The threshold for peer-review journal articles that propose BSM physics is not very high, and they probably make up around half of HEP-phenomenology articles on arXiv and maybe 2/3 to 3/4 of GR articles on arXiv.
Once the premise of the paper is that the SM and GR are wrong in some respect, the wheels come off the bus, and lack of rigor is excused in lots of physics papers.
This said, some of the problems with the paper, recognizing that it is proposing many kinds of new physics are:
1. Many of its predictions for physical constants are falsified relative to their experimental values at more than a five sigma level on their face, and unlike many BSM papers, no real explanation is provided for how this discrepancies could be resolved. The electron charge and the neutrino masses, for example, are all vastly more than five sigma off.
In a more complex quantum theory, you can hand wave and say that your predictions are for the "tree-level" value of fundamental constants and that higher loop calculations are "expected" to make your predictions fit observations. But this paper doesn't even try to claim that.
2. It claims in its abstract to reduce the number of fundamental constants to two but doesn't deliver.
3. There have been numerous observational studies in astrophysics at relatively high redshift to see if the physical constants which they say change actually do change over time. All of those experiments are consistent with a null hypothesis that they don't change.
Certainly, they clearly rule out changes proportionate to the dimensions of the observable post-Big Bang universe, which has at least tripled over the range of observations of the values of the fundamental constants that are supposed to change over time in this theory.
4. It is trying to reconcile Maxwell's equation and GR, not quantum electrodynamics and GR. So, part of the physics it is dealing with is classical and part of it is drawn from the Standard Model. Similarly, apparently the authors have never heard of the Standard Model weak force.
5. Ignoring numerically minor contributions to an equation to simplify it are commonplace in physics, but their equation (2) is very audacious indeed:
It is one thing to neglect the cosmological constant term in Einstein's field equations (which really is negligible in many applications), or to say that the observed phenomena that support the inclusion of the cosmological constant in Einstein's field equations are actually a quantum gravity effect and shouldn't be part of the equation at all. But, ignoring entirely one of the three core remaining terms in Einstein's field equations is over the top given the context in which this is being done. This term is not generically negligible. It is material is a huge range of circumstances. Among other things, it destroys mass-energy conservation in the equations.
6. Another point which a peer review journal with pride really should care about, but apparently didn't, is that the published paper is riddled with capitalization and grammatical errors, as well as numerous more serious copyediting problems in the equations (over and above the substantive flaws in the paper). While these kinds of things aren't a big deal in a first draft of a pre-print written by people who are not native English speakers (three authors are from Thailand and three are from China), the more obvious errors usually get cleaned up prior to publication in a peer-reviewed journal.
7. There is very little review of the literature, which is usually done in a more thorough way in the introduction. Likewise, it refers to all sorts of important theories and findings from others over a whole range of physics and BSM physics with only the most passing of references and no discussion of why it is appropriate to apply them in this situation.
8. More generally, the article bites off far more than can be suitably discussed in a single journal article. Most of its individual chapters are typically the subject of a full journal article. As a result, the discussion of each of these topics is highly superficial.
The gist of the article isn't really any more crazy than lots of other non-crackpot theories, although the fact that half of the authors are from the engineering faculty at a university in Thailand, rather than a physics or astronomy faculty, should raise eyebrows.
So should the fact that it was one of the uncommon papers to solicit another paper criticizing it, published today:
which states:
This is a note of a temporary expression of concern related to potential errors in the formulas of this paper. The concern and this note will remain appended to the above-mentioned article until the investigation is closed and a decision is made regarding the article retraction or correction.
Being placed on a retraction watchlist certainly isn't an auspicious omen for a newly published journal article.
It does not matter if it is experimental or theoretical, it worked also with LK99.
