Cosmic particles called neutrinos may offer insight into why the universe didn't instantly vanish following the immense explosion known as the Big Bang.
The Deep Underground Neutrino Experiment (DUNE), a future international flagship experiment based at Fermilab, aims to shed light on one of the most intriguing questions in cosmology: the matter-antimatter asymmetry in the Universe. If selected, the LArTPC technology could help DUNE reach its goals faster and enhance our understanding at low energies.
DUNE's primary objective is to investigate neutrino oscillations, a phenomenon that reveals neutrinos have mass and switch flavors during propagation. This finding is significant because it implies physics beyond the Standard Model and offers a framework to explain the matter-antimatter asymmetry through leptogenesis.
In the early Universe, particles of antimatter and matter were created in equal amounts. However, the Universe is overwhelmingly made of matter, and neutrinos could help answer the matter-antimatter asymmetry problem. Neutrino oscillations provide experimental proof of this mass and could help explain why there is more matter than antimatter in the Universe, resolving a fundamental cosmological mystery.
The study of neutrino oscillation patterns helps understand how an initial asymmetry in the lepton sector was generated in the early universe and then converted into the baryon asymmetry (matter over antimatter) we observe today. This requires CP violation, baryon number violation, and departure from thermal equilibrium, known as the Sakharov conditions.
Neutrino oscillations motivate extensions of the Standard Model that include heavy right-handed neutrinos or seesaw mechanisms, enabling leptogenesis: the generation of a lepton asymmetry from right-handed neutrino decays that subsequently converts to baryon asymmetry via sphaleron processes. The CP violation in neutrino oscillations can provide the necessary source of asymmetry, and many models connect the observed neutrino mass and mixing parameters to predictions about baryon asymmetry, linking oscillation data to early universe conditions.
Detailed studies using Boltzmann equations show how the decay and inverse decay of heavy right-handed neutrinos, influenced by neutrino oscillation parameters, set the lepton asymmetry that translates into the baryon asymmetry plateau observed today.
Dr Elena Gramellini, a Lederman Fellow at Fermilab, is working on DUNE, developing a Liquid Argon Time Projection Chamber (LArTPC) with a powerful light-collection system. Medium-scale prototypes are being developed to record real neutrino interactions, allowing the technology to be put to the test in a real physics environment. The potential of DUNE will be unlocked in seeing neutrinos from the Sun and supernovae, as well as efficiently recognizing proton decay events.
The LArTPC development is a collaborative effort, with work currently on proof-of-principle designs to ensure the viability of new sensors and characterize their performance. Neutrinos are particles with a tiny, non-zero mass, and studying their oscillation patterns can help understand how neutrinos contribute to the matter-antimatter asymmetry.
In summary, neutrino oscillations are crucial because they prove neutrinos have mass and participate in CP-violating processes that can generate a lepton asymmetry (leptogenesis). This asymmetry then explains why there is more matter than antimatter in the Universe, resolving a fundamental cosmological mystery.
- The study of neutrino oscillation patterns, such as those that could be observed by the Deep Underground Neutrino Experiment (DUNE) using Liquid Argon Time Projection Chamber (LArTPC) technology, is significant for understanding the matter-antimatter asymmetry in the universe, a fundamental question in cosmology.
- In the realm of space-and-astronomy, advanced technology like LArTPC could aid DUNE in correctly interpreting neutrino signals from sources like our Sun and supernovae, which might provide further insights into the Universe's space-time and the role of neutrinos in the matter-antimatter asymmetry.
