dukwon

21 ms·

1.
by dukwon 2y ago
They are there in the print version (page 26) https://cerncourier.com/wp-content/uploads/2024/12/CERNCouri...
2.
by dukwon 2y ago
The strong decay would just be forbidden from conservation of energy. If the mass of the Tbb state is less than the sum of the B+ and the B0 masses, then that decay isn't allowed.
3.
by dukwon 3y ago
"at least several weeks" is technically correct but I think a bit of an understatement. A sector takes about 3-4 weeks to warm up and 4-5 weeks to cool down. Then it needs to undergo powering tests and probably some "traini
4.
by dukwon 5y ago
It won't improve our understanding of quantum numbers in general (a quantum number is just a discrete conserved quantity). The final paragraph mentions measuring the quantum numbers of this particular particle, namely its angular momen
5.
by dukwon 5y ago
In the world of double-open-heavy-flavour hadrons (to which this particular tetraquark belongs), you get bullshit headlines like this https://www.sciencealert.com/new-quark-fusion-releases-signi...
6.
by dukwon 5y ago
No. The presence of a valence antiquark guarantees it will decay at some point.
7.
by dukwon 5y ago
A stable heavy-quark tetraquark shouldn't live longer than, say, the B_c meson, which has a lifetime of about 5×10^-13 s
8.
by dukwon 5y ago
> Do they not show up in all collisions This is the biggest factor > why not, wrong matter, wrong speed? Quantum mechanics is probabilistic. The probability of these particular particles in these particular collisions is very small. S
9.
by dukwon 5y ago
Your comment kind of implies that theorists analyse the data. (They don't even have access to it.) Analysis is the job of experimental physicists (like me) and can take years. We don't wait until we have theoretical interpretation
10.
by dukwon 5y ago
I copied the link from an email sent by the guy who maintains the page.
11.
by dukwon 5y ago
If you think of the Hamiltonian as a 2x2 matrix operating on the flavour eigenstate, there are off-diagonal terms arising from the amplitude of spontaneously changing from particle to antiparticle. The leading-order diagrams look like this:
12.
by dukwon 5y ago
That might be how it works in astronomy, but not in particle physics. The collaborations which build and operate the detectors are also the people who get to analyse the data. There is "open data" but it's released after a lo
13.
by dukwon 5y ago
2 of the 10 people who worked on the analysis are at Oxford. The rest are affiliated to CERN, Milano-Bicocca, EPFL and Manchester
14.
by dukwon 5y ago
The time-dependent probability of being in either flavour eigenstate is sinusoidal. It's not like a ticking clock.
15.
by dukwon 5y ago
They're genuinely working on being able to deliver it in the back of a van: https://home.cern/news/news/physics/cern-approves-two-new-ex...
16.
by dukwon 5y ago
Protons and antiprotons must have the same mass under CPT symmetry
17.
by dukwon 5y ago
Δm is directly proportional to the frequency of the oscillation. (In natural units it is exactly the angular frequency: cos(Δm·t) appears in the decay rate) So indeed Δm=0 means no oscillation. You measure it by essentially counting the num
18.
by dukwon 5y ago
> The headline here should be about the first measurement of a mass asymmetry between matter and antimatter. The mass difference is not between particle and antiparticle, but between the mass eigenstates, which are not antiparticles of e
19.
by dukwon 5y ago
The LHCb collaboration's own summary of the result: https://lhcb-public.web.cern.ch/Welcome.html#Deltamc
20.
by dukwon 5y ago
Sure it can, but it has to proceed via the weak interaction, and it's suppressed by the GIM mechanism. For example, D⁰→γγ (c̅u or cu̅ annihilation) is rare and not yet observed, but it's allowed.
21.
by dukwon 5y ago
> a particle has a slightly different mass from its antiparticle This is not the case, and that would violate CPT symmetry. There are two states with different masses (the mass eigenstates) but they are not antiparticles of eachother. Th
22.
by dukwon 5y ago
Mesons have 'annihilation' decay modes, certainly, but they can also decay in other ways.
23.
by dukwon 5y ago
This (very important) paper from 1967 calls them "weak interaction" and "strong interaction": https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.19... Putting the word "nuclear
24.
by dukwon 5y ago
It's unrelated
25.
by dukwon 5y ago
Maybe. There are plenty of attempts to explain g-2 and LFUV in B decays in one go. But really there's no way to know for sure yet.
26.
by dukwon 5y ago
The experiments each reported 4.9 and 5.0σ observations
27.
by dukwon 5y ago
Nope: https://home.cern/news/press-release/cern/cern-experiments-o...
28.
by dukwon 5y ago
I take it by "as usual" you mean "for the first time since the 1970s"? We have precisely one reason so far to adjust the Standard Model (neutrino oscillation) and it's not a resolved matter of how to do that.
29.
by dukwon 5y ago
5 sigma is the standard for calling something an observation. It is not a barrier to publication! That would introduce horrible biases and encourage p-hacking.
30.
CERN approves two new experiments to transport antimatter in the back of a van(home.cern)
2 points by dukwon 5y ago|2 comments

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