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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).

Carrier bosons

The weak force is mediated by the exchange of three massive bosons: $W^{\pm}$ (mass about 80.4 GeV) and $Z^0$ (mass 91.2 GeV).

Conservation laws

Uniquely among the known forces the weak interaction violates flavor conservation in both the quark and lepton sectors, violates parity in purely leptonic interaction and violates charge-parity in some hadronic decay channels.

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How come neutrons in a nucleus don't decay?

I know outside a nucleus, neutrons are unstable and they have half life of about 15 minutes. But when they are together with protons inside the nucleus, they are stable. How does that happen? I got this from wikipedia: When bound inside of a…
Aria
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Weak force: attractive or repulsive?

We are always told that there are the four fundamental forces or interactions of nature: gravitation, electromagnetism, and the weak and strong forces. We know that gravitation is attractive, that electromagnetism can be attractive or repulsive…
user50229
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Why is the (free) neutron lifetime so long?

A neutron outside the nucleus lives for about 15 minutes and decays mainly through weak decays (beta decay). Many other weakly decaying particles decay with lifetimes between $10^{-10}$ and $10^{-12}$ seconds, which is consistent with $\alpha_W…
Forever_a_Newcomer
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What stabilizes neutrons against beta decay in a neutron star?

Free neutrons are known to undergo beta decay with a half-life of slightly above 10 minutes. Binding with other nucleons stabilizes the neutrons in an atomic nucleus, but only if the fraction of protons is high enough (at least a third or so). But…
Slaviks
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Can neutrinos "hit" electrons?

I understand that particles interact via the fundamentals forces of nature. For example photons interact with matter because they carry the change in the electromagnetic field. Neutrinos, on the other hand, do not interact with the electromagnetic…
user
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Why does the weak force distinguish left and right handedness?

I'm wondering why the weak interaction only affects left-handed particles (and right-handed antiparticles). Before someone says "because thats just the way nature is" :-), let me explain what I find needs an explanation: In the limit of massless…
jdm
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Can the weak force create a bound state?

My understanding is that the exchange of Z bosons could yield an attractive or repulsive "force" between two fermions. For most combinations the electromagnetic or strong interactions will take place. However, if we have two neutrinos, or a neutrino…
Brian Bi
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What exactly does the weak force do?

I know that the weak force acts on nuclei and causes decay. But what exactly does the weak force do? Or to put it another way, why do we call it a force? Does it push the red particle of the picture away from the nucleus? Is it called a force only…
PNS
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Are there analogs to resistance, inductance, capacitance, and memristance connecting the weak force to electromagnetism?

A question was asked over at EE.SE recently which I tried to answer, but much of my answer was speculative. I'm hoping someone here can help my ignorance. In electronics design, there are four physical quantities of interest: voltage, flux, charge,…
Stephen Collings
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What gives mass to dark matter particles?

Assuming that dark matter is not made of WIMPs (weakly interacting massive particles), but interacts only gravitationally, what would be the possible mechanism giving mass to dark matter particles? If they don't interact weakly, they couldn't get…
safesphere
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Why must the speed of light be the universal speed limit for all the fundamental forces of nature?

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 must the speed of light be also the universal…
asmaier
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How to explain the weak force to a layman?

I'm trying to explain in simple terms what the weak interaction does, but I'm having trouble since it doesn't resemble other forces he's familiar with and I haven't been able to come up (or find on the web) with a good, simple visualization for it.
Platypus Lover
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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 discrepancy? What is the explanation for this? An…
ODP
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Weak contribution to nuclear binding

Does the weak nuclear force play a role (positive or negative) in nuclear binding? Normally you only see discussions about weak decay and flavour changing physics, but is there a contribution to nuclear binding when a proton and neutron exchange a…
Simon
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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, which plays the role as (for example) the electric…
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