“B mesons can provide insight into the cosmic mystery of matter versus antimatter”
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Did you know that we have facilities in physics dubbed “beauty factories”? These aren’t related to aesthetic pursuits; instead, they are high-energy physics labs where electrons and their antiparticle counterparts, positrons, collide to produce intriguing particles known as B mesons.
B mesons are unique because they consist of quarks – those essential building blocks of ordinary matter. While most matter is composed of electrons, up quarks, and down quarks, a B meson features a peculiar combination of a beauty antiquark with either an up, down, charm, or strange quark.
Due to their composition, B mesons exist for only a fleeting moment, leading one to question the purpose of these so-called “B factories.” The significance lies in the potential of B mesons to unravel one of the universe’s greatest enigmas: the imbalance of matter and antimatter.
It is a well-established fact that every particle has a corresponding antiparticle; however, the observable universe is predominantly composed of matter. For instance, we can detect electrons aplenty, yet positrons, their antimatter siblings, are a rarity.
Mesons occupy a fascinating space between the prevalent matter and the elusive antimatter. By studying B mesons, scientists hope to gain insights into the asymmetry that predominates between these two entities. Such understanding could illuminate why matter persists in a universe where matter and antimatter typically annihilate each other upon contact. The research in B factories thus aims to explain the observable structure of our universe.
The complexity increases when we consider that mesons have their own antiparticles. Each B antimeson consists of a beauty quark combined with an up, down, charm, or strange antiquark. What’s particularly intriguing about neutral B mesons (those formed with strange or down quarks) is their ability to oscillate between being mesons and antimesons, which effectively makes them non-binary in their nature.
These oscillating neutral B mesons are crucial in bridging our understanding of the matter-antimatter inequality. The standard model of particle physics predicts these oscillations to occur in a balanced manner. Researchers are investigating whether the oscillations lean more towards forming mesons or antimesons in these collisions. Any detected imbalance could provide a vital clue to the matter-antimatter asymmetry.
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B factories may help us understand something we are certain exists, but have never seen in the lab: dark matter
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In 2010, Fermilab DZero collaboration researchers observed a 1 percent variation, though no subsequent study has corroborated these findings. Nevertheless, the implications remain fascinating, particularly since independent research has identified discrepancies.
Additionally, B factories present the possibility of shedding light on the mysterious dark matter, a form of matter inferred predominantly through its gravitational effects on visible matter. Current estimates suggest that about 85 percent of the universe’s matter comprises this invisible substance, yet it remains unexplained within the confines of the standard model.
To formulate a theory about dark matter, we often have to propose new particles that might interact with existing particles in subtle ways. The interactions are facilitated by what are known as mediators, which themselves are elusive. While direct observation of such mediators may be challenging, the decay products from these mediators, like electron-positron pairs, could be detectable. This is where B factories come into play – they are engineered to analyze the outcomes of electron-positron collisions.
One of the most fascinating aspects of this research is its ability to keep scientific inquiry alive long after experiments cease producing data. For instance, the BaBar experiment at the SLAC National Accelerator Laboratory, which concluded in 2008, continues to benefit from data analysis, aiding the next generation of physicists in their studies.
Recently, in 2022, Brian Shuve from Harvey Mudd College, along with an undergraduate team, revisited data from the nearly 20-year-old BaBar project to challenge new theoretical propositions including the idea that axions could serve as mediators between visible matter and dark matter. This concept aligns with my ongoing research on axions in the context of dark matter.
The big question remains: do the researched scenarios provide a truthful representation of our universe’s workings? As scientists delve deeper into the matter-antimatter asymmetry, we may soon find answers.
What I’m Reading
I recently finished reading Gazan physics student Wasim Said’s Witness to the Hellfire of Genocide, a harrowing memoir.
What I’m Watching
After much delay, I’m watching The Wire.
What I’m Working On
I’m revisiting cosmological perturbation theory, a topic that once frustrated me.
Chanda Prescod-Weinstein is an associate professor of physics and astronomy at the University of New Hampshire. She is the author of The Disordered Cosmos and the forthcoming book The Edge of Space-Time: Particles, poetry, and the cosmic dream boogie.
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