Indirect Constraints On Dark Matter-Ordinary Matter Interactions

This very clever analysis strongly constrains the existence of non-gravitational long range interactions between dark matter and ordinary matter. 

Yet, the strong correlation of ordinary matter distributions and inferred dark matter halos, which necessarily follows from, among other things, the radial acceleration relation (RAR), requires such a force. So, this helps to prove that dark matter does not exist and the dark matter phenomena must be a function of modified gravity or a fifth force.

Dark matter's existence is known thanks to its gravitational interaction with Standard Model particles, but it remains unknown whether this is the only force present between them. While many searches for such new interactions with dark matter focus on short-range, contact-like interactions, it is also possible that there exist weak, long-ranged forces between dark matter and the Standard Model. In this work, we present two types of constraints on such new interactions. 

First, we consider constraints arising from the fact that such a force would also induce long range interactions between Standard Model particles themselves, as well as between dark matter particles themselves. Combining the constraints on these individual forces generally sets the strongest constraints available on new Standard Model-dark matter interactions. 

Second, we consider the possibility of constraining new long-ranged interactions between dark matter and the Standard Model using the effects of dynamical friction in ultrafaint dwarf galaxies, especially Segue I. Such new interactions would accelerate the transfer of kinetic energy from stars to their surrounding dark matter, slowly reducing their orbits; the present-day stellar half-light radius of Segue I therefore allows us to exclude new forces which would have reduced stars' orbital radii below this scale by now.

Zachary Bogorad, Peter Graham, Harikrishnan Ramani, "Constraints on Long-Ranged Interactions Between Dark Matter and the Standard Model", arXiv:2410.07324 (October 9, 2024).

The Nobel Prize In Chemistry In 2024

Commentators have noted the AI trend in both the physics and the chemistry awards this year. 

The Nobel Prize in Chemistry was awarded on Wednesday to three scientists for discoveries that show the potential of advanced technology, including artificial intelligence, to predict the shape of proteins, life’s chemical tools, and to invent new ones.

The laureates are: Demis Hassabis and John Jumper of Google DeepMind, who used A.I. to predict the structure of millions of proteins; and David Baker of the University of Washington, who used computer software to invent a new protein.

From the New York Times.