Understanding why matter and antimatter behave differently is key to understanding why there is a universe at all. Now physicists have discovered the latest example of a subtle difference between the stuff that makes up galaxies, stars, planets and us, and its evil-twin opposite.

Particles of antimatter, like anti-electrons and anti-protons, possess the same mass but opposite electric charge as the usual electrons and protons. In a discovery published on Wednesday in the journal Nature, an international collaboration of scientists working at the CERN particle physics laboratory outside Geneva described an imbalance among particles that are cousins to the protons and neutrons that make up everyday objects.

That makes the new observations “very important for us to further understand bigger questions like the matter-antimatter asymmetries in the universe,” said Xueting Yang, a graduate student at Peking University who led the analysis.

The Big Bang that created the universe should have produced equal amounts of matter and antimatter. When a particle of matter bumps into its antimatter counterpart, the two particles annihilate. Thus, all of the matter should have annihilated all of the antimatter in a cataclysmic burst of radiation, leaving an empty universe for eternity.

And yet, 13.8 billion years later, you — made of matter, not antimatter — are reading this news on a device (or in a newspaper), which is also made of matter. Somehow, in the instant after the Big Bang, for each billion or so pairs of matter and antimatter, an extra particle of matter persisted.

This slight tipping of the laws of physics toward matter is known as charge-parity, or CP, violation.

The new findings are based on experiments performed between 2011 and 2018 at the CERN Large Hadron Collider, which slams protons together in head-on collisions. That is the same particle smasher that in 2012 confirmed the existence of the Higgs boson, which imbues other fundamental particles with mass.

The energy of each proton-to-proton collision is like a miniature Big Bang. As Einstein realized, energy and mass are interchangeable — E=mc² — so the energy transforms into particles, and as in the Big Bang, the collision produces both matter and antimatter.

To measure CP violation, a detector on the collider known as LHCb, or Large Hadron Collider beauty, records particle decays that can illuminate how matter behaves differently from antimatter.

You probably learned in school about protons and neutrons, the main constituents of ordinary matter. They belong to a class of particles known of baryons, and baryons are made of three even smaller fundamental particles known as quarks. Physicists have given quarks whimsical names like up, down, strange and charm. A proton consists of two up quarks and one down quark. A neutron has one up quark and two down quarks.

The new findings by Ms. Yang and her colleagues focus on the beauty-lambda baryon, which is a neutron in which one of the down quarks has been swapped for a heavier quark known as beauty or bottom. The smashup of protons sometimes produced a beauty-lambda baryon, and sometimes the baryon decayed into a proton and three other specific particles from a family called mesons, which consist of two rather than three quarks.

They also sorted out instances in which the particle’s antimatter form, an anti-beauty lambda baryon, decayed into the equivalent antiparticles: an anti-proton and three anti-mesons.

What their analysis showed was that the matter version of this decay was a few percent more likely than the antiparticle version. With 80,000 decays observed, statistical analysis indicated that this discrepancy would have less than a one-in-five million possibility of occurring by chance.

Observing CP violation in baryons is important because the ordinary matter of the universe is made of baryons, said Charles Young, a senior scientist a the SLAC National Accelerator Laboratory in Menlo Park, Calif., who was not involved with the research. “And this is the first measurement of it,” he said.

However, it probably will not solve the “Why is there a universe at all?” conundrum.

That is because the beauty-lambda baryon results are most likely a manifestation of a CP violation phenomenon first observed in mesons in the 1960s. That discovery led to prediction of two additional quarks — the top and bottom quarks — and some adjustments to the Standard Model, the set of equations that describes the behavior of fundamental particles and forces other than gravity.

In the 1990s and 2000s, a CP violation was also measured in a group of bottom-quark-containing mesons. But in all of the meson measurements, the magnitude of the phenomenon was far too minuscule to explain the matter-antimatter disparity, and those results fit within the current understanding of the Standard Model.

At first glance, the latest results also appear to fit within the confines of the Standard Model. The experimental findings, however, will help refine and test the complex calculations of theorists.

“The theoretical prediction for baryon decays is still very rough, so it’s hard to have a very precise comparison between the experimental results and theoretical predictions,” Ms. Yang said. “We might have opportunities in the future to explore some new source of CP violation.”

Zoltan Ligeti, a theoretical physicist at the University of California, Berkeley, who was not involved in the research, said that the range of possibilities for CP violation beyond the Standard Model “is not fully known.”

Understanding the results “will probably require performing many similar measurements in the coming years and decades,” Dr. Ligeti said.

Dr. Young said LHCb probably did not uncover new physics, but it was important to check. “You’ve got to try to follow every lead on CP violation,” he said. “Maybe something fantastic will show up.”

The most promising area of particle physics that might be hiding CP violation is the strange behavior of wispy particles known as neutrinos. A series of ambitious experiments, including a vast underground site within a closed gold mine in South Dakota, could turn up clues.