Dimensionless constants, cosmology, and other dark matters

Tegmark, Max; Aguirre, Anthony; Rees, M. J.; Wilczek, Frank

doi:10.1103/physrevd.73.023505

Cited by 384 publications

(666 citation statements)

References 106 publications

(195 reference statements)

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“…However, environmental selection may provide a possible explanation [54,55]. While the expected abundances in the various components depend on multiverse distribution functions, it is likely that they are very roughly comparable.…”

Section: Multi-component Dark Matter Withmentioning

confidence: 99%

Prospects and blind spots for neutralino dark matter

Cheung

Hall²,

Pinner³

et al. 2013

J. High Energ. Phys.

198

271

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Using a simplified model framework, we assess observational limits and discovery prospects for neutralino dark matter, taken here to be a general admixture of bino, wino, and Higgsino. Experimental constraints can be weakened or even nullified in regions of parameter space near 1) purity limits, where the dark matter is mostly bino, wino, or Higgsino, or 2) blind spots, where the relevant couplings of dark matter to the Z or Higgs bosons vanish identically. We analytically identify all blind spots relevant to spin-independent and spin-dependent scattering and show that they arise for diverse choices of relative signs among M 1 , M 2 , and µ. At present, XENON100 and IceCube still permit large swaths of viable parameter space, including the well-tempered neutralino. On the other hand, upcoming experiments should have sufficient reach to discover dark matter in much of the remaining parameter space. Our results are broadly applicable, and account for a variety of thermal and non-thermal cosmological histories, including scenarios in which neutralinos are just a component of the observed dark matter today. Because this analysis is indifferent to the fine-tuning of electroweak symmetry breaking, our findings also hold for many models of neutralino dark matter in the MSSM, NMSSM, and Split Supersymmetry. We have identified parameter regions at low tan β which sit in a double blind spot for both spin-independent and spin-dependent scattering. Interestingly, these low tan β regions are independently favored in the NMSSM and models of Split Supersymmetry which accommodate a Higgs mass near 125 GeV.1

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Section: Multi-component Dark Matter Withmentioning

confidence: 99%

Prospects and blind spots for neutralino dark matter

Cheung

Hall²,

Pinner³

et al. 2013

J. High Energ. Phys.

198

271

View full text Add to dashboard Cite

show abstract

“…Most calculations of the distribution of Λ in the literature [24,25,26,27,28,29] do not explicitly specify the measure, but in fact correspond to using the pocket-based measure. The distribution of positive Λ in a causal-patch measure has also been considered [30].…”

Section: Introductionmentioning

confidence: 99%

Predicting the cosmological constant with the scale-factor cutoff measure

et al. 2008

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It is well known that anthropic selection from a landscape with a flat prior distribution of cosmological constant Λ gives a reasonable fit to observation. However, a realistic model of the multiverse has a physical volume that diverges with time, and the predicted distribution of Λ depends on how the spacetime volume is regulated. We study a simple model of the multiverse with probabilities regulated by a scale-factor cutoff, and calculate the resulting distribution, considering both positive and negative values of Λ. The results are in good agreement with observation. In particular, the scalefactor cutoff strongly suppresses the probability for values of Λ that are more than about ten times the observed value. We also discuss several qualitative features of the scale-factor cutoff, including aspects of the distributions of the curvature parameter Ω and the primordial density contrast Q.

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“…With cosmological parameters added for quantities such as cosmological constant, dark matter and fluctuation amplitude, the entire world model is specified by about thirty-one numbers. [3,4] Remarkably however, almost all behavior of matter important to everyday life-common nuclear, atomic and molecular physics, chemistry and biology-is shaped by just the gauge couplings and three light fermion masses: those of the electron, and the up and down quarks. [5,6] The behavior of our world depends sensitively on the values of these masses, through the delicately balanced mass differences in the system of electrons, neutrons, protons, deuterons, and heavier nuclei.…”

Section: Introductionmentioning

confidence: 99%

Nuclear astrophysics of worlds in the string landscape

Hogan

2006

Phys. Rev. D

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Motivated by landscape models in string theory, cosmic nuclear evolution is analyzed allowing the Standard Model Higgs expectation value w to take values different from that in our world (w ≡ 1), while holding the Yukawa couplings fixed. Thresholds are estimated, and astrophysical consequences are described, for several sensitive dependences of nuclear behavior on w. The dependence of the neutron-proton mass difference on w is estimated based on recent calculations of strong isospin symmetry breaking, and is used to derive the threshold of neutron-stable worlds, w ≈ 0.6 ± 0.2. The effect of a stable neutron on nuclear evolution in the Big Bang and stars is shown to lead to radical differences from our world, such as a predominance of heavy r-process and s-process nuclei and a lack of normal galaxies, stars and planets. Rough estimates are reviewed of w thresholds for deuteron stability and the pp and pep reactions dominant in many stars. A simple model of nuclear resonances is used to estimate the w dependence of overall carbon and oxygen production during normal stellar nucleosynthesis; carbon production is estimated to change by a fraction ≈ 15(1 − w). Radical changes in astrophysical behavior seem to require changes in w of more than a few percent, even for the most sensitive phenomena.

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Dimensionless constants, cosmology, and other dark matters

Cited by 384 publications

References 106 publications

Prospects and blind spots for neutralino dark matter

Prospects and blind spots for neutralino dark matter

Predicting the cosmological constant with the scale-factor cutoff measure

Nuclear astrophysics of worlds in the string landscape

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