The hot broth of the early universe seethed with particles and antiparticles. They were born and died in pairs, and by all laws of symmetry should have annihilated each other completely. But something went wrong, and a tiny excess of matter survived. From it, stars, planets, and we ourselves later assembled.
Physicists call this imbalance baryon asymmetry. One explanation is sphalerogenesis: a process where the weak interaction itself sorts particles as the universe cools. You can compare it to a crowd on an escalator: if the steps are slightly higher on one side, people unconsciously drift to one side. So here: special transitions between vacuum states, like the click of a switch, slightly more often produce matter than antimatter.
The authors added new, more subtle interactions to the calculations, so-called dimension-8 operators. Previously, their contribution was thought negligible. But it turns out that if these effects arise from quantum loops, they can rival the main mechanism in strength. It's like discovering that a whisper in a crowd can sometimes drown out a shout.
This approach ties a cosmic mystery to earthly experiments. If new particles or forces really exist, their traces could show up in future collisions at the Large Hadron Collider. The tiny gap in symmetry that opened at the dawn of time may soon become visible in the lab.
as written by the authors arXiv:2608.05950v1
We investigate whether a baryogenesis mechanism known as sphalerogenesis can account for the observed baryon asymmetry of the Universe within the Standard Model effective field theory. In this scenario, the baryon asymmetry is generated through the $$CP$$-asymmetric decoupling of electroweak (EW) sphaleron-like transitions. We introduce seven $$CP$$-violating dimension-8 operators constructed from the Higgs doublet and the $$SU(2)_L$$ gauge fields and show that five of them can individually account for the observed baryon asymmetry with satisfying experimental constraints from colliders or electron electric dipole moment measurements. We further study their impact in the presence of a $$CP$$-violating dimension-6 operator. We find that the dimension-8 contributions can be comparable to the dimension-6 contribution when the dimension-8 operators are generated at one loop, demonstrating that loop-order counting can be as important as canonical mass-dimension counting in sphalerogenesis.
For every billion antimatter particles in the early universe, there was roughly one extra proton, and that was enough to create all the visible world.
In Dan Brown's novel Angels & Demons, antimatter is stolen from CERN as a weapon, but in reality, producing it costs billions of times more than gold, and the total amount ever produced would fit inside a grain of sand.