The Weak Scale from BBN

Abstract

The measured values of the weak scale, $v$, and the first generation masses, $m_{u,d,e}$, are simultaneously explained in the multiverse, with all these parameters scanning independently. At the same time, several remarkable coincidences are understood. Small variations in these parameters away from their measured values lead to the instability of hydrogen, the instability of heavy nuclei, and either a hydrogen or a helium dominated universe from Big Bang Nucleosynthesis. In the 4d parameter space of $(m_u,m_d,m_e,v)$, catastrophic boundaries are reached by separately increasing each parameter above its measured value by a factor of $(1.4,1.3,2.5,\sim 5)$, respectively. The fine-tuning problem of the weak scale in the Standard Model is solved: as $v$ is increased beyond the observed value, it is impossible to maintain a significant cosmological hydrogen abundance for any values of $m_{u,d,e}$ that yield both hydrogen and heavy nuclei stability. For very large values of $v$ a new regime is entered where weak interactions freeze out before the QCD phase transition. The helium abundance becomes independent of $v$ and is determined by the cosmic baryon and lepton asymmetries. To maintain our explanation of $v$ from the anthropic cost of helium dominance then requires universes with such large $v$ to be rare in the multiverse. Implications of this are explored, including the possibility that new physics below 10 TeV cuts off the fine-tuning in $v$.

26 pages plus appendix, 13 figures

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• Cosmological Simulations with TreeSPH
• Hierarchies without Symmetries from Extra Dimensions
• The QCD phase transition with physical-mass, chiral quarks
• Dimensionless constants, cosmology and other dark matters
• The anthropic principle and the mass scale of the Standard Model
• Likely Values of the Cosmological Constant
• AlterBBN: A program for calculating the BBN abundances of the elements in alternative cosmologies
• Precision Calculation of n+p->d+gamma Cross Section for Big-Bang Nucleosynthesis
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• Quark mass variation constraints from Big Bang nucleosynthesis
• Multiverse Understanding of Cosmological Coincidences
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• Big Bang Nucleosynthesis: The Strong Nuclear Force meets the Weak Anthropic Principle

Cited by in corpus (35)

• Redefining the Axion Window
• Implications of Higgs Discovery for the Strong CP Problem and Unification
• The Degree of Fine-Tuning in our Universe -- and Others
• An Axion-induced SM/MSSM Higgs Landscape and the Weak Gravity Conjecture
• Axi-Higgs Cosmology
• The swampland conjecture and the Higgs expectation value
• Sliding Naturalness: Cosmological Selection of the Weak Scale
• Higgs Parity, Strong CP, and Dark Matter
• Dark Matter, Dark Radiation and Gravitational Waves from Mirror Higgs Parity
• Swampland Constraints on Neutrino Masses
• The Multiverse and Particle Physics
• $\theta$-dependence of light nuclei and nucleosynthesis
• Higgs Parity Grand Unification
• Direct anthropic bound on the weak scale from supernovae explosions
• Naturalness Under Stress
• $\theta$-dependence of the lightest meson resonances in QCD
• Partially Natural Two Higgs Doublet Models
• A landscape for the cosmological constant and the Higgs mass
• Cosmological Selection of Multi-TeV Supersymmetry
• Constraining scalar dark matter with Big Bang nucleosynthesis and atomic spectroscopy
• Radiative PQ Breaking and the Higgs Boson Mass
• The self-tuning of the cosmological constant and the holographic relaxion
• Multiverse Predictions for Habitability: Element Abundances
• Nuclear Processes in Other Universes: Varying the Strength of the Weak Force
• High-scale SUSY from an R-invariant New Inflation in the Landscape
• Anthropics of Aluminum-26 Decay and Biological Homochirality
• Explanation for why the Early Universe was Stable and Dominated by the Standard Model
• Baryogenesis in a Parity Solution to the Strong CP Problem
• Higgs and flavour as doors to new physics
• New Inflation in the Landscape and Typicality of the Observed Cosmic Perturbation
• Quantifying the sensitivity of Big Bang Nucleosynthesis to isospin breaking with input from lattice QCD
• Anthropic Origin of the Neutrino Mass from Cooling Failure
• Window for preferred axion models
• Naturalness as a reasonable scientific principle in fundamental physics
• Weak Scale Triggers in the SMEFT