $u+u \rightarrow u+u$ where $u$ are a specific type of lepton. From the following diagrams, I can write the Feynman amplitudes as $$\mathcal{M_1} ...
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MSSM interactions

I have seen many pictures of fermion-boson interactions. But none of them are related to gravitons and MSSM particles. Do gravitons interact with photons, gluons and other particles? What about the 4 ...
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