4
votes
1answer
90 views

Symmetry factor and coupling constant in scalar field theory

I am just now starting my particles "education" so forgive me if this is elementary... Looking at interaction terms in a scalar field Lagrangian, I get: $$ ...
0
votes
0answers
73 views

An electron is an excitation of the electron field. So when we observe a higgs boson that means we've excited the higgs field?

See this related question: If particles are excitations what are their fields? I ask this question because, according to a lecture, the higgs boson was frozen into a "matrix" at some point before ...
1
vote
1answer
86 views

Why doesn't the photon have mass? The Higgs mechanism and pre-electroweak epoch

1) When electroweak separation occurred, 'why' wasn't the photon 'given' mass like the W and Z bosons? i.e why don't photos interact with the higg's field? 2a) How well is the higg's mechanism ...
2
votes
1answer
60 views

Scalar Particles, Flavor Changing Processes and Gauge Symmetries

Let's consider an extended version of the Standard Model (SM) with a new Yukawa operator of the form $$ \sum_\ell g_\ell\bar{\ell}\ell \phi ,$$ where $\ell$ is any lepton of the SM and $\phi$ is a new ...
3
votes
1answer
142 views

Is the Higgs Boson a Force Carrier? [duplicate]

I am told there are four fundamental forces, and each of these forces has a boson that acts as its carrier. Reading this http://www.fnal.gov/pub/science/inquiring/questions/higgs_boson.html I find ...
0
votes
2answers
81 views

Does yukawa potential of two particles have effect on each other? [closed]

Okay,a novice here.Suppose two particle interact with Higgs field.Does The Yukawa potential created by each of them affect each other or the interaction in any way.If so,what is it physical ...
2
votes
1answer
62 views

Importance of the Higgs field being formulated in quantum gauge theory

As far as my knowledge goes, Higgs field is only currently formulated in term of classical gauge theory. What is the importance of Higgs field being formulated in term of quantum gauge theory? In ...
5
votes
0answers
39 views

Finite corrections to the Higgs mass in SUSY

I am worried here about specific supersymmetric scenarios in which an energy scale above the TeV is introduces. An example would be the Seesaw extension of the Minimal Supersymmetric Standard Model. ...
1
vote
2answers
59 views

Higgs doublet: a charged and a neutral component?

In the book 'Modern Particle Physics' byM. thomson the Higgs doublet is written as $$\phi = \left(\begin{matrix} \phi^+ \\ \phi^0 \end{matrix}\right)=\phi = \left(\begin{matrix} \phi_1 +i\phi_2 \\ ...
8
votes
0answers
88 views

Monopoles and the magnetic Higgs mechanism

In a paper of 't Hooft about the rôle of magnetic monopoles for a model of quark confinement, I don't understand the following sentence (end af paragraph 14) [...] in order for monopoles to ...
6
votes
0answers
94 views

Is the Higgs bare mass larger than the physical mass?

The Higgs boson propagator can be written $$\frac{1}{p^2-m^2+\Sigma(p^2)}$$. If we take $p^2=m_P^2$ the physical mass, we get $m_P^2=m^2-\Sigma(m_P^2)$. Now, if $\Sigma\sim \Lambda^2$, we get ...
3
votes
2answers
124 views

Scalar field divergent mass correction interpretation question (hierarchy problem)

Simple power counting tells you that a scalar field coupled to some fermions at one-loop picks up a correction to the mass of the order $\Lambda^2$. Based on this people say things like "it's natural ...
4
votes
2answers
106 views

Higgs mechanism and neutral fields

Consider a Lagrangian $L(\phi,A_{\mu})$ with $\phi$ being some scalar field and $A_{\mu}$ some dynamical U(1) gauge field that minimally couples to $\phi$. Under a global U(1) symmetry the field ...
4
votes
1answer
79 views

How use the Higgs branching ratio plot to extract information about the Higgs mass compared to experiment?

What does the plot of higgs branching ratio (see figure below) say about the higgs mass anyway? How can one use it as a guide to find the higgs mass experimentally? If we e.g. go to $M_H=126$ GeV ...
1
vote
1answer
169 views

What is the meaning of the negative vacuum expectation value of the Higgs field? Do we see it in nature?

In studying about the Higgs field and related, I find little mention of the equilibrium point at -V. I would like help conceptualizing what a negative vacuum expectation value is, ideally with respect ...
1
vote
1answer
103 views

The self-coupling constant for the Higgs mechanism

I have a few questions about the parameter $\lambda$ in the Higgs-Lagrangian density $$\mathcal{L}_H=(D_\mu \phi)^\dagger D_\mu \phi + \mu^2\phi^\dagger\phi-\lambda(\phi^\dagger\phi)^2$$ Is it ...
11
votes
3answers
261 views

Effect of linear terms on a QFT

I was always told when first learning QFT that linear terms in the Lagrangian are harmless and we can essentially just ignore them. However, I've recently seen in the linear sigma model, ...
2
votes
0answers
126 views

How does the Higgs Particle Decay?

Background: It is my understanding that the Higgs Boson is a fluctuation of the Higgs field. It also is not very stable and decays into a plethora of other particles. If all other particles interact ...
0
votes
0answers
66 views

What does it mean that the Higgs has a nonzero vacuum expectation value?

What does it mean that the Higgs has a nonzero vacuum expectation value? Are there any other important field with nonzero VEV? How is this related to the 100-orders magnitude wrong prediction?
3
votes
1answer
87 views

Multi-Fermion interactions induced by integrating-out Yukawa-Higgs terms?

Suppose one considers a multi-component free fermions field theory with field $\psi_{q_i}$ with a give global symmetry (such as U(1)). We can say that every component of fermions carry some U(1) ...
6
votes
2answers
199 views

Mass generation by Chern-Simons theory

Why the mass generation via a Higgs mechanism is different from that of Chern-Simons theory? I haven't done any formal course in Quantum field theory,so how do I understand this just having some basic ...
1
vote
1answer
138 views

Higgs maths video Brian Greene

What do you think of the video below? ==> http://www.youtube.com/watch?v=KWj00MCqSxs Is the explanation in this video largely correct, or missing something? Is the mathematical description in the ...
1
vote
1answer
110 views

Higgs field in space around us?

Is the higgs field in space around us? I understand it as that the higgs field has a constant value on every space time point, is that right? And this value is the vacuum expectation value. This ...
4
votes
3answers
353 views

Virtual Higgs boson?

Can particles emit a virtual Higgs boson in a similar manner to the way a virtual photon is emitted?
2
votes
1answer
151 views

When it is said that the Higgs field is a scalar, do they mean Lorentz scalar?

We often hear that Higgs boson is a scalar boson, and that Higgs field is a scalar field. I was always thinking that this means "4-scalar". In other words, it is space-time invariant, .i.e. it's ...
0
votes
1answer
104 views

Is the Higgs particle the final one predicted by the Standard Model? [duplicate]

Are there any other particle predictions by the standard model?
6
votes
2answers
589 views

Why does adjoint representation matter in some field theories?

Recently I am reading a paper about monopoles. In several cases, it seems that writing fields in adjoint representation of the gauge group makes a difference. Once it leads to different group after ...
5
votes
0answers
179 views

Fields with SO(3) diagonal subgroup symmetry

I read about a Higgs field $\vec{\phi}=\frac{1}{2}a\hat{r}\cdot \vec{\sigma}$ (in the context of 't Hooft-Polyakov monopole) with SO(3) diagonal subgroup symmetry consisting of simultaneous and equal ...
4
votes
1answer
89 views

Why does the minimum energy field configuration require the fields to be constant?

I am having a hard time in understanding a well known statement always made in the context of field theory. Background Consider a classical real scalar field theory with Lagrangian density given by ...
3
votes
1answer
144 views

Topological Mass Generation Mechanism

What is the topological mass generation mechanism? And what is its relation with the Higgs mechanism? Can we say that after the discovery of Higgs boson, the topological mass generation mechanism ...
4
votes
2answers
208 views

Local guage symmety implies causality

I read in a QFT book that local gauge symmetry implies causality. Could someone please explain that statement and why it's true? Thank you.
1
vote
0answers
123 views

“Original” coupling constant of the Higgs with the electron, taking into account renormalization

I read Peskin, Schroeder, "An introduction of quantum field theory". Formula (20.100) gives the electron mass after the Higgs mechanism as $m_e=\frac{1}{\sqrt{2}}\lambda_e v$ Here $v$ is related to ...
2
votes
2answers
296 views

Vacuum Expectation Value and the Minima of the Potential

Often times in quantum field theory, you will hear people using the term "vacuum expectation value" when referring to the minimum of the potential $V(\phi )$ in the Lagrangian (I'm pretty sure every ...
7
votes
0answers
246 views

Penrose's Zig-Zag Model and Conservation of Momentum

I was reading through Penrose's Road to Reality when I saw his interesting description of the Dirac electron (Chapter 25, Section 2). He points out that in the two-spinor formalism, Dirac's one ...
2
votes
1answer
193 views

Is the Higgs mechanism needed for Quantum Field Theory?

The NY Times article on Firewalls today has the following paragraph: Quantum field theory is how the world works [quoting a physicist]. It had a major triumph just a year ago, when the Higgs ...
5
votes
2answers
293 views

Higgs vs phonons

Jim Baggott's "Higgs" quotes David Millers' prize-winning one-page explanation of the Higgs mechanism (the one that evokes Margaret Thatcher crossing a room). I've heard that part many times, but not ...
1
vote
1answer
130 views

Mathematical explanation of why Higgs has a vev

If Higgs ($\phi$) is a complex doublet: $ \phi_{1}+i\phi_{2}$ $\phi_{3}+i\phi_{4}$ how do I show that $\phi_3$ has a vev but the others do not? ...
1
vote
2answers
164 views

Higgs boson sources

Every fundamental interaction in Physics comes from "some bosonic field" or "force carrier", according to QFT. We have 4 fundamental interactions(force carriers): Gravity (Gravitons) ...
0
votes
0answers
149 views

Proof of rotational and translational invariance?

If $ϕ^† ϕ$ is invariant under $SU(2) \times U(1)$, a Phys.SE question I recently posted, then does that mean $ϕ^† ϕ$ is invariant under rotations and translations?
4
votes
3answers
347 views

Problems with putting mass on Yang-Mills theory by hand

When Yang-Mills field theory was introduced, a problem is that the gauge invariance can not allow mass for the gauge field. Later people invented spontaneous symmetry breaking and Higgs mechanism to ...
1
vote
1answer
143 views

How do we calculate the Higgs potential? [closed]

What is the Higgs potential and how do we calculate it?
3
votes
1answer
367 views

Why no fundamental force from the Higgs? [duplicate]

I wish to ask whether I understand the following correctly. This universe seems to have six fundamental elementary bosons namely photon $(\gamma),\ W$-bosons$(W^+,W^-),$ gluon$(g),\ Z$-boson $(Z)$, ...
4
votes
1answer
186 views

What if EM or QCD was spontaneously broken?

Suppose that Standard Model Higgs mechanism broke electromagnetism, by e.g. veving the charged component of the doublet, so that the photon was massive with $m_\gamma\sim v$. Could such a Universe ...
4
votes
0answers
104 views

Categorizing solutions to Hierarchy problem

We know that no gauge symmetry can prevent a term $m_\phi^2|\phi|^2$ for a scalar field, and that, given the quadratic loop corrections, the natural scale is $m_\phi \sim M_P$. This is related to the ...
6
votes
0answers
271 views

Calculating the branching ratio of higgs for decay to two photons? [closed]

I need to use the three lowest order Feynman diagrams to first calculate the squared matrix element to put into Fermi's golden rule formula and then from there get the branching ratio of higgs decays ...
14
votes
2answers
275 views

Infrared-free QED and Higgsless standard model phenomenology

This is one of those "what if" fantasy world type questions. I like hard sci-fi so please no "well, you changed one thing about the world so now anything goes." :) What if the Higgs had no vev? That ...
2
votes
0answers
146 views

Field content and symmetry groups of Minimal Composite Higgs Models

I'm trying to teach myself the Composite Higgs Model, both its theory and its LHC phenomenology (particularly the 4DCHM). Unfortunately, I'm struggling; the literature is contradictory and/or omits ...
2
votes
1answer
151 views

How to find the Higgs coupling with a mixing matrix?

It is known that the couplings to the Higgs are proportional to the mass for fermions; $$g_{hff}=\frac{M_f}{v}$$ where $v$ is the VEV of the Higgs field. I'm trying to figure out why this is true ...
4
votes
1answer
60 views

Higgs VEV in terms of measurements on an ensemble?

Let $A$ be a Hermitian operator corresponding to some observable. If we prepare $N$ identical systems in the state $\psi$ and measure this observable in each system, the average of the measurements ...
5
votes
0answers
66 views

axial and vector resonances in composite higgs models

Is there a reason to believe that the axial resonances be heavier than the vector resonances in the composite higgs models? For instance, in http://arxiv.org/abs/0808.2071, to have zero tree level ...