BBN Tensions And The LambdaCDM Model

Stacy McGaugh's latest post at his Triton Station blog explains why Big Bang Nucleosynthesis (BBN) poses a challenge to the LambdaCDM Standard Model of Cosmology. 

Basically, BBN favors a lower primordial baryon density as of the time of nucleosynthesis, while the cosmic microwave background (CMB) astronomy data when interpreted in light of the LambdaCDM model in a model-dependent way, favors a primordial baryon density as of the time of nucleosynthesis that is two times higher.

But, there are lots of technical issues that make the 4-5 sigma discrepancy less obviously an irreconcilable conflict than it might otherwise seem to be.

Inflationary Cosmology

I'm skeptical of all of the theories described in the abstract below, but I lack the expertise to say with confidence that none of them are correct. 

I am skeptical because, in short, I think that a more accurate description of gravity which gives rise to apparent dark matter and dark energy phenomena, and a mirror universe model in which an anti-matter universe very similar to our own flows backwards in time from the Big Bang, is likely to explain the observations that inflationary cosmology seeks to explain without requiring an exceedingly brief moment of cosmological inflation very shortly after the Big Bang. 

There are peer reviewed published articles that make claims along these lines, but I haven't devoted the time necessary to gain a firm grasp of this literature.

We give a brief review of the basic principles of inflationary theory and discuss the present status of the simplest inflationary models that can describe Planck/BICEP/Keck observational data by choice of a single model parameter. In particular, we discuss the Starobinsky model, Higgs inflation, and α-attractors, including the recently developed α-attractor models with SL(2,ℤ) invariant potentials. We also describe inflationary models providing a good fit to the recent ACT data, as well as the polynomial chaotic inflation models with three parameters, which can account for any values of the three main CMB-related inflationary parameters A(s), n(s) and r.

Renata Kallosh, Andrei Linde, "On the Present Status of Inflationary Cosmology" arXiv:2505.13646 (May 19, 2025).

A Claimed Major Advance In QCD Calculations

This paper makes some big claims. Let's see if it will be published and if others agree that it works. The author doesn't appear to currently be an academic physicist, but has 34 physics preprints over many years, mostly on renormalization and running parameters, and some with co-authors.

We introduce Scale Factorized-Quantum Field Theory (SF-QFT), a framework that performs path-integral factorization of ultraviolet (UV) and infrared (IR) momentum modes at a physical scale Q∗ before perturbative expansion. 

This approach yields a UV-finite effective action whose Wilson coefficients Ci(Q) and coupling aeff(Q) are fixed by matching to experiment. Because the two-loop β-function is universal in massless QCD, aeff(Q) evolves with a scheme-independent equation, with higher-order β-coefficients absorbed into the Ci. 

Applying SF-QFT to the inclusive ratio Re+e− gives RSF−QFT(31.6GeV) = 1.04911 ± 0.00084, in excellent agreement with experiment (Rexp(31.6GeV) = 1.0527 ± 0.005) while requiring orders of magnitude fewer calculations than a conventional four-loop MS-bar approach. 

We find universal algebraic recursion relations that generate all higher-order contributions without additional Feynman diagrams, yielding scheme-invariant predictions with remarkable convergence. SF-QFT provides a rigorous proof for the existence of a positive mass gap in Yang-Mills theory, resolving one of the Millennium Prize Problems by demonstrating how non-perturbative effects emerge naturally from the path-integral factorization. 

For QED, the same formalism integrates out high-energy modes above Q∗, producing scheme-independent predictions for the electron anomalous magnetic moment with unprecedented precision (a(theory)(e) = 0.001 159 652 183 56(76)). 

SF-QFT heralds a paradigm shift in quantum field theory, replacing the pursuit of ever-higher loop orders with a unified framework that handles both perturbative and non-perturbative physics while maintaining manifest gauge invariance and eliminating renormalization ambiguities.

Farrukh A. Chishtie, "Scale Factorized-Quantum Field Theory (SF-QFT): An innovative framework for yielding scale and scheme invariant observables" arXiv:2505.09947 (May 15, 2025).

As an aside, per Wikipedia, the value in the new paper of 0.001 159 652 183 56(76) compares to the current state of the art anomalous magnetic moment calculations and measurements as follows:

As of 2016, the coefficients of the QED formula for the anomalous magnetic moment of the electron are known analytically up to  and have been calculated up to order :

$${\displaystyle a_{\text{e}}=0.001159652181643(764)}$$

The QED prediction agrees with the experimentally measured value to more than 10 significant figures, making the magnetic moment of the electron one of the most accurately verified predictions in the history of physics. (See Precision tests of QED for details.)

The current experimental value and uncertainty is:$${\displaystyle a_{\text{e}}=0.00115965218059(13)}$$

So, this new paper exceeds the experimentally measured value by 3.9 sigma, while the state of the art five loop calculation (which is admittedly far more cumbersome to calculate) exceeds the experimentally measured value by 1.4 sigma. Realistically, the uncertainty in the new calculation method is really about two or three times greater than claimed, even though a nine or ten significant figure precision calculation is still pretty impressive.