9 votes

Hubble expansion rate and reaction rates

A more intuitive way to understand the comparison between the reaction rate $\Gamma$ and the Hubble rate $H$ is to take the reciprocal. $\Gamma^{-1}$ is the time between reactions. $H^{-1}$ is ...
Sten's user avatar
  • 4,644
5 votes

If w bosons can create dark matter neutrinos by decay, can they also create dark energy?

The W boson has a lifetime of $3\times 10^{−25}$ seconds. So any big bang W bosons will have long decayed. So they are not a dark energy source. Also, they produce "hot" relativistic decay ...
Anders Sandberg's user avatar
4 votes

Hubble expansion rate and reaction rates

For a spatially flat Universe (described by FLRW metric), which is consistent with current observation, the scale factor itself is not so relevant. One can always redefine/scale it so that it is e.g. ...
Chen's user avatar
  • 41
2 votes

When two galaxies with dark matter halos merge do they provide evidence for fermionic or bosonic dark matter?

There is no law of physics that prevents fermions getting arbitrarily close to each other. The Pauli Exclusion Principle says that no two fermions can occupy the same quantum state. Basically, this ...
ProfRob's user avatar
  • 152k
1 vote

Why are WIMP dark matter particles, if Majorana-like, expected to annihilate upon contact? But not neutrinos?

Gluons actually annihilate, so do neutrinos, just more rarely than Neutralinos. Neutrinos, Gluons, WIMPS, Majorana particles are always neutral being a Truly Neutral Particle. These Majorana particles ...
Arjun's user avatar
  • 1,256
1 vote

Directionality of solar flares

I have just found this paper which seems very relevant: https://www.sciencedirect.com/science/article/abs/pii/S1350448799000633?via%3Dihub "Particles arising at some remote location from the sun ...
Slarty's user avatar
  • 349

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