Single-minus gluon tree amplitudes are nonzero
TL;DR
Imagine tiny particles called gluons are like spinning tops. Their spin can be in one of two directions, which physicists call 'plus' or 'minus'. For decades, the rulebook seemed to say that you could never have a situation where just one gluon was spinning 'minus' and all the others were spinning 'plus' — that outcome was thought to be zero. This paper found a loophole. Under very specific, purely mathematical conditions that don't exist in our physical reality but are useful for calculations, this interaction can happen. The researchers wrote down the exact recipe for it, fixing a small but important detail in our fundamental rulebook for how the universe works.
Single-minus tree-level $n$-gluon scattering amplitudes are reconsidered. Often presumed to vanish, they are shown here to be nonvanishing for certain "half-collinear" configurations existing in Klein space or for complexified momenta. We derive a piecewise-constant closed-form expression for the decay of a single minus-helicity gluon into $n-1$ plus-helicity gluons as a function of their momenta. This formula nontrivially satisfies multiple consistency conditions including Weinberg's soft theorem.
- 1Single-minus tree-level $n$-gluon amplitudes are nonzero for certain configurations.
- 2Derived a closed-form expression for single minus-helicity gluons.
- 3Expression satisfies multiple consistency conditions including Weinberg's theorem.
Sub-part-per-trillion test of the Standard Model with atomic hydrogen
Scientists made an incredibly precise measurement of light emitted by hydrogen atoms that tested one of physics' most fundamental theories - the Standard Model - to an accuracy of 0.7 parts per trillion. This measurement also resolved a long-standing disagreement about the size of protons by confirming the smaller value found in previous experiments with exotic atoms.
Rock art from at least 67,800 years ago in Sulawesi
Imagine finding a spray-painted handprint on a cave wall. Over thousands of years, a thin, glassy layer of minerals, like limescale in a kettle, grew on top of it. Scientists used a high-tech laser to analyze that mineral layer. By measuring the natural radioactive decay of elements within it, they figured out the layer is about 71,600 years old. Since the handprint is underneath that layer, it must be at least that old, with the most conservative estimate being 67,800 years. This makes it one of the oldest pieces of art ever found and proves that the early humans who lived on this Indonesian island, who had to cross the ocean to get there, were creating symbolic art.
An interstellar energetic and non-aqueous pathway to peptide formation
Imagine you have a box of LEGO bricks, which are like the basic molecules of life called amino acids. To build anything, you need to snap them together. Scientists used to think you needed a puddle of liquid water to make the bricks 'click'. This experiment is like discovering you can snap the LEGOs together inside a freezer. The researchers took the simplest amino acid, froze it onto a dust grain like you'd find in space, and zapped it with energy that mimics cosmic radiation. They found that the amino acids linked up to form a two-brick chain, the first step towards building a protein. This means the essential first chains for life could be forming all over space and delivered to new planets by comets and asteroids.
A ‘time capsule’ for cells stores the secret experiences of their past
Imagine your cells have millions of tiny, hollow barrels inside them called vaults, and for decades, nobody knew what they were for. Scientists in this study figured out how to open these barrels and put a specific, rolled-up instruction sheet (that's the mRNA) inside. They also designed a special key that can unlock the barrel and release the instructions at a later time. So, they've essentially created a microscopic time capsule inside a living cell, allowing them to tell a cell what to do and, crucially, *when* to do it.