Scientists from the KATRIN experiment have achieved the most precise upper limit ever recorded for the mass of the mysterious neutrino – clocking in at less than 0.45 electron volts.
This breakthrough not only tightens the constraints on one of the universe’s most elusive particles but also challenges and extends the boundaries of the Standard Model of physics.
Breaking New Ground in Neutrino Mass Measurement
Researchers with the KATRIN (Karlsruhe Tritium Neutrino) experiment have reported the most precise upper limit yet on the mass of the neutrino: less than 0.45 electron volts (eV). That’s less than one-millionth the mass of an electron. This breakthrough further narrows the possible mass range for one of the universe’s most elusive particles and pushes the boundaries of physics beyond the current Standard Model.
Neutrinos are electrically neutral, extremely lightweight elementary particles – and the most abundant particles in the universe. They come in three types, or “flavors”: electron neutrinos, muon neutrinos, and tau neutrinos. These types can change into one another as neutrinos travel, a phenomenon known as oscillation. This behavior implies that neutrinos must have mass, contradicting the original assumption in the Standard Model that they are massless. Yet their exact mass remains one of the biggest open questions in particle physics.
Ghost Particles
Neutrinos have earned the nickname “ghost particles” because they are incredibly hard to detect–billions of them pass through your body every second without leaving a trace. These tiny, electrically neutral particles interact so weakly with matter that they can pass straight through planets, stars, and even entire galaxies. First predicted in the 1930s and confirmed decades later, neutrinos have since become central to some of the biggest mysteries in physics.
Beta Decay as a Window into Neutrino Mass
In this latest study, Max Aker and the KATRIN Collaboration present findings from the first five data-collection runs of the experiment. KATRIN estimates the neutrino’s mass by studying beta decay in tritium, a radioactive form of hydrogen. In this process, a neutron inside the tritium atom decays into a proton, releasing an electron and an electron antineutrino (the antimatter counterpart of the neutrino). By precisely measuring how the decay energy is split between the emitted electron and the antineutrino, scientists can infer the neutrino’s mass.
Between 2019 and 2021, the KATRIN team recorded the energy of about 36 million electrons – six times more data than in earlier runs. Their analysis led to the most stringent lab-based limit yet on the effective mass of the electron neutrino, placing it below 0.45 eV with 90% confidence. This marks the third major refinement of the mass limit and doubles the precision of previous results.
Toward the Future of Neutrino Science
“The neutrino mass measuring campaign of the KATRIN experiment will end in 2025 after reaching 1000 days of data acquisition,” writes Loredana Gastaldo in a related Perspective. “Analysis of the full data set gained from this grand project will allow for estimating the effective electron neutrino mass close to the projected value of 0.3 eV at 90% confidence level.”
Reference: “Direct neutrino-mass measurement based on 259 days of KATRIN data” by KATRIN Collaboration, Max Aker, Dominic Batzler, Armen Beglarian, Jan Behrens, Justus Beisenkötter, Matteo Biassoni, Benedikt Bieringer, Yanina Biondi, Fabian Block, Steffen Bobien, Matthias Böttcher, Beate Bornschein, Lutz Bornschein, Tom S. Caldwell, Marco Carminati, Auttakit Chatrabhuti, Suren Chilingaryan, Byron A. Daniel, Karol Debowski, Martin Descher, Deseada Díaz Barrero, Peter J. Doe, Otokar Dragoun, Guido Drexlin, Frank Edzards, Klaus Eitel, Enrico Ellinger, Ralph Engel, Sanshiro Enomoto, Arne Felden, Caroline Fengler, Carlo Fiorini, Joseph A. Formaggio, Christian Forstner, Florian M. Fränkle, Kevin Gauda, Andrew S. Gavin, Woosik Gil, Ferenc Glück, Steffen Grohmann, Robin Grössle, Rainer Gumbsheimer, Nathanael Gutknecht, Volker Hannen, Leonard Hasselmann, Norman Haußmann, Klaus Helbing, Hanna Henke, Svenja Heyns, Stephanie Hickford, Roman Hiller, David Hillesheimer, Dominic Hinz, Thomas Höhn, Anton Huber, Alexander Jansen, Christian Karl, Jonas Kellerer, Khanchai Khosonthongkee, Matthias Kleifges, Manuel Klein, Joshua Kohpeiß, Christoph Köhler, Leonard Köllenberger, Andreas Kopmann, Neven Kovač, Alojz Kovalík, Holger Krause, Luisa La Cascio, Thierry Lasserre, Joscha Lauer, Thanh-Long Le, Ondřej Lebeda, Bjoern Lehnert, Gen Li, Alexey Lokhov, Moritz Machatschek, Martin Mark, Alexander Marsteller, Eric L. Martin, Christin Melzer, Susanne Mertens, Shailaja Mohanty, Jalal Mostafa, Klaus Müller, Andrea Nava, Holger Neumann, Simon Niemes, Anthony Onillon, Diana S. Parno, Maura Pavan, Udomsilp Pinsook, Alan W. P. Poon, Jose Manuel Lopez Poyato, Stefano Pozzi, Florian Priester, Jan Ráliš, Shivani Ramachandran, R. G. Hamish Robertson, Caroline Rodenbeck, Marco Röllig, Carsten Röttele, Milos Ryšavý, Rudolf Sack, Alejandro Saenz, Richard Salomon, Peter Schäfer, Magnus Schlösser, Klaus Schlösser, Lisa Schlüter, Sonja Schneidewind, Ulrich Schnurr, Michael Schrank, Jannis Schürmann, Ann-Kathrin Schütz, Alessandro Schwemmer, Adrian Schwenck, Michal Šefčík, Daniel Siegmann, Frank Simon, Felix Spanier, Daniela Spreng, Warintorn Sreethawong, Markus Steidl, Jaroslav Štorek, Xaver Stribl, Michael Sturm, Narumon Suwonjandee, Nicholas Tan Jerome, Helmut H. Telle, Larisa A. Thorne, Thomas Thümmler, Simon Tirolf, Nikita Titov, Igor Tkachev, Korbinian Urban, Kathrin Valerius, Drahoslav Vénos, Christian Weinheimer, Stefan Welte, Jürgen Wendel, Christoph Wiesinger, John F. Wilkerson, Joachim Wolf, Sascha Wüstling, Johanna Wydra, Weiran Xu, Sergey Zadorozhny and Genrich Zeller, 10 April 2025, Science.
DOI: 10.1126/science.adq9592
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2 Comments
Pinning Down a Ghost Particle: Neutrino Mass Measured with Unprecedented Precision.
VERY GOOD.
Ask the researchers:
1. How is quality formed?
2. Are you measuring quality?
3. How do you understand the uncertainty principle?
Every person with normal thinking cannot understand the current peer review in physics, which insists that two sets of cobalt-60 rotating in reverse are two objects that are mirror images of each other.
Every person with normal thinking cannot understand the current physics trend of using a cat to understand quantum.
Let us continue to witness the dirtiest and ugliest era in the history of science and physics with facts.
Question ? can the oscillation of the three types of neutrinos be the mysterious cloak that makes changes to the neutrino as it passes through any matter or field energy , as each neutrino comes in contact with a electron it oscillates to change hiding its subatomic makeup and changes each time as it passes through to the adjoining matter or field .