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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136 views

Are neutrinos diffused or defracted by the moon?

We all know that neutrinos pass directly through things, even big things such as the earth. However it is also known that neutrinos interact with matter as a result of the Z boson or neutral current. ...
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Conditions of validity of Sargent rule?

In Perkins (2000, link to Google Books) the following statement is made about Sargent rule: Discovered empirically in nuclear $\beta$-decay, but applicable to any three-body weak decay, ... (pg 405 ...
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Could there be a force between the weak and strong forces? [closed]

Could there be a force between the weak and strong forces? Is possible to switch from one force to another or is mandatory to use the Higgs Field as like a monitor/projector of the 4 forces? The ...
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Can't the weak force be explained purely by electrostatics?

Again, super naive, but my basic question is: isn't the force of attraction between electrons and protons sufficient to explain their confinement to atomic orbitals. I know the W and Z particles have ...
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229 views

Why don't neutron stars transform into proton stars as a result of neutron beta decay? [duplicate]

Free neutrons, as we know them, are unstable and hence undergo a three-body decay into proton, electron and antineutrino with a mean lifetime of just under 15 minutes. But there are astrophysical ...
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Current constraints on Dark Matter self-interaction from galactic profiles

The self-interaction of dark matter may be small but it cannot be negligible if it is able to dissipate energy to relax into galactic clumps (necessary to explain galaxy rotation curves). According ...
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Defining total energy in weak interaction involving a neutrino

This question was inspired by the brief introduction to neutrino oscillations given in a Particle Physics course I took recently and has been bothering me for a while now. I hope to find some ...
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255 views

Working out the charge of a W Boson

When dealing with particle interactions, is there a straightforward way to work out the charge on the W boson? In particular, the interactions I need to know the charge for are those involving a ...
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544 views

How is the weak force important for the Universe?

Once we were talking about the four fundamental physical forces and how to they govern the Universe. There was no problem in understanding the role and importance of the electromagnetic, gravitational ...
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Neutral meson weak interaction

Suppose the quark neutral current weak interaction lagrangian: $$ \tag 1 L = \bar{q}\gamma_{\mu}(g_{V}+g_{A}\gamma_{5})qZ^{\mu}, \quad q = u,d $$ How to derive from this Lagrangian the neutral ...
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Universal Law of Strong/Weak Force? [duplicate]

Okay, first things first, I'm very basic when it comes to the field of physics, but I'm very good at coding, and I was wondering if I could simulate an atom. I know that in order to make such a ...
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Can you shoot a neutrino through Earth?

My dad once told me that he read an article about some physicists wanting to shoot neutrinos through Earth as a way of communication. The explanation to why it would work being that at the atomic ...
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288 views

W+ and Z boson scattering($W^+ Z \rightarrow W^+ Z$)

In Matthew Schwarz QFT textbook on page 588-9, $W^+_L Z_L \rightarrow W^+_L Z_L$ was illustrated but the kinds of weak bosons are absent. The diagram of the problem is as follows: This is s-channel, ...
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What is Weak isospin in Laymans terms?

What is Weak isospin in Laymans terms? I apologise if this is a bit of a basic question but I have read the Wikipedia page and all it says is that it is quantum number relating to weak interaction. I'...
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Does the relation below between the masses of pions imply that the weak force is not a basic force?

In the old theory of the strong nuclear force, this force is transmitted by massive pions. Just as the weak nuclear force is transmitted by massive W- and Z- particles. Is it possible to develop a ...
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What is the weak isospin of hadrons?

What are the weak isospins (T3 values) of various hadrons, including the proton, neutron, mesons, hyperons and other hadrons? How is the weak isospin calculated for any hadron? Published sources ...
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How can K (kaon) and Σ (sigma particle) be created quickly via the strong interaction and decay slowly via the weak interaction?

So the kaon particle (K) and the sigma particle (Σ) are created very quickly through the strong interaction and decay slowly through the weak interaction. How is this so? Is this not some kind of ...
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$SU(2)_L$ Gauge theory and particle-antiparticle annihilation

I have a problem understanding how to reconcile the particle antiparticle annihilation vertex with the $SU(2)$ gauge theory, in the context of the weak interaction. Let me explain better : Invoking $...
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Can quarks of different generations enter a $Z$ boson vertex?

Reading through my particle physics book (Thomson's "Modern Particle Physics"), it appears that when calculating the possible decays of the $Z$ boson, we do not consider decays such as $Z\rightarrow u ...
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Why can't matter anihilate with itself?

I am wondering, in patricle physics, when we have an annihilation vertex, we always have a particle and an antiparticle annihilating. Why is that ? Let me make an example to be clearer. Let's take a ...
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Which of the 4 forces can we practically or theoretically influence?

Obviously we have the ability to create an EM field quite easily as seen in an MRI machine. Do we currently have the ability to control any of the other fundamental forces... One or other of the ...
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What kind of waves can be/are produced by accelerating strong /weak forces [duplicate]

Accelerating masses are now confirmed to produce gravitational waves. Also it is known that accelerating charges (electrical) produce EM waves. But what kind of waves are produced when particles ...
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If weak force causes decay of a single particle, why is it called a force between two particles?

Weak force acts at very short distances (10^-16 to 10^-17 m), but what is this distance ? Is this the distance between two particles that can experience this force ?...
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beta decay form factors

I'm trying to understand formula from Anthony Zee qft in nutshell for beta decay: $$\langle p'|{J_5}^{\mu} |p\rangle = \bar u(p')\left[\gamma^\mu\gamma^5F(q^2) +q^\mu\gamma^5G(q^2)\right]u(p)$$ it ...
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If strong force is not a classical force that attracts and pulls the particles together then why does it keep the particles bound together?

(a) In another answer someone said that Strong force etc are not classical forces that push or pull particles in the classical sense but are interactions between states. If this is true then why ...
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How to interpret Law of conservation of strangeness?

Is there a recent explanation of Law of conservation of strangeness? and why does it not work for reactions taking long times like $10^{-10}$ seconds?
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Standard Model Proton Decay Rate

The electro-weak force is known to contain a chiral anomaly that breaks $B+L$ conservation. In other words, it allows for the sum of baryons and leptons to change, but still conserves the difference ...
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Are quarks in a doublet weak analogues to strong color states?

Quarks and gluons interact so frequently that it makes little sense to regard each color state as a unique fundamental particle. These interactions also do not change any of the quarks' other ...
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Does the top quark decay into an on-shell W boson?

Considering that the top/truth quark is the only quark with higher mass than the massive bosons, is the W boson in its decay different than the off-shell bosons that mediate the weak decay of other ...
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Why must the speed of light be the universal speed limit for all the fundamental forces of nature? [duplicate]

Einstein discovered from studying the electrodynamics of moving bodies, that the speed of light $c_{em}$ is the same for observers, which move relative to each other with a constant velocity. But why ...
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A field for the weak nuclear force

This is a thought experiment, and I seek to learn that this is a silly question. Assume electrons were placed in a plane, and in a parallel plane you were able to confine neutrinos. Given that they ...
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307 views

How were Electromagnetism and Weak interaction unified and proven?

How did the electroweak interaction come into fruition?
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Why can't weak interaction bind neutrino and electron together? [duplicate]

According to wiki, unlike the other three interactions, weak interaction does not produce bound states. However, according to this and this, the weak force should be attractive between particles with ...
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Is weak interaction the only interaction capable of changing the flavor of leptons?

I see this sentence in wiki about weak interaction: It is the only interaction capable of changing the flavor of quarks. So why only quarks? Why not leptons? Is there another interaction which can ...
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The decay of the strange quark via weak interactions?

The strange quark can decay via weak charged currents, following the rule that if $|\Delta S|=1$ then $\Delta S=\Delta Q_H$ where $Q_H$ is the hadron charge. The source below states that an $s$-quark ...
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Why is it so hard to find a heavy right-handed W boson? [closed]

I understand that nobody has detected it yet or perhaps never will, is it because of their short half-life but I thought they cannot decay due to chirality or is it because of engineering limitations ...
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What is the difference between Strong, Weak Force and Electromagnetism? [closed]

I was watching a documentary and they said that the Strong Force is what keeps the nucleus together (Nuclear Force) and Electromagnetism is what causes the attraction between electron and nucleus so ...
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Why does the weak interaction not conserve the flavour quantum number? [duplicate]

The weak interaction, in contrast to the strong and electromagnetic, is the mediator of the decay of the strange quark, purely because the weak interaction is 'allowed' to break conservation of ...
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What could happen if each of the four fundamental forces became stronger or weaker? [closed]

Theoretically, what could happen if: Strong interaction Weak interaction Gravitation Electromagnetism Became stronger or weaker? What would be the observable effects for each, separately?
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Can neutrinos interact by the EM interaction and gravity?

A definition of a lepton is: A particle that does not interact by the strong force but does by the 3 other forces.$^1$ Neutrinos are leptons, so from the above definition one would expect it to ...
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How to understand CP-violation in kaon systems with Feynman diagrams and matrix elements?

I am trying to understand CP-Violation in the Kaon system using feynman diagrams and matrix element. Here is a slide from Mark Thomson corresponding exactly to what I am looking for (http://www.hep....
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Solar activity and radioactive decay rates [duplicate]

I recall hearing about this quite some time ago and thought it was very strange. I recently had it pop in my head again and was curious if anyone knew what was going on with this. Variable decay ...
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How much of the decay energy is left when the electron escapes to large distances?

During a neutron decay, there is distribution of KE of electron. When KE given to electron is $0.782~\mathrm{MeV}$ (max) , it escapes from proton field. A lot of this KE is used for Potential Energy. ...
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Weak decay iff or if strangeness changes? [duplicate]

I know that for a decay if the strangeness changes then the decay is a weak decay because strangeness is conserved in both strong decays and electromagnetic decays. However, is it also true that if a ...
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How it is possible to mediate a weak interactions by very heavy particle such as Boson?

When considering a weak decay interaction such as leptons , the weak force is mediate by huge particle such as bosons (W+ or W- ). How it is possible to have a such heavy particle within less massive ...
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How does the nature of bonding between individual atoms in a molecule affect the van der Waal interactions between molecules?

I am currently studying certain materials. Some of these materials have ionic bonds, while some others have covalent bonds. Moreover, each unit of these materials interacts with the adjacent unit via ...
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Is it possible the weak force isn´t fundamental? [closed]

Once the strong force was thought to be a fundamental force mediated by the massive pion. Later colour and gluons were introduced. The old strong force was a residue force of the new fundamental force....
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How many kinds of “weak charges” exist?

For electricity, we have one charge, for the strong force three. How many are there connected to the weak force? Three, because of the W- and Z-particles? For the weak force, there is the isospin, ...
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Would life (as we know it) be possible without the weak interaction?

I understand why the strong interaction is important in everyday life (it holds nuclei together and also allows the fusion reactions that power the Sun) and also why the electromagnetic interaction is ...
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Change of flavour, Weak interaction

I couldn't find a straight and clear answer to this question on the internet: Why is the weak interaction (charged), the only interaction which can change the flavours of the quarks?