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7

When e.g. a neutron decays, there is no "real" W-boson inside, in the sense that it could be detected at every point. Instead, the decay of the neutron involves a "virtual" W-boson, a W-boson that only exists for a very short time. Quantum mechanics allows the energy conservation law to be violated by $\Delta E$ for a very short time $\Delta t$ as long as $\...


5

To add to the other answer: Your intuition is right in a way. The fact that the $W$ and $Z$ bosons are so heavy is the reason for the weakness of the interaction. For example, $\pi^+$ mesons can decay over the weak interaction, the process is described by the following Feynman diagram: According to the Feynman rules, the probability amplitude of such a ...


4

It is not a postulate that the Hilbert space for QFT is a Fock space. In fact, for interacting theories is often almost surely not a Fock space. The requirements for a Hilbert space to be the space of a QFT is that the Wightman axioms are satisfied. For free theories, a suitable Fock representation of the canonical commutation relations satisfies the ...


3

The closest thing to an answer would be, that if a neutron in a nucleus decays into a proton and an electron (beta radiation), the ligher electron is the one that can escape the nucleus. The proton is heavier, and also strongly bound by the strong nuclear force, so it stays there. The same goes for neutrons - they aren't emitted in simple nuclear decays, ...


2

The strong nuclear decay process emits alpha particles that are just helium-4 nuclei. The weak nuclear decay process emits beta radiation that is an electron (usually) with the internal to the nucleus the process $n~\rightarrow$ $p~+~e~+~\nu_e$, or in some cases if energetically possible $p~\rightarrow$ $n~+~e^+~+~\bar\nu_e$. The electromagnetic process is a ...


2

A heavy Higgs is easier to detect because it can decay in ways that lead to an easy detection, e.g. in two W or Z bosons. The background processes that lead to the same signature as what you would get if you have a Higgs decaying into two W's are very low, so you don't need to produce all that many Higgs particles to detect it. But at lower masses, there are ...


2

The CKM matrix describes oscillations but that doesn't mean that it doesn't matter in any other process. The CKM matrix matters pretty much in every process involving quarks. In particular, $d\bar c$ primarily contains two mass eigenstates of quarks. And they are eigenstates from different families. $d$ is the first generation of quarks, $\bar c$ is the ...


2

There is not, because the combined transformation $CPT$ is a symmetry of all Lorentz-invariant systems. The $P$-violating decay distribution observed by Wu et al. is also a $C$-violating distribution, because polarized anti-cobalt would have had the opposite sign of asymmetry. (However no one has ever made, or probably will ever make, polarized anti-cobalt,...


1

No, a weak decay doesn't imply a change of $S$. For example, the decay of the neutron – the basic part of the beta-decay – has $S=0$ both in the initial and final state. So the first proposition is false and only the second one is true.


1

A point particle is an idealization of a particle. It simplifies calculations by using a 0 dimensional object instead of a normal particle in calculations where size, shape, and structure are irrelevant. For example, in the theory of, say, electromagnetism, scientists will talk about a point charge - a particle represented by a point that has a non-zero ...


1

If I have an object A, will a second object exists that is an exact copy of A and cannot be distinguished from the original? If A is a very simple object such as an electron, a nucleon, or even an atom or a small molecule, yes. It is actually an important notion in quantum mechanics that indistinguishable objects (fermions, bosons) collectively behave ...


1

You are correct that quantum mechanics is the basic framework of nature, but not everything in this basic level is quantized, in the sense of coming in a discrete spectrum. Even the spectrum of the hydrogen atom at very high n has such close spacing where it can be called a continuum. The first quantum level is bound atoms. The second level is bound ...



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