Baryon asymmetry

Unsolved problem in physics:

What is the source of imbalance of matter and antimatter? This refers to the small non-zero value of baryons over photons (≈ 5 ⁻¹⁰) in the current Universe

(more unsolved problems in physics)

In physical cosmology, the baryon asymmetry problem, also known as the matter asymmetry problem or the matter–antimatter asymmetry problem,^[1]^[2] is the observed imbalance in baryonic matter (the type of matter experienced in everyday life) and antibaryonic matter in the observable universe. Neither the standard model of particle physics nor the theory of general relativity provides a known explanation for why this should be so, and it is a natural assumption that the universe is neutral with all conserved charges.^[3] The Big Bang should have produced equal amounts of matter and antimatter. Since this does not seem to have been the case, it is likely some physical laws must have acted differently or did not exist for matter and/or antimatter. Several competing hypotheses exist to explain the imbalance of matter and antimatter that resulted in baryogenesis. However, there is as of yet no consensus theory to explain the phenomenon, which has been described as "one of the great mysteries in physics".^[4]

^ "The matter-antimatter asymmetry problem". CERN. Retrieved April 3, 2018.
^ Sather, Eric. "The Mystery of the Matter Asymmetry" (PDF). Vanderbilt University. Archived from the original (PDF) on April 4, 2018. Retrieved April 3, 2018.
^ Sarkar, Utpal (2007). Particle and astroparticle physics. CRC Press. p. 429. ISBN 978-1-58488-931-1.
^ Cite error: The named reference MatterAndAntimatterInTheUniverse was invoked but never defined (see the help page).

[1] "The matter-antimatter asymmetry problem". CERN. Retrieved April 3, 2018.

[2] Sather, Eric. "The Mystery of the Matter Asymmetry" (PDF). Vanderbilt University. Archived from the original (PDF) on April 4, 2018. Retrieved April 3, 2018.

[3] Sarkar, Utpal (2007). Particle and astroparticle physics. CRC Press. p. 429. ISBN 978-1-58488-931-1.

[MatterAndAntimatterInTheUniverse-4] Cite error: The named reference MatterAndAntimatterInTheUniverse was invoked but never defined (see the help page).

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