New Physics Opportunities at Neutrino Facilities: BSM Physics at Accelerator, Atmospheric, and Reactor Neutrino Experiments
This white paper summarizes the landscape of new physics opportunities beyond neutrino oscillations at current and future accelerator, atmospheric, and reactor neutrino facilities, with a particular focus on East Asian programs and next-generation sensitivities as presented at the NPN 2024 workshop.
Original paper dedicated to the public domain under CC0 1.0 (http://creativecommons.org/publicdomain/zero/1.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine the Standard Model of particle physics as a massive, intricate puzzle that scientists have been assembling for decades. For a long time, it seemed complete, but then they found a piece that didn't fit: the Higgs boson. Since then, the biggest mystery in physics is that this puzzle only explains about 5% of the universe. The other 95% is made of "dark" stuff (dark matter and dark energy) that we can't see or touch.
This paper is like a roadmap for a new treasure hunt. It argues that while we usually look for this missing 95% in giant particle smashers (like the Large Hadron Collider), we might find the clues much more easily by looking at neutrinos.
Neutrinos are ghostly, tiny particles that pass through everything. They are already known to be weird because they change "flavors" (like a chameleon changing colors) as they travel. This paper suggests that neutrino facilities—places where we create or catch these ghosts—are actually the perfect "crime scenes" to find new physics.
Here is a breakdown of the paper's main ideas using simple analogies:
1. The Two Types of "Clues"
The paper divides the search for new physics into two main categories, based on where the "suspects" (new particles) come from:
The "Factory" Clues (Laboratory-Produced):
Imagine a high-speed train station (an accelerator) or a power plant (a reactor). When protons or electrons smash into targets, they create a massive shower of particles. The paper suggests that hidden in this chaotic shower, new, exotic particles might be born.- The Analogy: It's like shaking a snow globe. Most of the snow is just regular snow (standard particles), but if you shake it hard enough, you might find a hidden golden coin (a dark matter particle or a new force carrier) mixed in. Because we control the shaking (the beam), we know exactly when and where to look for the coin.
- Key Players: Experiments like DUNE, T2K, and SHiP are building specialized "nets" right next to these factories to catch these coins before they disappear.
The "Cosmic Drift" Clues (Cosmogenic Signals):
Sometimes, the new particles aren't made in a lab; they are drifting in from deep space, the sun, or even the center of our galaxy.- The Analogy: Imagine standing on a beach with a giant net. You aren't making the fish; you are waiting for them to swim by from the ocean. Some fish might be regular fish, but others might be rare, glowing sea creatures (like "Boosted Dark Matter") that only show up when the cosmic waves hit just right.
- Key Players: Giant detectors like IceCube (in the Antarctic ice) and Super-Kamiokande (a giant water tank in Japan) act as these nets, waiting for these cosmic visitors.
2. The "Ghost Hunters" (The Experiments)
The paper highlights a massive global effort, with a special spotlight on East Asia (Korea, Japan, China). Think of these experiments as different types of specialized detectives:
- The "Microscope" Detectives (Small, Precise):
Experiments like DAMSA and JSNS2 are like high-powered microscopes. They are small, sit very close to the particle source, and look for tiny, specific glitches in the data. They are looking for things like "sterile neutrinos" (ghosts that don't even interact with the weak force) or "dark photons" (a dark version of light). - The "Giant Net" Detectives (Big, Powerful):
Experiments like Hyper-Kamiokande (a massive water tank) and JUNO (a giant liquid scintillator sphere in China) are like giant fishing nets. They wait for rare events, like a supernova (a dying star) exploding nearby, or they look for the faint glow of dark matter particles hitting the water. - The "Forward Look" Detectives (LHC/HL-LHC):
At the world's biggest particle collider, there are detectors like FASER and SND that look "forward" down the tunnel. They are like people standing at the end of a hallway, catching particles that fly straight ahead, which are often the ones carrying the most exotic secrets.
3. The "East Asian Engine"
A major theme of this paper is that East Asia is becoming the engine room for this new physics.
- Korea is building a new underground lab called Yemilab, which will host a multi-purpose detector called νEYE. Think of νEYE as a Swiss Army knife detector: it can look at reactor neutrinos, solar neutrinos, and even act as a "beam dump" to catch dark matter.
- Japan is upgrading its T2K experiment and building Hyper-Kamiokande.
- China is operating JUNO, which is trying to solve the mystery of why neutrinos have mass.
The paper argues that these facilities are not just competing; they are complementary. It's like having a team of detectives where one has a magnifying glass, another has a telescope, and a third has a radar. Together, they can solve the case that none of them could solve alone.
4. The "Toolbox" Needed
The paper concludes by saying that to catch these ghosts, we need better tools.
- Better Cameras: We need detectors that can see very faint signals (low energy thresholds) and tell the difference between a regular particle and a weird new one (particle identification).
- Better Timing: We need clocks that tick faster than a nanosecond to separate the "signal" from the "noise."
- Better Simulations: We need computer programs that can perfectly mimic what happens in the detector so we know what a "normal" event looks like. If we know what "normal" looks like, any weirdness stands out immediately.
The Bottom Line
This paper is a call to action. It says: "Stop looking only at the big particle smashers. The neutrino facilities around the world, especially the new ones in East Asia, are the perfect places to find the missing 95% of the universe."
It's not just about finding one new particle; it's about using the unique properties of neutrinos to open a new window into the dark sector of the universe. The paper outlines the roadmap, the tools, and the global team required to make this discovery in the coming decades.
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