Unraveling a Cosmic Antimatter Mystery

Matter Antimatter Concept Animation

Antimatter is matter made up of the antiparticles of the corresponding particles found in “ordinary” matter.

Physicists invoke the cosmological collider to demonstrate why matter, not antimatter, dominates the universe.

The universe was filled with equal numbers of matter and “antimatter” – particles that are matter counterparts but have opposite charges — early in its existence, shortly after the Big Bang. The universe then cooled as space expanded. Today’s universe is filled with matter-based galaxies and stars. How did matter come to dominate the universe, and where did antimatter go? Scientists are still perplexed by the cosmic origin of matter.

By invoking the “cosmological collider,” physicists from the University of California, Riverside, and Tsinghua University in China have now opened a new pathway for studying the cosmic origin of matter.

Yanou Cui

Yanou Cui is an associate professor of physics and astronomy at UC Riverside. Credit: I. Pittalwala/UC Riverside.

Not just any collider

High-energy colliders, such as the Large Hadron Collider, have been designed to generate very heavy subatomic elementary particles that might reveal new physics. However, certain new physics, such as those explaining dark matter and the origin of matter, can involve far heavier particles, necessitating much more energy than a human-made collider can deliver. It turns out that the early universe may have acted as a super-collider.

Yanou Cui, an associate professor of physics and astronomy at UCR, explained that cosmic inflation, a period when the universe expanded at an exponentially increasing pace, is commonly thought to have preceded the Big Bang.

“Cosmic inflation provided a highly energetic environment, enabling the production of heavy new particles as well as their interactions,” Cui said. “The inflationary universe behaved just like a cosmological collider, except that the energy was up to 10 billion times larger than any human-made collider.”

According to Cui, when the universe expanded, tiny structures formed by energetic events during inflation were stretched, resulting in areas of varying density in an otherwise homogeneous universe. These microscopic structures then seeded the large-scale structure of our universe, which is seen today as the distribution of galaxies throughout the sky. Cui noted that analyzing the imprint of the cosmological collider in today’s cosmos’ contents, such as galaxies and the cosmic microwave background, may reveal new subatomic particle physics.

Cui and Zhong-Zhi Xianyu, an assistant professor of physics at Tsinghua University, report in the journal Physical Review Letters that by applying the physics of the cosmological collider and using precision data for measuring the structure of our universe from upcoming experiments such as SPHEREx and 21 cm line tomography, the mystery of the cosmic origin of matter may be unraveled.

“The fact that our current-day universe is dominated by matter remains among the most perplexing, longstanding mysteries in modern physics,” Cui said. “A subtle imbalance or asymmetry between matter and antimatter in the early universe is required to achieve today’s matter dominance but cannot be realized within the known framework of fundamental physics.”

Leptogenesis to the rescue

Cui and Xianyu propose testing leptogenesis, a well-known mechanism that explains the origin of the baryon — visible gas and stars — asymmetry in our universe. Had the universe begun with equal amounts of matter and antimatter, they would have annihilated each other into photon radiation, leaving nothing. Since matter far exceeds antimatter today, asymmetry is required to explain the imbalance.

“Leptogenesis is among the most compelling mechanisms generating the matter-antimatter asymmetry,” Cui said. “It involves a new fundamental particle, the right-handed neutrino. It was long thought, however, that testing leptogenesis is next to impossible because the mass of the right-handed neutrino is typically many orders of magnitudes beyond the reach of the highest energy collider ever built, the Large Hadron Collider.”

The new work proposes to test leptogenesis by decoding the detailed statistical properties of the spatial distribution of objects in the cosmic structure observed today, reminiscent of the microscopic physics during cosmic inflation. The cosmological collider effect, the researchers argue, enables the production of the super-heavy right-handed neutrino during the inflationary epoch.

“Specifically, we demonstrate that essential conditions for the asymmetry generation, including the interactions and masses of the right-handed neutrino, which is the key player here, can leave distinctive fingerprints in the statistics of the spatial distribution of galaxies or cosmic microwave background and can be precisely measured,” Cui said. “The astrophysical observations anticipated in the coming years can potentially detect such signals and unravel the cosmic origin of matter.”

“Probing Leptogenesis with the Cosmological Collider” by Yanou Cui and Zhong-Zhi Xianyu, 8 September 2022, Physical Review Letters.
DOI: 10.1103/PhysRevLett.129.111301

The research was funded by the U.S. Department of Energy.

5 Comments on "Unraveling a Cosmic Antimatter Mystery"

  1. Howard Jeffrey Bender, Ph.D. | October 15, 2022 at 7:17 am | Reply

    Leptogenesis could be the reason for the lack of antimatter, but since it requires a particle no one can see and can only be assumed by a variety of statistical analysis, it remains firmly in sci-fi territory. If we’re going there, consider String Theory.

    Surely you didn’t think all of the matter and energy we see now was stuffed in a single Big Bang! As you may know, quantum mechanics proposes a roiling quantum foam energy field everywhere in the universe, and the right kind of energy spikes creates string/anti-string pairs. These pairs immediately annihilate each other, but I suggest a process similar to Hawking radiation that form permanent strings that are the basis of all the matter and energy we have. This is a Big Bang/Big Crunch cycle, over and over, that also describes how inflation started and stopped. Interestingly, this same process can be used to form the galaxies we see. Gravity is far too weak to cause anything to combine rather than flying apart from the enormous force of the Big Bang. Specifics for the physical creation of the universe and the galaxies can be found by searching YouTube for “Creating Universes – A String Theory Way”

    • Charles G. Shaver | October 16, 2022 at 6:34 am | Reply

      This morning I watched your YouTube video, paying particular attention to your ‘similar’ summary. Here is a new rough draft of my brief summary of the universe: about fourteen billion years ago a physical universe evolved into a single omniscient and omnipotent sentient entity which became instantaneously bored with being alone in a cold, dark place with nothing to do. With a single thought (perhaps, “Let there be light!”) the then ‘spent’ entity contracted into a relatively small clump of very dense matter which immediately exploded into a new physical universe. Essentially, in popular terminology, God created evolution with a “Big Bang.” Since, a conflict exists. It’s between attractive matter and expansive sentience. Which will win? It really doesn’t matter because either end-state is inherently unstable. To me, with thinking like yours and the vast majority of professional humanity, if it’s similar elsewhere in the universe mindless matter will probably win this round in about another fourteen billion years. As I see it, too, your/Einstein’s problem lies with mistaking pulsing coiled, spiraling and outwardly radiating lines of gravity force for ‘vibrating strings.’ And, at the atomic level there ‘is’ enough ‘gravity’ to hold electrons in orbitals around a nucleus, at well defined distances. A couple of what I perceive to be universal rules: “Artificial experiments tend to produce artificial results” and “moderation is key to the best possible life.”

  2. The interactions and balances of topological vortex fields cover all short-distance and long-distance contributions, and are the basis of the formation and evolution of cosmic matter.In the formation and evolution of cosmic matter, matter and antimatter are mainly shown between the topological vortex and its identical twin anti-vortex, not between the high-dimensional space-time matters formed by their interaction. The material hierarchy and its interaction ways are vital for understanding matter and antimatter.

  3. Matter and antimatter were married in the big bang ceremony. Their divorce became finalized with gravity. Heat and pressure were the groom’s and bridesmaids’ God prevailed as the priest and the universe became the church. We are the atoms of reality, never beginning and never ending.
    Nuff said, peace out…….

  4. … neutrinos!!! Where are those funky anti-neutrinos?

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