More Higgs Boson Properties Measured

The experimental data is still strongly consistent with the observed Higgs boson being the Standard Model Higgs boson.

A study of the structure of the coupling between the Higgs boson and the top quark is performed using events from tt¯H and tH production in the H→γγ decay channel, with 164 fb−1 of proton-proton collision data at a center-of-mass energy of s√ = 13.6 TeV collected by the ATLAS detector at the LHC. 

The cross section of the tt¯H process times the Higgs to diphoton decay branching ratio is measured to be 1.46+0.40−0.35=1.46+0.34−0.32(stat.)+0.22−0.13(sys.) fb, corresponding to 1.13+0.33−0.28 times the Standard Model prediction. 

An observed 95% confidence level limit on the tH production cross section times the Higgs to diphoton decay branching ratio is set at 6.2 times the Standard Model prediction, compared to an expected limit of 4.4 times, constituting the most stringent tH upper limit achieved in a single measurement to date. 

The results are combined with 140 fb−1 of proton-proton collision data collected at s√ = 13 TeV in the same production and decay channel, and a CP-mixing angle of |α|>38∘ is excluded at the 95% confidence level, with a purely CP-odd Higgs-top Yukawa coupling excluded at the level of 5.8 standard deviations, providing the most stringent direct constraints on the CP structure of the Higgs-top Yukawa interaction to date.

ATLAS Collaboration, "Probing the Higgs-top Yukawa interaction in the tt¯H and tH processes using H→γγ with the ATLAS detector" arXiv:2606.04855 (June 3, 2026) (Phys. Rev. Lett.) (the paper is 36 pages long including a 20 pages long list of authors).

Dark Matter Phenomena Free Dwarf Galaxies

MOND explains these galaxies with the external field effect. Dark matter particle theories rely upon a tidal stripping hypothesis. More data about these galaxies helps explore and evaluate hypotheses like these. 

Also, to be clear, the distances in the abstract below are from Earth, not from the giant NCG 1052 galaxy (which is the relevant data point for the external field effect and tidal striping hypotheses).

NGC 1052-DF2 and DF4 are two ultra-diffuse galaxies deficient in dark matter (DM), and reported as part of a remarkable linear trail of dwarf galaxies in the NGC 1052 field. 

Recently, NGC 1052-DF9 has been identified as the third galaxy missing DM along the trail. This structure may have been formed in a high-velocity head-on collision between two gas-rich dwarfs, known as the "bullet-dwarf" scenario. However, the trail overlaps in projection with a foreground system, the NGC 1035 group at ∼13 Mpc, raising suspicions that the trail is an artifact of this superposition. 

DF2 and DF4 have been found to be at distances of 21.7±1.2 and 20.0±1.6 Mpc, respectively, using the tip of the red giant branch (TRGB) method with deep Hubble Space Telescope (HST) imaging, but the distances to other trail dwarfs remain unknown. 

In this Letter, we use HST imaging to obtain surface brightness fluctuation (SBF) distance estimates for eight candidate trail dwarfs, as well as for the giant galaxies NGC 1052 and NGC 1035. We find that the dwarfs are all at ∼20 Mpc, and are not associated with the foreground NGC 1035 group. However, for DF2, we derive an SBF distance of 17.7±1.4 Mpc, inconsistent with the published HST TGRB distance (21.7±1.2 Mpc). Meanwhile, James Webb Space Telescope (JWST) observations of DF2 offer a second, and potentially more accurate, TRGB distance of 17.6±0.6 Mpc. While this value matches our SBF result, it is clear that uniform JWST imaging of the remaining trail dwarfs is critically needed.

Yimeng Tang, Gagandeep S. Anand, Aaron J. Romanowsky, Pieter G. van Dokkum, Kevin A. Bundy, "New Measurements of Distances to Galaxies in the NGC 1052 Field with the Hubble and James Webb Space Telescopes: Testing the Bullet-Dwarf Origin of the Trail" arXiv:2606.05144 (June 3, 2026) (Accepted for publication in ApJ Letters).

A Novel GUT

There is virtually no chance that this grand unification theory reflects reality, but it is a quite unusual approach that combines a mishmash of ideas. 

We present an SU(12)×SU(2)(L)×U(1)(R) model unifying SU(9) quark color-flavor with SU(3) lepton flavor as a flavorful alternative to conventional theories of unification. We begin in the ultraviolet with a single yukawa shared by the unified up-type quarks and neutrinos, and no further new fermions. We show that gauged quark color-flavor and lepton flavor instantons dynamically generate the bottom and tau yukawas, which implements a massless quark solution to the strong CP problem and sets up a flavored type-I seesaw mechanism. Only two new scalar irreps are needed for the symmetry-breaking steps, which include quark color-flavor deconstruction and then infrared reunification, and the Standard Model gauge group in this theory emerges as

 

 

 

 

 

where Γ∈{1,ℤ(2)} is the electroweak global structure and there is a discrete gauge symmetry X=B−3(L(i)+L(j)−L(k)) which brings additional ℤ(3) global structure to the SM. This gauge symmetry acts as a flavorful upgrade of the ℤ(18)^(B+L) anomaly-free global symmetry of the SM and stabilizes the proton absolutely. Non-invertible chiral symmetry-breaking is crucial to our model, and we discuss the rich spectrum of emergent generalized symmetries and topological defects appearing at various stages. In the infrared, the novel shared quotient between continuous and discrete groups links the one-form and two-form global symmetries of the Standard Model.

Antonio Delgado, Seth Koren, "Quark-Lepton Color-Flavor Unification" arXiv:2605.30413 (May 28, 2026).