Neutrinos in matter?
Physicists can collaborate, but sometimes they break up. Hiskazu Minakata’s last paper results from a three year discussion with his collaborator
Hizakasu Minakata, Ph.D., head of the physics department at Yachay Tech, released a new publication, soon to be published on JHEP (Journal of High Energy Physics). With this research endeavor, Professor Minakata seeks to adapt the two flavor model for neutrino persistence in vacuum, to neutrino persistence in matter. But what exactly has this paper meant for him? In the acknowledgements in this new publication, the author gives a clue about how his work has evolved and his journey alongside his previous collaborator Stephen J. Parke.
As scientists say, neutrinos come in three flavors, or “types” if I may. One neutrino flavor actually equals the combination of three different states. As they travel through space, neutrinos change state constantly, and move at different speeds, so to speak, a flavor is the result of different combination of this states and speeds. So, as neutrinos move, this states change constantly, making a neutrino switch flavor too, this is called Neutrino Oscillations. However, when we see them within a particular time and space, we only catch one flavor.
Therefore, physicists expected the neutrino oscillation phenomena, by which neutrino mass was discovered, to show a three flavor nature. But, Stephen Parke and his collaborators discovered in 2005 that the neutrino oscillation probability in vacuum can be written in an effective “two flavor” form in a good approximation. This feature made extraction of flavor mixing parameters from experiments much easier, in particular, in reactor neutrino measurement. Because of the success Stephen wanted to go beyond and asked a question: “Can the similar effective two flavor form be possible in matter?” It was the starting point of his work with Hisakazu Minakata.
Here is where they drifted apart in opinions: In Professor Minakata’s calculus, the genuine three-flavor nature of neutrino oscillation prevails, and the effective two-flavor strategy fails in matter. On the contrary, Stephen believes that Hisakazu’s formalism is too tight. They needed longer than 3 years to confirm that difference in their opinions cannot be tolerated. Thus, the result was published as the single-authored paper by Hisakazu.
Telling the history of Neutrinos, could mean telling the history of the universe. They are as mysterious as dark matter or dark energy, and that is the point. When conducting neutrino research, we could be conducting research about every universe “how” we don’t know the answer for. But this story is more than that, it is a way of proving that science is also a place of misunderstanding and opinion. According to Hisakazu Minakata, he and Stephen Parke parted as friends. You are welcome to bet on who is right reading the paper here.
María Caridad Bermeo and Hizakasu Minakata