Tagged Questions
1
vote
3answers
111 views
Effective operator in four-fermion interaction
In one book, I have got the following lines which I found myself unable to understand what is effective operator? The paragraph is given below:
The weak interaction describes nuclear beta decay, ...
2
votes
2answers
115 views
What is difference between the different 'flavours' of neutrinos?
Moreover, how-come scientist know that muon-neutrino are different from electron-neutrino when they didn't even know what the difference was? Did they interact differently with other particles?
6
votes
1answer
201 views
Weinberg angle measurement methods
I was reading up on the history of $W/Z$ bosons today and I got a little puzzled. I always assumed that people measured $M_Z$ and $M_W$ and then derived the Weinberg angle. But it appears that they ...
2
votes
1answer
401 views
Jarlskog Invariant and its mathematical origin
CP violation is present in the weak interactions if
There are no degeneracies in the up-quark/down-quark matrices
The Jarlskog invariant $J=Im(V_{us} V_{cb} V_{ub}^* V_{cs}^*)$ is nonvanishing
...
0
votes
0answers
95 views
What would the universe be like if Electroweak symmetry were unbroken? [duplicate]
Possible Duplicate:
What happens to matter in a standard model with zero Higgs VEV?
What if the Higgs did not have a "Mexican hat" potential and the therefore it's vacuum expectation value ...
2
votes
1answer
208 views
4th order feynman-diagrams for $e^- + \mu^+ \to \nu_e + \bar{\nu}_\mu$
The task is to draw the two 4th-order Feynman diagrams of:
$$e^- + \mu^+ \to \nu_e + \bar{\nu}_\mu $$
I drew the first one as (time left->right):
...
13
votes
2answers
395 views
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 $10^{-12}$ ...
0
votes
1answer
158 views
Can action of the weak and strong forces be reduced to action of electromagnetic force?
It is known that electromagnetic (EM) fields action on particles is limited to the Lorentz force action. In terms of spinors and currents, the EM field:
(i) rotates the Dirac current around the ...
4
votes
1answer
358 views
CP Violation of the CKM Matrix
Considering the relation between the $SU(2)_{WEAK}$ partners of the $|u \rangle$, $|c \rangle$, and $|t \rangle$ mass eigenstates and the corrseponding downtype eigenstates
$
\left(
...
2
votes
0answers
148 views
Can the mass of longitudinal and transverse W bosons be measured separately?
Some higgsless unified models of particle physics predict that the mass of longitudinally polarized W bosons and the mass of transversely polarized W bosons are different.
In those models, a ...
7
votes
3answers
582 views
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 ...
9
votes
2answers
2k views
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 ...
1
vote
1answer
577 views
Quantum numbers of the helicity states of the W boson
What are the weak hypercharge and weak isospin quantum numbers of the helicity states of the $W^\pm$ and $Z^0$ bosons?
The W boson is a spin-1 massless particle. Consequently it has three helicity ...
2
votes
1answer
213 views
How much CP violation does the weak force cause?
I'm looking for the most readable quantitative explanation, with the least amount of difficult mathematics. Rather than an answer with just a number, I'd like to see the derivation from the CKM ...
6
votes
3answers
2k views
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 ...
1
vote
2answers
250 views
Is there a relationship between Berry-Pancharatnam phase and CP violation in quark mixing?
Berry-Pancharatnam phase is the phase that quantum systems exhibit when they pass through a sequence of states and return to their original state. It's a complex phase and it is different from the ...
3
votes
3answers
468 views
Energy of the electron-muon reaction
Lets see the reaction:
$e^- \mu^- \to e^- \pi^- \nu_\mu \;\;\;\;\;\;\;\;\;\;\; {(1)}$
I suppose, that this reaction occurs as follows
$e^- \mu^- \to e^- \mu^- \pi^+ \pi^- \to e^- \pi^- \nu_\mu$
Is ...
