Questions tagged [weak-interaction]
one of the four known fundamental forces of nature and the one responsible for beta-decay radioactivity. The weak interaction is very short-ranged and more weakly coupled than either the strong nuclear force or electromagnetism. At energy scales above the Z mass the weak and electromagnetic interactions are unified (that is subject to a unified mathematical treatment).
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How Fast Can Toponium Form?
I understand that Toponium is only theoretical because the T quark decays too quickly.
My question is this, would a right handed T quark live long enough to form a meson? If not, how long would it ...
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Help with predicted Pati-Salam model Gauge bosons
The Pati-Salam model is a Grand Unification Theory. However, unlike other ones, it does not propose a unified force and just explains the quirky-ness of the standard model.
It includes a fourth color ...
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How is the chirality for the weak interaction conserved for non-relativistic neutrinos?
In this article, one can read that the neutrinos in the cosmic neutrino background have a speed of about 1/50 of the speed of light, which is clearly non-relativistic.
From the viewpoint of, say, ...
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Electroweak Interaction and SSB
I read that above unification energy, on the order of 100 GeV, electromagnetic force and weak force would merge into a single electroweak force.
I do not really understand how and when exactly two ...
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Gamma Ray Emission in the Wu Experiment
In the classic Wu experiment (https://doi.org/10.1103/PhysRev.105.1413) parity violation was discovered in the weak interaction through the asymmetry in the distribution of electrons in the beta decay ...
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How does parity conservation follow from the Wu experiment?
The Wu experiment shows how parity symmetry does not hold for the weak force. However, how does this proof that parity conservation also doesn't hold?
If my understanding is correct, the absence of ...
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Why are there no particles that ONLY interact via the strong force?
The title speaks for itself really: I noted everywhere I learned about fundamental interactions that there are particles that interact ONLY via the Weak Force (and gravity, if it counts)(e.g. ...
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Is this Why a Neutron can Decay Into a Proton, Electron and Electron Antineutrino?
A neutron is udd, then an u-anti-u starts to exist close to the neutron. Then the one d and u change places forming an uud (proton) and anti-ud which decays to an electron and electron-antineutrino. ...
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Calculation of the decay rate of the $W$ boson
I am trying to calculate the decay rate of the $W^-$ boson to a charged lepton and the corresponding antineutrino.
I denote the four momentum of the $W$ boson with $q = (M_W, \vec{0})$. The momenta of ...
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Two Possible States for Weak Interactions?
Layperson trying to learn particle physics here. For strong interactions, there are three colors (and corresponding anti-colors) which define the possible states of a particle (i.e. quark) for the ...
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Improved estimate of density of free neutrons in solar core
In an answer to this question:
Free neutrons in the sun's core?
I made a very rough attempt to estimate the density of free neutrons in the solar core. There is some non-zero rate for production ...
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Isn't weak interactions necessarily violate strangeness?
The electron-proton elastic scattering process $$e^-+p^+\to e^-+p^+$$ can take place either via a photon exchange (electromagnetic interaction) or via $Z^0$ exchange (weak interaction). But isn't weak ...
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How is this equation about pion decay derived?
I'm reading Peskin's Concepts of Elementary Particle Physics and these equations confuse me.
What are the $\pi^1$ and $\pi^2$ in (15.49) and why $\pi^-$ equals to this?
I don't understand the ...
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How do we prove that hypercharge is different for singlets and doublets?
I am trying to teach myself about the standard model and I am stumped by this point.
I understand that:
When picking an U(1) generator for SU(2)xU(1), any multiple of the identity will do ($YI_n$)
...
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$\beta^{+}$ and $\beta^{-}$ decay processes
We know that electron cannot exist inside the nucleus for various reasons like its energy, angular momentum violation and etc. But these $\beta^{+}$ and $\beta^{-}$ processes occurs inside the nuclei ...
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Why is $\beta$ decay a weak force interaction?
In my graduation and also in post graduation, I was told that $\beta$ decay is a weak interaction. But till date I don't know the reason as if why it is a weak interaction process. In my classes some ...
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Non-leptonic weak decay with $|\Delta T=3/2|$ suppression (from "Inward bound" Pais' book)
In Abraham Pais' "Inward Bound" book at page 564 it is mentioned that if we describe the weak interactions with the usual current-current interaction (including Cabibbo angle) we still do ...
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Has Anti-beta decay been observed?
I am looking for references or resources regarding the transition of an anti-neutron through weak decay, into an anti-proton, positron, and electron-neutrino.
Have such studies been conducted or ...
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Parity Violation In The Weak Force
I am having some trouble understanding parity violation in the weak interaction. Specifically, I have been reading about the 1956 Wu Experiment. From what I understand, it is the anisotropic ...
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Is it possible to construct a realistic $SU(2)$ model for the weak interaction despite the failure to introduce full weak isospin symmetry?
In his chapter on the electroweak unification, Griffiths introduces the weak hypercharge explaining that his attempt at introducing full weak isospin symmetry with the Pauli spin matrices failed ...
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Why were weak neutral currents considered evidence for electroweak theory?
For example, Wikipedia says:
The existence of the electroweak interactions was experimentally established in two stages, the first being the discovery of neutral currents in neutrino scattering by ...
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Is there any something something force other than the electro magnetic force?
Far as I can tell, the force generated by electromagnetic field can be seen as an electrical force or as a magnetic force depending on the observer, i.e., these forces are actually the same phenomenon ...
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Is weak hypercharge carried by $Z$ boson?
In the PBS spacetime video about charge (https://www.youtube.com/watch?v=esayi49OAk4), at 10:55 he said that weak hypercharge is carried by the $Z$ boson. Is this accurate?
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QFT symmetry breaking and CP violation
Since the weak interaction violates CP symmetry but electromagnetism doesnt,does it mean that the electroweak fields also violates CP symmetry?Can a field which violates some symmetry be the product ...
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What is a CP number? In terms of CP-Symmetry and CP-Violation?
When researching the origins of CP-symmetry and CP-violation, and the Fitch-Cronin experiment demonstrating 'indirect' CP-violation, I came across these statements:
https://www2.lbl.gov/abc/wallchart/...
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Is crossing symmetry violated in the difference between positron emission and electron capture?
As discussed in the relevant Wikipedia article, beta decay via electron capture is possible in circumstances when positron emission is not.
From a simple (and perhaps naive) point of view, the two ...
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Fixing $CP$ phases to cancel CKM phases
When we try to see if the weak sector is $CP$ invariant, we $CP$ transform all the fields in the charged interactions terms and we get a condition involving the elements of the CKM matrix and the ...
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Can the weak isospin of elementary particles be measured experimentally or is it penciled into the Standard Model?
The chart below from Wikipedia lists the weak isospins of all elementary particles.
It states that right-handed matter particles and left-handed anti-matter particles have a weak isospin of 0.
Is ...
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Why are interactions mediated by the $W$ bosons and the $Z$ bosons classified as a single type of force when they are so different?
We always hear of 4 Forces or interactions, i.e. the Strong Force, Electromagnetic Force, Weak Force and Gravity. Each force has its mediating Bosons, i.e. gluons for Strong Force, photons for ...
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Additional fundamental forces induced by (unknown or not) massless fermions?
Just thinking about one stupid question: what if there are some massless fermions we don't have detected by some reason and they have interactions (related or not with the weak force and the Fermi ...
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How do I rule out the decay $dss \to n + \pi^{-1}$?
I recently saw a question:
A baryon has quark structure $dss$ and it decays via the weak interaction. Which of the following is a possible decay product?
$\Lambda^0+\pi^{-1}$
$n + \pi^{-1}$
$\Lambda^...
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Could the low Higgs mass be relevant to the unification of the (weak) nuclear force and gravity?
I found in a paragraph in a research paper (although it was talking about something else) the statement: that it is possible to unite the weak nuclear force and gravity, but that requires that:
Both ...
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When is the weak force triggered? [closed]
I've been trying to understand the weak force (very much at a layman's level), and I've seen a lot of descriptions that say more or less the same thing. But I've had difficulty tracking down an answer ...
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If there wasn't a weak nuclear force, what would be the heaviest stable theoretically stable isotope with equal protons and neutrons?
If there was no weak nuclear force, what would be the heaviest stable theoretically stable isotope with equal protons and Neutrons? For our universe the heaviest such isotope is calcium 40, but most ...
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What causes the difference in ranges of forces?
What causes the difference in ranges of forces? In other words, why is it that the weak force acts only at small distances whereas the Coulomb force has a very large range?
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Why is Astatine-210 (At-210) the longest-lived isotope of astatine despite possessing an odd number of neutrons?
I am guessing that isotopes with an even number of neutrons more readily release an alpha particle... When and if At-210 does that, it still has the problem of being 'odd/odd'...
But this begs the ...
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What quantities are associated with the strong and weak forces?
If mass is the quantity associated with gravitation, and charge is the quantity associated with the electromagnetic force, what quantities are associated with the strong and weak forces?
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Can there be bound states of two $Z$ bosons or of a $W^+$ and a $W^-$ boson? [duplicate]
Obviously, the Z and W are extremely short-lived.
But could they form bound states?
Such bound states would be the weak analogon of glueballs.
Have they been studied? Or is beyond-standard-model ...
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Why is $W$ boson decay into more than 2 particles not possible?
I am studying hadronic decay of the $W^-$ boson. I am aware that the decay into quarks from different generations is not possible and that charge as well as the total angular momentum have to be ...
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Can a positive $W$ boson and negative $W$ boson exchange a lepton, and release a charged lepton antilepton pair or neutrino antineutrino pair?
Would it be possible for two passing $W$ bosons with opposing charge to either release a neutrino and become the corresponding charged lepton and charged antilepton, or release a charged lepton, and ...
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Can an electron "annihilate" with something other than a positron?
Processes like the electron-positron annihilation are widely known and they give us the impression that "matter annihilates with antimatter." However, I am wondering if this repeated phrase ...
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Evidence of neutral weak currents
Why is muonic anitneutrino, electron scattering an experimental evidence of the existence of neutral weak current? This is $\bar{\nu_{\mu}}+e^-\to \bar{\nu_{\mu}}+e^-$.
And why the electron ...
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Antimuon-electron interaction
I was wondering if the following interaction is possible:
$\mu^++e^-\to \bar{\nu_{\mu}}+\nu_e$
Clearly every conservation law is satisfied, including each lepton number conservation, but I can’t seem ...
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GIM mechanism and $K_L$ decay
I'm trying to solve the problem (14.5) of Introduction to Nuclear and Particle physics by A. Das and T. Ferbel.
What am I trying to do is to prove that $\langle Z^0|d\bar{s}\rangle = 0$ by ...
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How to use the quark model to explain that the $D^+$ won't be a strange particle?
For the system of $K^-,\pi^+,\pi^+$, with the invariant mass spectrum peaking about 1.87 GeV, call this resonant peak $D^+$; we find its spin to be zero by experiment.
Using the quark model, how ...
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What is the effect of top quark on Flavor Changing Neutral Current (FCNC) suppression?
We know that the introduction of charm quark (GIM mechanism) suppresses Flavor Changing Neutral Current (FCNC) decays occuring via Electroweak box and penguin diagrams. But we have another doublet of ...
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D-6 Term and Spontaneous Symetry Break
I'm reading a text https://arxiv.org/abs/1008.4884 about D-6 operators in Standard Model extensions.
One term we can add to our lagrangian is
\begin{equation}
\mathcal{Q}^{(1)}_{\varphi l} = (\varphi^{...
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Chirality in muon decay
Consider the muon decay process:
We assign the chirality according to the $W$ boson current: (i.e. P&S eq.(20.80))
$$J_W^{\mu+}=\frac{1}{\sqrt{2}}\bar{\nu}_{\mu L}\gamma^{\mu}\mu_L \quad J_W^{\mu-...
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Peskin QFT eq.(20.80) derivation
In the derivation of electroweak current (P&S eq.(20.80)), we start with
$$\begin{equation}
\mathcal{L}=\bar{E}_L(i \not D) E_L+\bar{e}_R(i \not D) e_R+\bar{Q}_L(i \not D) Q_L+\bar{u}_R(i \not D) ...
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How does the factor $m_b$ arise in the weak effective operator $\mathcal{O}_7^\gamma$?
According to [1] one of the dominant operators contributing to the decay $B \rightarrow K^{(*)} \ell^+ \ell^-$ is given by $\mathcal{O}_7^\gamma$.
When calculating the coefficient of this operator ...
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