A Possible Glueball Resonance

A glueball is a strong force bound system without any valence quarks that binds gluons, the carrier bosons of the strong force instead of quarks. A well-established resonance seen in experiments at discovery level significance since 2011, whose internal structure is unclear, is shown in a new preprint to be consistent with a nearly pure pseudoscalar glueball state (i.e. a spin-0, electromagnetically neutral boson with odd parity and no valence quarks).

The properties of glueballs (which depend primarily on a single experimentally measured physical constant, the strong force coupling constant), have been calculated from the very early days of quantum chromodynamics (QCD), which is the Standard Model theory of the strong force. And, there are only a modest number of theoretically possible glueballs. This resonance is on the low end of, but consistent with, the mass predicted for a pseudoscalar glueball.

But distinguishing a glueball resonance from a non-glueball resonance is difficult, and because glueballs are always bosons and share quantum numbers with bosons that include valence quarks, they have a natural tendency to blend with similar bosons making a mere glueball component in a resonance rather than a pure glueball, something that is probably common in reality.

There have only been a few resonances that have been convincingly interpreted as a near pure glueball, and this is one of them. But the fact that this is an analysis of a lone author which has not yet been published in a peer reviewed journal bodes caution in accepting this conclusion as definitive. But to the extent that this analysis holds up, it confirms an important qualitative prediction of QCD (i.e. the existence of glueballs with various quantum numbers that have their predicted masses).

In this work, we take the X(2370) with J^PC = 0−+ as a glueball consists of three valence gluons, and construct a six-quark current based on rigorous current-field duality to obtain the glueball-quark Lagrangian. Then we perform Fierz transformation to bosonize the quark current into a series of three pseudoscalar mesons. At last, we obtain ratios among the partial decay widths of the glueball to three pseudoscalar mesons in a model-independent way, which are compatible with the experimental data from the BESIII Collaboration and support assigning the X(2370) as a glueball.

Zhi-Gang Wang, "Analysis of the X(2370) as a glueball based on rigorous current-field duality" arXiv:2608.03362 (August 4, 2026).

In other physics news, the Higgs boson continues to be consistent with Standard Model expectations in newly observed ways.

Sterile Neutrino Parameter Space Further Constrained

Observations of high energy out space sourced neutrinos from an Earth based neutrino detector further constrain the parameter space of possible sterile neutrinos in a way that the LHC, reactor experiments, and an Antarctica based cosmic ray observatory do not.

While the sterile neutrino mass range probed (1-100 TeV) is vastly greater than the active neutrino mass range, this is a sterile neutrino mass range frequently considered in see saw neutrino mass models, so it is relevant for discriminating between hypotheses.

The money chart, below, is a bit difficult to explain, but the key point is that it adds new constraints that rule out sterile neutrinos with certain properties with masses ca. 12-120 TeV, that other experiments can't probe. 

We investigate the sensitivity of the Pierre Auger Observatory to physics beyond the Standard Model arising from magnetic-moment-induced transitions between active and heavy sterile neutrinos. Such dipole portal interactions can enhance neutrino-nucleon cross sections above a kinematic threshold set by the sterile neutrino mass, leading to observable modifications of neutrino detection rates at ultrahigh energies (UHE). 

We estimate the impact of these interactions on both down-going and Earth-skimming neutrino detection channels, the contrasting responses of which enable discrimination between an enhanced neutrino flux and a modified interaction cross section. Using the non-observation of UHE neutrino candidates, we derive neutrino-flux-dependent constraints with 90% confidence-level on the transition magnetic moment for sterile neutrino masses in the range 1 TeV-100 TeV. Under the assumed flux scenarios, the resulting flavor-independent limits extend existing bounds into previously unexplored parameter space.

Pierre Auger Collaboration, "Search for active-sterile neutrino transitions using Pierre Auger Observatory data" arXiv:2608.01496 (August 2, 2026).

A New Higgs Boson Mass Measurement

Every new precision measurement of the Higgs boson mass is golden, and it is increasingly being pinned down to some precision.

A measurement of the Higgs boson mass in the diphoton decay channel is performed using proton-proton collision data at a center-of-mass energy of 13 TeV. The data set recorded with the CMS detector between 2016 and 2018 is used, corresponding to an integrated luminosity of 138 fb−1. A refined detector calibration and new analysis techniques are employed to improve the precision of the results compared to earlier measurements. The Higgs boson mass is measured to be mH = 125.13 ± 0.15 GeV = 125.13 ± 0.10 (stat) ± 0.12 (syst) GeV. 

In addition, a combination with the mass measurement at center-of-mass energies of 7 and 8 TeV in the diphoton final state is performed resulting in mH = 125.06 ± 0.14 GeV = 125.06 ± 0.09 (stat) ± 0.11 (syst) GeV.

CMS Collaboration, "A measurement of the Higgs boson mass in the diphoton decay channel in proton-proton collisions at s√ = 13TeV" arXiv:2607.28396 (July 30, 2026) (Submitted to Physics Letters B.).

This result compares to a Particle Data Group global average of 125.13 ± 0.11 GeV (S = 1.5).

LambdaCMD Still Broken

No matter how much you fuss with the LambdaCDM based simulations, they generically predict the wrong number and type of satellite galaxies (related study here) producing a 2.4 sigma tension:

The kinematic approach yields a larger diversity in central dark matter densities than expected from the CDM population, as inferred from the stellar-to-halo mass relation, with compact ultra-faints appearing overdense and larger systems appearing underdense. For the ultra-faint dwarfs with at least 10 stars with spectroscopic measurements, this discrepancy persists at the ~2.4σ level across all considered systematic variations on the semi-analytic modeling.

The Hubble tension remains unresolved, which implies that the cosmological constant, Lamba, of the LambdaCDM model, isn't actually constant. And at galaxy scales, CDM has lots of problems:

Small-scale cosmic structure provides a powerful test of the fundamental nature of dark matter (DM). A wide range of DM models impact matter clustering on small scales, including warm, fuzzy, and (self-)interacting DM. In these scenarios, DM physics such as free-streaming, wave interference, and self/Standard Model interactions alter the abundance and internal structure of DM halos. Cosmological and astrophysical probes of nonlinear structure---including dwarf galaxies, strong lensing, the Lyman-α forest, stellar streams, and high-redshift galaxies---are therefore sensitive to these effects. 

Here, we review DM constraints provided by small-scale structure, focusing on observables that probe scales smaller than ∼1 Mpc, which define the frontier of current measurements. We summarize how these constraints have been translated to limits on microphysical DM models, and we discuss key modeling uncertainties and observational systematics. Finally, we highlight the growing importance of probe combination and simulation-based inference for this field, and we overview upcoming observational facilities that will sharpen small-scale structure tests of DM physics.

Ethan O. Nadler, Keir K. Rogers, Alex Drlica-Wagner, "Dark Matter Constraints from Small-Scale Cosmic Structure" arXiv:2607.28564 (July 30, 2026) (73 pages, submitted to Reviews of Modern Physics). The conclusion of this article states:

Over the past two decades, measurements of small scale structure have evolved from potential challenges to the CDM paradigm into a powerful probe of the fundamental nature of DM. For example, the combination of increasingly complete observations of faint galaxies and stellar streams, advances in strong lensing, and the development of flexible, empirically-grounded modeling frameworks has enabled robust inference that connects DM microphysics to data at the small-scale frontier. As a result, these probes now provide among the most stringent constraints on many DM properties, complementing LSS analyses and terrestrial experiments. At the same time, our understanding of small-scale cosmology remains incomplete, and new tensions have emerged on highly nonlinear scales, many of which are related to the inner densities of low-mass subhalos. 

Small-scale structure will likely play a central role in an eventual DM discovery. In the presence of a terrestrial detection, cosmological confirmation will be essential to show that newly-detected particles are the cosmological DM, and small-scale structure provides a uniquely sensitive avenue to achieve this goal. Conversely, evidence for departures from collisionless CDM inferred from nonlinear structure would offer critical guidance for direct detection and collider experiments by narrowing the viable particle DM parameter space. Thus, small-scale structure acts as a bridge between astrophysics and particle physics, creating interdisciplinary opportunities at the interface of astrophysical data and particle theory. 

A key milestone in the coming years will be the detection (or robust exclusion) of DM halos with masses below the galaxy formation threshold. Establishing the existence of completely dark halos would open a new observational window into structure formation and enable the most incisive small-scale structure tests of DM physics to date. On the other hand, an absence of such systems would constitute strong evidence against CDM and for DM physics beyond gravity. Either outcome will mark an important transition in our understanding of DM. 

Realizing the potential of upcoming small-scale structure data will require both observational and theoretical advances. On the observational side, next-generation facilities will dramatically increase the statistical power of current probes while enabling the first DM constraints from new data. On the theoretical side, progress will depend on accurately modeling nonlinear structure across DM scenarios, robustly marginalizing over the impact of baryonic physics on small-scale structure, and combining data from multiple probes in a unified framework. Together, these developments point toward a future in which small-scale structure enables precision tests—and perhaps discovery—of fundamental DM physics.

This article, however, is far too tentative and unwilling to drawn any conclusions from an already abundant supply of observations in its exceptionally long review of the literature and prospects for future study.

While the Hubble tension has received more widespread mainstream attention, the galaxy and galaxy cluster scale issues with cold dark matter particles is, IMHO, the far greater challenge to the LambdaCDM model. In measure after measure, it fails irremediably. 

The Linguistic Golden Age

The most notable findings of the study are that the number of languages in the world was already starting to decline five hundred years before the Columbian exchange and the Renaissance, and that small pre-agricultural populations placed an effective limit on the number of languages spoken in the pre-Holocene era. The peak number of languages was on the order of 10,000 to 35,000 according to the study under various model assumptions.

A linguistic “golden age” flourished between 1,000 to 3,000 years ago when tens of thousands of languages were spoken throughout the world, according to a new study coauthored by Yale linguist Claire Bowern that traces trajectories in global language diversity over the past 12,000 years.

The golden age was followed by a period of rapid decline in linguistic diversity that coincided with the rise of large states and multinational empires, such as the Roman Empire, the researchers found. The finding challenges a commonly held view that widespread language extinction began later, about 500 years ago, with the onset of European colonial expansion.

The languages of expanding states and empires were disproportionately likely to survive while those of absorbed, displaced, or declining populations disappeared, the researchers concluded. This means that the roughly 7,600 languages spoken or signed today represent a small and historically biased sample of the languages that once existed, which has important implications for the study of global patterns in language and culture, they said. . . .

The study, which was published July 23 in the journal Science, is the result of a long international collaboration between experts in language, demography, and evolutionary biology. . . .

Direct evidence of languages doesn’t exist before the appearance of writing about 6,000 years ago. So for the study, the researchers combined ethnographic information, estimates of prehistoric population size, and statistical and social-computational modelling to estimate linguistic diversity over the course of the Holocene — the current geological epoch that began about 12,000 years ago.

To gauge the likely distribution and sizes of populations before the advent of agriculture, the researchers used ethnographic data from 171 hunter-gatherer and fisher societies whose traditional subsistence and mobility had not been profoundly transformed by contact with food-producing populations. They combined these estimates with independent analyses suggesting that the global human population 12,000 years ago was between approximately 4.4 and 7 million. Assuming that the number of languages in the early Holocene corresponded with the number of distinct groups that the total human population could accommodate at the time, between 4,500 and 6,200 languages were spoken 12,000 years ago, the study’s models estimated.

The world immediately before agriculture was probably not exceptionally rich in languages,” said lead author Damián Blasi, an ICREA (Catalan Institution for Research and Advanced Studies) research professor based at the Center for Brain & Cognition at the Pompeu Fabra University in Barcelona, Spain. “There were most likely fewer languages than there are today. Linguistic diversity then grew alongside the human population for thousands of years.”

To capture fluctuations in linguistic diversity as populations expanded dramatically following the onset of agriculture and technological innovation and then contracted through wars, plagues, and other ecological factors, the researchers modelled thousands of possible trajectories connecting language estimates at the beginning of the Holocene with the present.

The models consistently produced patterns indicating that language diversity peaked between 1,000 and 3,000 years ago when upwards of tens of thousands of languages were being spoken worldwide, this period that the researchers call the world’s linguistic “golden age.”

That golden age ended with the rise of states and multinational empires as the dominant groups spread their languages, cultures, and pathogens to previously independent populations, the study shows. European colonialism intensified the steep decline in linguistic diversity, but did not cause it, according to the study.

The loss of so much linguistic diversity over the course of two millennia affected the development of today’s languages, the researchers said.

“The languages we see today are the survivors of a massive and highly selective historical bottleneck,” said study coauthor Russell Gray, director of the Department of Linguistic and Cultural Evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “A linguistic feature may be common not because it is inherently efficient or better for communication, but because it happened to be carried by populations that expanded. Extinction may have shaped linguistic diversity much more profoundly than we previously appreciated.”

"Study uncovers lost ‘golden age’ of languages: A new study coauthored by Yale linguist Claire Bowern suggests that tens of thousands of languages were spoken between 1,000 and 3,000 years ago." via a Yale University press release.

Conventional linguistic reconstruction methods struggle to reconstruction linguistic pre-history much before 4,000 to 8,000 years ago.

The 7,600 languages spoken today is rapidly falling (according to Ethnologue, there are approximately 7,159 known languages spoken around the world today). A very large share of all languages spoken today have a small number of speakers or are moribund and on the brink of extinction in the next couple of generations or sooner. 

The general consensus is that between 6,000 and 7,000 languages are currently spoken. Some linguists estimate that between 50% and 90% of them will be severely endangered or dead by the year 2100. The 20 most common languages, each with more than 50 million speakers, are spoken by 50% of the world's population, but most languages are spoken by fewer than 10,000 people. . . . More than 50% of the world's endangered languages are located in just eight countries: India, Brazil, Mexico, Australia, Indonesia, Nigeria, Papua New Guinea and Cameroon.

From Wikipedia. About 107 languages are spoken by 7 million people or more and about 200 languages are spoken by a million people or more. A list of the number of languages per country can be found here. 

Roughly 40% of languages have less than 1,000 speakers (that's a total of 3,193 endangered languages) spoken collectively by much less than 3 million people out of 8.3 billion people in the world. About 10 million people speak a language that is spoken by 10,000 or fewer people. About 46 languages have only a single speaker. The Ainu language of Japan has 10 speakers. The median Australian Aboriginal language has 10 speakers. The median Native American language in the U.S. has 12 speakers. The median Brazilian indigenous language has 210 speakers. The median Papuan language has 1,315 speakers. The median Indonesian language has 3,500 speakers. The median Mexican indigenous language has 4,730 speakers. The median languages spoken in Cameroon has 10,000 speakers. The median language in Nigeria has 14,000 speakers. The median language in India has 35,000 speakers. 

Reviving an extinct or endangered or purely liturgical language is not impossible but is very difficult and there have been only about twenty moderately successful attempts to do so. The most successful effort has been the Hebrew language.

The Model Dependence Of Cosmological Neutrino Mass Estimates

Even with greatly relaxed cosmology based bounds in neutrino mass that free it from the strong model dependence it has in the deeply flawed ΛCDM model, cosmology based limits on neutrino mass have a 90% confidence level upper bound that is about five times more strict than direct measurements of neutrino mass.

The relaxed less model dependent bound on neutrino mass still limits the lightest neutrino mass to about 60 meV in an inverted hierarchy scenario, and to about 73 meV in a normal neutrino mass hierarchy. In the restrictive and model dependent ΛCDM model estimation of the neutrino masses, there is a normal neutrino mass hierarchy and the lightest neutrino mass can't be much more than 2 meV which a best fit value that is much smaller than that.

Very low neutrino masses greatly limits the role that neutrinos can play to make up the gap between modified gravity theories that account for most, but not all, dark matter phenomena, such as MOND.

Neutrino oscillations establish that neutrinos are massive, providing the only laboratory detection of physics beyond the Standard Model. Direct kinematic experiments bound the electron-neutrino mass to m(νe) < 0.45 eV (KATRIN, 90% CL), implying ∑m(ν) ≲ 1.3 eV. 

Conversely, cosmology within ΛCDM is highly constraining: Planck CMB, CMB lensing, and DESI DR2 BAO yield ∑m(ν) < 0.056 eV (95% CL), in 2-3σ tension with the inverted-ordering floor (0.10 eV). However, this bound relies on ΛCDM, while data hint at an evolving dark energy. 

To determine the model dependence of cosmic neutrino mass bounds, we deconstruct each probe's sensitivity to late-time physics and pursue two robust routes to a ∑m(ν) bound: 

(i) The existing dark-energy-marginalized route, retaining all data and marginalizing over (w(0),w(a)), is shown to also be immune to flexible binned and cubic w(a) histories, yielding ∑m(ν) < 0.152 eV, sharpening to σ(∑m(ν)) ≈ 0.043 eV with Simons Observatory lensing and Spec-S5 BAO.

(ii) A new late-Universe-free route combines primary CMB, marginalizing over acoustic-peak smoothing via Alens, with the reconstructed lensing spectrum CκκL, removing late-time expansion dependence by construction. This yields ∑m(ν) < 0.41 eV today, tightening to 0.31 eV (Simons Observatory) and 0.28 eV (cosmic-variance limit) across all tested dark-energy models. These relaxed bounds trade statistical power for model independence. Interestingly, they land in the sensitivity range targeted by next-generation laboratory experiments like Project 8 (m(νe) ∼ 0.1 eV), motivating vital synergies between future cosmological and terrestrial neutrino measurements.

Frank J. Qu, et al., "Measuring Cosmic Neutrino Masses Independently of Dark Energy" arXiv:2607.24742 (July 27, 2026).

The Pre-Greek Substrate

A nice Facebook reel discusses the pre-Greek substrate of the Indo-European Greek language for which we have about 1000 Greek words that don't appear to have Indo-European origins as evidence.

The geographic extent of the pre-Greek substrate

It notes the geographic extent of the substrate (which is similar to that of modern Greece plus the west coast of Turkey), and the subject matter of the substrate words including animals, plants, toponyms, terrain types, large sea related words, other natural phenomena, proper names, and particularly notably, most of the gods in the Greek pantheon. It also notes distinctively non-Indo-European phonemes found in many pre-Greek substrate words like "nth" and "ss" which were suffixes in the pre-Greek substrate.

My intuition is the the pre-Greek substrate had a larger than average impact on Greek compared to other Indo-European languages, but probably less than the Indo-Anatolian languages. The fact that many god names were borrowed into Greek also suggests that this may be a general feature also shared by Indo-Aryan (i.e. Sanskrit derived) and Indo-Iranian language, and perhaps by Germanic languages as well.

Some substrate source words:

Davidski At Eurogenes On The Indo-European Homeland

Davidski at Eurogenese has provided some thoughts on the Indo-European homeland in a teaser post with an updated large data set of ancient and modern DNA from Europe. He states:

(Interactive version here)

- Yamnaya is almost certainly derived from Serednii Stih (aka Sredny Stog). I've been talking about this for years and you can probably pick it up without too much trouble in the PCA above. Finally, even Iosif Lazaridis, David Reich, Nick Patterson and friends are now on board with this idea as per their latest paper on the topic (see Lazaridis et al. 2025).

- However, I'm not convinced by the Lazaridis et al. hypothesis that the Caucasus–lower Volga (CLV) cline is intimately linked to the Indo-Anatolian and proto-Anatolian expansions. That's because the CLV cline is an artifact of isolation-by-distance working for thousands of years across a vast and highly diverse landscape, and it includes a wide range of populations that usually have nothing to do with each other.

- The question of who actually spoke Indo-Anatolian first will, in all likelihood, never be solved to everyone's satisfaction. But the number of true candidate groups is actually quite small, and I reckon they're almost certainly all highlighted in my PCA above. Wink, wink, nudge, nudge.

My longstanding hypothesis is that Indo-Europeans established themselves in Anatolia close in time to the first historical attestation of their presence in the 18th century BCE, and that the Indo-Anatolian languages are more divergent than other Indo-European languages due to a stronger substrate effect from the Hattic language and related pre-Indo-European languages from Anatolia, because the substrate culture that they conquered was a vital and functioning Copper Age culture rather than the nearly collapsed Neolithic cultures that other Indo-Europeans encountered as a substrate. I believe that conventional wisdom in the field of historical linguistics attributes too much of the divergence between the Anatolian languages and other Indo-European language to the time depth from their common ancestor dialect.

New Combined Standard Model Constant Measurements

A new study tries to extract several Standard Model Constant measurements from the same data set and obtains results generally consistent with prior efforts to measure the same constants, but with greater uncertainty than the state of the art measurements of these quantities.

X17 Hypothesis Less Constrained Following Reanalysis of Data

The conclusion of a new reanalysis of X17 relevant experimental data loosens the constraints greatly. But, I remain deeply skeptical of its existence.

Also, why use units of 10^-3 GeV instead of MeV in your key chart?

[T]he revised exclusion limits no longer extend to the X17 mass of 16.88 MeV, leaving a sizeable region of parameter space for the vector-boson interpretation of the anomaly, bounded by the NA64 and Orsay constraints. Interestingly, the remaining allowed interval, 6.5 × 10^−5 ≲ εe ≲ 1.1 × 10^−4, is compatible with the recent preliminary measurement of the X17 lifetime. We further observe that, for these coupling values, the X17 decay length for a 100 GeV/c e− beam-dump experiment is of the order of few meters, resulting to an invisible signature for a missing-energy setup such as NA64-e [51]. The X17 parameters space not any longer constrained by E141 could thus be explored in the near future by NA64 through the invisible-mode dataset accumulated so far by the experiment.

Since its first observation by the ATOMKI experiment in 2018, the ∗Be anomaly has attracted considerable interest within the dark sector community as it may indicate the existence of a new fundamental particle with a mass of about 16.9 MeV, the X17. However, the minimal model describing X17 as a new vector boson is severely constrained by null results from legacy beam-dump experiments. Among these, the E141 experiment at SLAC places stringent limits on the X17 coupling to electrons εe in the 5.1 × 10^−5 ≲ εe ≲ 1.7 × 10^−4 region. 

This excludes the possibility of a long-lived X17, potentially in contrast with the preliminary estimate of the particle lifetime recently reported by the ATOMKI collaboration. The E141 limits commonly adopted in the literature rely on reinterpretations of the original analysis under solid but simplifying assumptions. While these studies provide a reliable estimate of the experiment's reach, they rely on approximations that were well justified when the boson mass was largely unconstrained. With the X17 mass now confined to a narrow region by recent experimental observations, a more refined treatment of the E141 sensitivity becomes necessary. 

In this work, we revisit the E141 exclusion limits in the X17 scenario by performing a dedicated reanalysis that incorporates a more accurate treatment of the experimental setup and signal prediction. We quantify the impact of these refinements on the excluded parameter space and discuss their implications for the compatibility between the E141 constraints and the vector boson interpretation of the ATOMKI anomalies.

A. Celentano, A. Marini, L. Marsicano, "Updated E141 constraints on a long-lived X17 vector boson" arXiv:2607.22102 (July 24, 2026).

Another recent X17 paper highlighted by @neo is as follows:

The X17 particle has been proposed to explain the invariant mass anomalies observed in electron-positron pairs during nuclear transitions at the Atomki experiment. Motivated by recent observations of 8B solar neutrinos induced coherent elastic neutrino-nucleus scattering (CEνNS), we present the first comprehensive analysis of the hypothetical boson using data from multi-ton dark matter direct detection facilities. 

We consider the new particle as a light Z′ mediator arising from a spontaneously broken U(1)′ symmetry, featuring both vector and axial-vector couplings to leptons. By evaluating the latest datasets from XENONnT, PandaX-4T, and LUX-ZEPLIN, we derive stringent limits on the effective vector coupling utilizing marginalization procedures. Our global analysis provides competitive constraints that meaningfully narrow the allowed parameter space of the model, while exhibiting a clear sensitivity to the tau-flavor coupling.

M. F. Mustamin, M. Demirci, M. Deniz, "Signatures of X17 through Coherent Elastic Solar Neutrino-Nucleus Scattering in Direct Detection Searches"arXiv:2607.12691 (July 14, 2026).

The conclusion of this article states:

Motivated by the first observation of coherent elastic neutrino-nucleus scattering induced by 8B solar neutrinos, we have derived robust constraints on the effective couplings of a light Z′ gauge boson, interpreted here as the X17 particle. Initially conjectured to explain the invariant mass anomalies observed by the Atomki experiment, this hypothetical mediator can be handled within a U(1)′ gauge symmetry framework. Crucially, we have explicitly accounted for the flavor-dependent nature of the couplings, which naturally arise from solar neutrino flavor transitions during their propagation to Earth. 

Our analysis utilized the latest datasets from direct detection searches at XENONnT, PandaX-4T, and LUX-ZEPLIN experiments. While these multi-ton direct detection facilities were fundamentally designed to search for weakly interacting massive dark matter particles, their recent milestone in detecting solar neutrino-induced nuclear recoils offers a novel and powerful avenue for probing BSM physics. We systematically evaluated the flavor-dependent effective couplings—Cνe eff, Cνµ eff, and Cντ eff—that quantify the X17 interactions with the xenon target. By rigorously marginalizing over the relevant effective neutrino couplings, we have derived comprehensive 1 dof and 2 dof limits of the effective vector couplings using each dataset released by the experiments. Our global analysis reveals that PandaX-4T and LUXZEPLIN provide relatively similar behavior, while the combined datasets effectively break individual experimental degeneracies. Most importantly, we have found that the SM hypothesis remains completely protected and consistent within the 90% CL allowed regions across all flavor combinations. Overall, our derived bounds are highly competitive with the allowed parameter spaces previously mapped by IceCube and COHERENT+reactor studies. We also highlight the sensitivity of these detectors to the tau-flavor coupling, a direct consequence of the oscillated solar neutrino flux.

A non-lepton universal coupling seems particularly dubious.

The Pipeline

I scan about 45,000 physics articles a year. I bookmark and think carefully about around 4,500 of them a year. I read the underlying article's body text for about 450 of them a year. I blog about 150 of them a year.

This is post 3,001 at this blog.

Another Gravitational Alternative To Dark Matter

Entropic gravity models, which imply that gravity is an emergent law of physics, rather than a fundamental force in its own right, are a very attractive possibility from a reductionist perspective. This paper looks at an entropic gravity theory that would eliminate the need for dark matter and suggests a way to observationally distinguish it from ΛCDM and MOND models. It doesn't work out the cosmological implications of the theory, however, although since it replicates MOND in other contexts, it can be expected to be similar to it in the area of cosmology.

While modified entropy models-such as Barrow, Tsallis, Kaniadakis, Power-law, Logarithmic, and Rényi entropies-have been widely explored in cosmological contexts, their implications on galactic scales remain largely untested. These generalizations of the Bekenstein-Hawking entropy encode quantum gravitational, nonextensive, or fractal spacetime effects and can alter the gravitational entropy-area relation. 

In this paper, we demonstrate that the entropic force framework, when applied to galactic rotation curves and the baryonic mass of galaxy clusters, uniquely selects Tsallis entropy as the specific generalized entropy formulation. We then extend this Tsallis modified gravity to globular clusters to complete the structural hierarchy from galaxies to galaxy clusters to globular clusters and to investigate its behavior as a function of system scale. 

We will show that the nonextensive parameter exhibits no correlation with any of the macroscopic quantities characterizing gravitational systems, such as mass, radius, temperature, or density. Furthermore, it has previously been shown that entropy is not well-defined within the standard thermodynamic approach to gravity. The adoption of nonextensive statistics provides a foundation for entanglement, thereby enabling a consistent definition of entanglement entropy. 

We predict the existence of galaxy clusters with δ=1 (i.e., clusters whose dynamics require no dark matter) analogous to δ=1 systems already observed at galactic and globular cluster scales. This prediction provides a unique observational test to discriminate Tsallis gravity from ΛCDM and MOND. Therefore, for the entropic gravity paradigm to be consistent with observational data across all scales-from globular clusters to galaxies to galaxy clusters-it is inevitably required to be built upon Tsallis entropy.

S. Shamari, A. Sheykhi, "Resolving Galactic and Cluster Dynamics Without Dark Matter: Tsallis Entropy as the Unique Foundation of Emergent Gravity" arXiv:2607.19435 (July 21, 2026).

The introduction to this paper in the body text provides context for the entropic gravity concept, which is follows by subsequent sections that lay out the equations implied by the theory and by its competing explanations of dark matter phenomena in detail:

The quest to understand the fundamental nature of gravity, space, and time has led to profound theoretical innovations, among which the thermodynamic-gravity conjecture stands as a pivotal insight. Originally formulated by Jacobson and later enriched by Padmanabhan’s emergence paradigm, this conjecture posits that gravitational field equations-including those of General Relativity-can be derived from thermodynamic principles applied to spacetime horizons. In this framework, the Bekenstein-Hawking entropy S = A/(4G) plays a central role, linking the geometry of horizons to the statistical mechanics of spacetime microstates. In recent years, however, various quantum-gravitational, nonextensive, and fractal-spacetime considerations have motivated generalizations of this entropy formula, giving rise to modified entropy prescriptions such as those of Barrow, Tsallis, Kaniadakis, Power-law, Logarithmic and Rényi. These extended entropies introduce new parameters that encode departures from standard thermodynamics and may reflect deep-seated quantum or geometric properties of spacetime. 

To date, research on modified entropies has been predominantly cosmology-centric. Studies have explored how such corrections alter the Friedmann equations, influence dark energy models, modify inflationary scenarios, and leave imprints on the cosmic microwave background. 

While these investigations have placed valuable constraints on entropy parameters using large-scale cosmological data, a critical and largely uncharted frontier remains: how do modified entropies manifest on galactic and sub-cosmological scales? 

Galaxies-and the dark matter halos that host them-represent gravitational systems with well-defined effective horizons and rich dynamical observables (rotation curves, velocity dispersion profiles, baryonic mass-velocity relations). Yet, the implications of horizon thermodynamics for such systems have scarcely been explored, leaving open the question of whether galactic kinematics can serve as a new, independent test bed for quantum-gravitational entropy corrections. 

Our aim here is to bridge this gap by developing and applying a framework to test modified entropies through galactic-scale observations. We posit that if horizon thermodynamics underpins gravitational dynamics, then the entropy associated with the boundary of a galaxy or a dark matter halo-be it the Hubble radius of a galaxy group or the radius enclosing a fixed density contrast should govern its equilibrium properties. Using the entropic force scenario proposed by Verlinde [1] we derive modified force laws and mass-velocity relations that depend explicitly on the chosen entropy form. These relations can then be confronted with high-precision galactic data from surveys such as SPARC (for rotation curves), MaNGA (for stellar kinematics), and other spatially resolved kinematic datasets. 

Although the origins of the dark matter problem trace back to the early 1930s with the work of Zwicky and Oort, it only became a hot research topic when Vera Rubin published her observations of galactic rotation curves. Today, after nearly a century of diverse astrophysical observations from the dynamics of galaxy clusters to gravitational lensing studies and baryon acoustic oscillations a consistent picture emerges: approximately 85% of the matter in the universe is non-baryonic. Despite extensive searches, direct detection of dark matter particles remains elusive, motivating serious consideration of alternative ideas [2–7]. 

Many different theories have been proposed to explain this puzzle without non-baryonic dark matter such as Modified Gravity (MOG), Modified Newtonian Dynamics (MOND), Carmelian theory, Cooperstock model, etc [8–12]. 

Deur does not get a mention, although his approach deserves it. References [8-12] are:

[8] J. W. Moffat, Scalar-Tensor-Vector Gravity Theory, J. Cosmol. Astropart. Phys. 2006, 004 (2006). 

[9] M. Milgrom, A Modification of the Newtonian Dynamics as a Possible Alternative to the Hidden Mass Hypothesis, Astrophys. J. 270, 365 (1983). 

[10] F. I. Cooperstock and S. Tieu, Galactic dynamics via general relativity: A compilation and new developments, Int. J. Mod. Phys. A 22, 2293 (2007). 

[11] M. Carmeli, Is Galaxy Dark Matter a Property of Spacetime?, Int. J. Theor. Phys. 37, 2621 (1998). 

[12] S. Behar and M. Carmeli, Derivation of the Tully-Fisher Law from General Relativity Theory: Doubts about the Existence of Halo Dark Matter, Int. J. Theor. Phys. 39, 1397 (2000). 

A parallel line of inquiry emerged from black hole thermodynamics, following the discovery that black holes possess entropy proportional to their horizon area and temperature. Jacobson demonstrated that the Einstein field equations are nothing but an equation of state for spacetime. Verlinde’s entropic gravity framework realizes the idea that gravity itself may be an emergent phenomenon, with spacetime possessing intrinsic thermodynamic properties. In this thermodynamic paradigm, the choice of entropy functional becomes crucial. While Bekenstein-Hawking entropy leads to standard general relativity, any alternative entropy yields modified gravitational dynamics [13–16]. 

In this work, we classify all possible entropy modifications into two types of generalized entropies. We first examine their performance in reproducing galactic rotation curves; in this assessment, only Tsallis entropy succeeds. Next, we investigate their performance in galaxy clusters. We reconstruct a well-known model and again evaluate each modified entropy. Once more, Tsallis entropy emerges successful. We then extend this Tsallis modified gravity to globular clusters to complete the structural hierarchy. After analyzing and plotting the corresponding figures, we turn to the origin of Tsallis entropy and its theoretical implications. 

This paper is structured as follows. Section II critically examines type-II entropies, demonstrating their failure at galactic and cluster scales. In Section III, we derive the Tsallis-modified force law and apply it to galaxy clusters, presenting our observational analysis of 40 clusters. We then extend this framework to globular clusters, analyzing the velocity dispersion profiles of 33 such systems. In Section IV, we discuss the theoretical foundations of nonextensive statistics in gravitational systems, drawing on the work of Chavanis and others, and interpret the physical meaning of the Tsallis parameter δ in terms of dynamical relaxation and hidden constraints. Section V presents our central prediction: the existence of dynamically relaxed galaxy clusters that are observationally dark matter-free, offering a decisive test to distinguish Tsallis gravity from ΛCDM and MOND. Finally, Section VI is devoted to closing remarks. Throughout this paper we set ℏ = c =kB =1.

Another notable new paper on galactic dynamics, which has phenomenological merit, but is probably flaws in its mechanism is:

We investigate whether the observed fine structure and asymmetry of non-averaged galactic rotation curves can be reconstructed directly from the observed HI distribution within the framework of a kinetic gas transport description. Using the observed HI density profiles separately for the approaching (north-eastern) side and the receding (south-western) side of the galaxy NGC~3198, we reconstruct the corresponding rotation curves based on the equation previously derived in Lipovka 2022. It is shown that the reconstructed curves reproduce not only the approximately flat large-scale behaviour of the observed rotation curves, but also their detailed local morphology and asymmetry separately for the north-eastern and south-western sides of the galactic disk. The obtained results indicate that the local structure of galactic rotation curves is closely connected with the local HI distribution and arises naturally as a consequence of kinetic gas transport processes in galactic disks.

Anton A. Lipovka, Anna A. Lipovka "Local morphology and asymmetry of galactic rotation curves in a kinetic gas transport framework: NGC 3198" arXiv:2607.19505 (July 21, 2026).

The abstract of Lipovka 2022 is as follows:

In this paper, I show that generally accepted methods of classical mechanics are not applicable for calculating the outer parts of the rotation curves of galaxies, where an influence of collisions on gas dynamics becomes dominant. In addition, the hydrodynamic approach cannot be used for this purpose due to an extreme rarefaction of the gas. I develop a new approach to describing the gas dynamics in outer regions of galactic disks, where the gas dynamics is determined mainly by collisions. 

Equations (free from restrictions imposed on hydrodynamics) are obtained that describe the dynamics of rarefied gas. The resulting equations relate two quantities: the tangential velocity of the gas as a function of the distance from the center of a galaxy (rotation curve) and the radial distribution of the gas density. It is shown that if the physical properties of the rarefied gas are properly taken into account, then dark matter is not required, and the "nonphysical" (non-Keplerian) rotation curves of the outer parts of the galactic disks are tailwinds that can be described within the framework of conventional gas kinetics. 

To illustrate the correctness of the obtained model, two galaxies with flat rotation curves (NGC7331 and NGC3198) are considered. From the observed rotation curves, using Eq. (14), the radial densities of the gas are calculated. An excellent agreement was obtained between the calculated gas densities and their observed values, which is a serious argument in favor of the developed model. Thus, the non-physical rotation curves of spiral galaxies represent the tailwinds of gas, the dynamics of which is naturally described by the kinetic equation without involving the concept of dark matter. The total masses of two galaxies NGC7331 and NGC3198 have been calculated. The implications for cosmology are discussed.

This theory purports to explain MOND dynamics without either particle dark matter or modified gravity, using interstellar, apparently basically baryonic, gas dynamics. Any theory that works without significant new physics deserves serious attention, but I'm skeptical that it really describes the mechanism of dark matter phenomena. 

Strong Field General Relativity Fits The Data

All strong gravitational field observations are indistinguishable from general relativity. 

The troublesome cases are in weak gravitational fields in very large systems like galaxies that are usually modeled with simple Newtonian gravity because the math necessary to calculate their behavior in full GR is too hard and is assumed by good arguments, but without actual calculations that could capture non-perturbative effects, to be insignificant.

The signals from the LIGO-Virgo-KAGRA network of gravitational-wave (GW) detectors allow us to perform sensitive tests of general relativity (GR) in the dynamical and strong-field regime of gravity. 

We present the results of seven tests of GR using the observed binary signals in the fifth GW Transient Catalog (GWTC-5.0), i.e., up to and including the second part of the fourth observing run (O4b). We restrict our analysis to the confident signals, henceforth called events, observed by at least two detectors that have estimated false alarm rates ≤ 10^−3 yr^−1. These include 72 events from O4b and five events from the first part of the fourth observing run that are now analyzed due to their increased significance from updated search results, bringing the total number of events for tests of GR in the cumulative GWTC to 168. 

After subtracting the best-fit waveforms, we find the residuals are consistent with detector noise for all events considered. We also find no strong evidence for additional polarizations beyond those predicted by GR. 

We perform tests of GW generation, improving the constraints on deviations from the GR post-Newtonian coefficients by factors of 1.2-2.6. 

Finally, we find overall consistency of the remnants with GR using both time- and frequency-domain methods. For GW240621_195059, postmerger data are consistent with the dominant quadrupolar (ℓ = |m| = 2) mode of a Kerr black hole and its first overtone, with spurious high-frequency content preventing a spectroscopic constraint of GR. In the frequency-domain ringdown analysis, the GR prediction lies in the tails of the combined results, possibly due to the limited catalog size. 

However, the combined results indicate improved consistency with GR over GWTC-4.0, owing to the contribution of GW250114 with a network matched-filter signal-to-noise ratio of 76.9. Overall, we find no evidence for physics beyond GR.

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, "GWTC-5.0: Tests of General Relativity" arXiv:2607.19293 (report number LIGO-P2500781) (July 21, 2026).

Neutrinos Are Very Likely Very Light

Adopting the cosmological bounds on the sum of the neutrino masses and making some other unambitious assumptions, this paper argues that the lightest of the three neutrino masses is less than 2.3 meV and considers a possible phenomenological relations between the three neutrino masses. Direct measurements of the electron neutrino mass at the Katrin experiment bound it at less than 450 meV with good prospects of reducing the bound to 200 meV, but that is still at least two orders of magnitude less than the likely true value.

By way of comparison, the mass of an electron is about 511,000,000 meV, and the first generation quarks are in the low single digit billions of meVs. 

Determining the absolute neutrino mass scale remains one of the most compelling challenges in particle physics. To constrain theoretical models, establishing precise relations among neutrino masses is essential. We propose a simple integral representation of the neutrino mass-squared differences Δm(ij)^2 that provides a complementary perspective on these oscillation parameters. We then demonstrate its utility through several examples. 

Specifically, assuming stringent cosmological bounds that confine the sum of neutrino masses near the normal ordering floor, we derive an analytical condition for the lightest neutrino mass, m(1) < √(61Δm(21)^2)/30. Using recent data from the JUNO experiment, this yields a competitive upper limit of m(1) < 0.0023 eV (95% C.L.). 

We also formulate practical analytical bounds for m(2) and m(3) adaptable to future data, and translate the results into allowed ranges for the effective electron and Majorana neutrino masses m(νe) and m (ββ). Finally, we show that neutrino mass relations of the Gatto-Sartori-Tonin type emerge directly from the proposed integral representation.

I. Alikhanov, "Integral representation of the neutrino mass-squared differences" arXiv:2607.19340 (July 21, 2026).

As a footnote, the body text has a very readable and useful introduction section that addresses many of the main outstanding elements of neutrino physics.

Medieval DNA From Russia

Medieval ancient DNA from Eastern Europe is consistent with the historical and linguistic narrative of the peoples who make up the Russian state.

The foundation of the first ancient Rus’ state occurred as a result of the consolidation of diverse communities inhabiting Eastern Europe during the second half of the first millennium CE. Historical sources imply that these communities mostly include East Slavs, whose settlement across a vast territory led to the emergence of the East Slavic/Rus’ culture within the Rus’ state. 

We generated genomic data for 200 medieval individuals from different locations to elucidate the origin and genetic structure of the Rus’ population during the early stages of the state formation. Our findings reveal a genetic continuum predominantly shaped by two key genetic groups: a broad Slavic-related continuity of different genetic subclusters of Rus’ occupying the enormous European Plain area, and a Fenno-Ugrian (Uralic)-related component in the Northern Rus’ region. Importantly, both groups have a shared genetic substrate inherited from preceding ancient Baltic region populations. 

To scale Scandinavian ("Viking") heritage, we traced minor Scandinavian genetic lineages that did not make up the dominating genetic stratum of the early Rus’ state. 

Our study presents the first comprehensive genomic image of the medieval Rus’, highlighting the intricate cultural and genetic interactions between Slavic, Fenno-Ugrian, and other groups that formed the first Rus’ state affecting Europe’s history.

Andreeva et al., Genetic history of Rus’, bioRxiv (December 30, 2025), doi: https://doi.org/10.64898/2025.12.30.695215 (Hat tip to Davidski at Eurogenes).

The Widest Galaxy

The galaxy with the greatest diameter ever observed (IC1101) has a diameter of 520 kiloparsecs (1.7 million light years), and it is still growing. By comparison, our Milky Way galaxy has a diameter of about 100,000 light years (about 31 kiloparsecs).

More On Wide Binaries

A paper claims to see MOND in a reanalysis of wide-binary star data. I'm still on the fence.

Wide binary stars provide natural laboratories for directly probing gravity in the low-acceleration regime, as dark matter inferred from any viable gravity has negligible effects on their internal dynamics. Various recent studies including Bayesian 3D analyses have shown that wide binaries with separations greater than several thousand astronomical units experience MOND-type gravity with a boost factor of γ≈1.3−1.6. However, results claiming preference for, or no deviation from, standard gravity have also been published during the same period, particularly highlighting the roles of data quality control and realistic modeling of multiple-star (i.e., triple and higher-order) systems that host hidden companion stars. 

Here we carefully reexamine the issues of data quality control and modeling multiple-star systems in statistical gravity tests based on sky-projected 2D velocities of wide binary stars. Through extensive tests including the acceleration-plane test, the ṽ -distribution test, and the median-ṽ -profile test (where ṽ is the sky-plane 2D relative velocity normalized by the Newtonian circular velocity between the two stars), we show that proper data quality control or reasonable variation in multiple-star modeling cannot remove the low-acceleration gravitational anomaly but confirms the MOND-type gravitational anomaly, particularly consistent with recent realistic MOND solutions of wide binary orbits. 

We find that studies claiming no evidence for the low-acceleration gravitational anomaly are consequences of bypassed calibration of the fraction of multiple-star systems using the Newtonian-regime data, bias-introduction in data quality control that is not taken into account in gravity tests, or insufficient statistics in the low-acceleration regime.

Kyu-Hyun Chae, Youngsub Yoon, "Revisiting Data Quality Control and Multiple-star Modeling in Wide Binary Gravity Tests: Confirmation of MOND-type Gravitational Anomaly at Low Acceleration" arXiv:2607.14450 (July 16, 2026) (submitted to the AAS journals).

The Latest Global Electroweak Fits Of Standard Model Physical Constants

A global electroweak fit combines experimentally measured values of Standard Model physical constants with the theoretical relationships between those constants in the electroweak sector of the Standard Model to determine where, within the range of uncertainties in the experimental measurements the true value of those physical constants is most likely to be. Basically, it uses theory to eke out a bit more precision in our determination of these constants than the measurements make possible in isolation.

The fact that it is possible with experimentally measured value of Standard Model physical constants without serious tensions (which it is) also provides a global test of the consistency of the Standard Model with reality.

The latest paper using up to date experimental data to make a global electroweak fit of Standard Model physical constants can be found here. The discussion of how the input values are chosen (basically, an educated best summary of the data to date) in the paper is also noteworthy.

The global fit of the Z boson mass is 91.1882 ± 0.0019 GeV and the global fit of the Z boson width is 2.4945 ± 0.0006 GeV.

The global fit of the W boson mass is 80.3584 ± 0.0048 GeV and the global fit of the W boson width is 2.090 ± 0.001 GeV.

The Higgs boson mass is 125.13 ± 0.11 GeV. The Standard Model expectation for the Higgs boson width is 4.10 ± 0.06 MeV; a complete global electroweak fit of the data produces 3.78 + 0.30 − 0.27 MeV, which is consistent with the Standard Model expectation. The couplings of the Higgs boson in an electroweak global fit are within roughly 1% ± 1% of the Standard Model expectation. 

The global fit of the charm quark pole mass (in the MS scheme) is 1.273 ± 0.003 GeV.

The global fit of the bottom quark pole mass (in the MS scheme) is 4.183 ± 0.004 GeV.

The global fit of the top quark pole mass is 172.67 ± 0.56 GeV.

The global fit of the strong force coupling constant at the Z boson squared energy scale is 0.1179 ± 0.0009.

The global fit of the effective leptonic weak mixing angle is sin^2(theta) = 0.23149 ± 0.00005.

Can We Measure The External Field Effect On Earth?

Color me skeptical. 

The External Field Effect can be understood as basically a swamping of a second order MOND effect by first order Newtonian effects, so I'm very doubtful that it could be measured experimentally in the solar system anywhere near Earth. Also, a 0.1 fm precision measurement, i.e. a fraction of the size of a proton or neutron, starts to run into definitional issues about what the object your measuring even is due to quantum mechanics and the parton makeup of hadrons. And, the uncertainty regarding the functional form of a MOND interpolating function further muddies the waters and makes any measurement model dependent.

Despite compelling evidence, the absence of a confirmed dark matter particle has sustained interest in modified gravity as an alternative explanation for the observed phenomenology. One prominent example is Modified Newtonian Dynamics (MOND), which predicts that the internal dynamics of a system depends on the external gravitational field in which it is embedded. This so-called External Field Effect violates the strong equivalence principle (SEP) and is absent in canonical mechanics, making it a promising avenue for experimental tests of modified gravity. 

Motivated by this, we investigate the dynamics of two spherical masses arranged such that their symmetry axis is either parallel or orthogonal to the local gravitational field. We derive solutions describing the internal dynamics of such systems in both strong uniform and radial external fields. In particular, for a radial external field, if the non-relativistic gravitational field is free to have non-vanishing curl, we find that the mutual attraction of the masses in the perpendicular configuration is not strictly aligned with their symmetry axis. It acquires a small transverse component, even when the external gravitational field is everywhere balanced by non-gravitational forces. 

Using these solutions, we determine the spatial and temporal sensitivities required to distinguish the two configurations and systematically assess experimentally relevant effects, including air drag, object size, and surface interactions. As an example, detecting the prediction of the simple MOND interpolating function requires a spatial sensitivity of order 0.1 fm for sub-millimeter masses evolving over approximately 30 minutes. Such times may be achievable with levitated particles or in space-based environments. Experiments operating at lower resolutions are also interesting as independent tests of SEP and place constraints on modified-gravity theories.

Ankit Kumar, et al., "Probing the Strong Equivalence Principle through the External Field Effect. How Do Two Masses Fall?" arXiv:2607.10247 (July 11, 2026).

A Central Black Hole's Rotation Direction Doesn't Determine A Galaxy's Rotation Direction

While I didn't have strong expectations one way or the other, this paper's conclusion is potentially important to understanding galaxy formation, and tends to disfavor a purely accretion hypothesis. 

In contrast, the fairly strong correlation between central black hole size and galaxy size tends to argue for a very important role of central black holes in the galaxy formation process, because black holes only make up ca. 1% of a galaxy's mass.

The paper also makes notable observations about other aspects of spiral galaxy geometry.

We compare the apparent directions of rotation in the plane of the sky of active galactic nuclei (AGNs) and their host galaxies. The direction of rotation of the galaxy was inferred from the direction of the spiral arms, while the direction of rotation of the AGN was inferred from spectropolarimetry, where the change in relative polarization position angle (PA) across broad lines is believed to be caused by equatorial scattering. The numbers of co-rotating and counter-rotating AGNs are equal. 

Studies of the relative position angles of radio jets have implied that there is a "zone of avoidance" where jets avoid being in the plane of disk galaxies. We point out that bi-conical narrow-line-region outflows also avoid the plane of the host galaxy. 

The equal numbers of co-rotating and counter-rotating AGNs exclude the hypothesis that the "zone of avoidance" is due to a lack of large tilts of the black hole rotating axis relative to the host galaxy rotation axis. Our results imply that the relative orientations of spin axes are random, at least for the black hole mass range we consider. 

We propose that changes in the broad-line polarization PA with wavelength that do not closely follow the predictions of the simple equatorial scattering model are a consequence of the scattering dust being clumpy. We note a couple of cases of possible changes in PA over several years, which, if real, could be due to motions of the dust clumps or changing anisotropy of the continuum emission.

Loren Gigi, C. Martin Gaskell, "The direction of rotation of supermassive black holes is unrelated to the direction of rotation of the host galaxy" arXiv:2607.06902 (July 8, 2026).