Dimensionless constants, cosmology and other dark matters

By Max Tegmark, A. Aguirre, Martin J. Rees, Frank Wilczek. 2005

329 citations recorded by the source corpus.

We identify 31 dimensionless physical constants required by particle physics and cosmology, and emphasize that both microphysical constraints and selection effects might help elucidate their origin. Axion cosmology provides an instructive example, in which these two kinds of arguments must both be taken into account, and work well together. If a Peccei-Quinn phase transition occurred before or during inflation, then the axion dark matter density will vary from place to place with a probability distribution. By calculating the net dark matter halo formation rate as a function of all four relevant cosmological parameters and assessing other constraints, we find that this probability distribution, computed at stable solar systems, is arguably peaked near the observed dark matter density. If cosmologically relevant weakly interacting massive particle (WIMP) dark matter is discovered, then one naturally expects comparable densities of WIMPs and axions, making it important to follow up with precision measurements to determine whether WIMPs account for all of the dark matter or merely part of it.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7d2ffa2aed2b69aa93bd3ac4aa7897519899e76c

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Citations in the corpus

Why Does Deep and Cheap Learning Work So Well? (2016, methodology): “Taken together, the constraints on locality, symmetry and polynomial order reduce the number of continuous parameters in the Hamiltonian of the standard model of physics to merely 32 [13].”
Dark light, dark matter, and the misalignment mechanism (2011, background): “[14] it was shown, that for an axion or similar dark matter condensate produced during inflation, assuming other parameters do not vary, the regions of universe with dark matter abundance of order the abundance in our observed universe are the most highly correlated with physical features of our uni”
Axions as dark matter particles (2009, background): “[34]–[36] and references therein) and recent discussions of limits on the ‘anthropic’ axion window can be found in [37, 38].”
History of dark matter (2018, neutral): “Alternatively, it was also pointed out that if inflation occurs after the breaking of the Peccei-Quinn symmetry, then there may also be a viable anthropic scenario in which the axion mass could be much lighter (Linde, 1991; Wilczek, 2004; Tegmark et al., 2006).”
Inflationary Cosmology after Planck 2013 (2014, background): “They may even help us to understand why the amount of dark matter is approximately 5 times greater than the amount of normal matter [148, 149] and why the baryon asymmetry is so small, nb/nγ ∼ 10−10 [151].”
Exploring the Role of Axions and Other WISPs in the Dark Universe (2012, background): “A QCD axion with a GUT scale decay constant, fa ∼ 1016 GeV, on the other hand, would overclose the universe, unless the initial misalignment angle is very small, Θa ∼ 10−3 (“anthropic axion window” [80,81]), or there is a late dilution.”
A model for halo formation with axion mixed dark matter (2013, background): “Such a mix of DM may be natural given certain theoretical priors (Aguirre & Tegmark 2005; Wilczek 2004; Tegmark et al. 2006; Bousso & Hall 2013; Wilczek 2013), or in non-thermal cosmologies expected after moduli stabilisation (e.g. Acharya, Bobkov & Kumar 2010; Acharya, Kane & Kuflik 2010).”
Dark Matter Candidates from Particle Physics and Methods of Detection (2010, background): “This latter possibility has some theoretical attractions, as it implies fa near mGUT ' 10(16) GeV may be allowed and provides an avenue for anthropic selection effects to favor axion densities near the observed value (250; 251).”
Varying Constants, Gravitation and Cosmology (2010, background): “, to [485] and to [243] for a general anthropic investigation of the standard model parameters.”