C. Lin

In 2016, the LHCb detector at the Large Hadron Collider recorded millions of proton-proton collisions. Among the debris of these collisions, neutral B mesons were born—particles that can spontaneously transform into their antiparticles and back.

In the crystal La₂₋ₓSrₓCuO₄, at a certain composition, two states coexist: superconductivity, where electrons move without loss, and a charge-density wave — a periodic bunching of electron density. These states compete for the same electron clouds, which resemble cross-shaped petals.

In the LHCb detector at the Large Hadron Collider, protons collide, and for a fleeting moment, particles that don't exist in ordinary matter are born. One of them is the neutral B meson. It lives for less than a billionth of a second and decays into two other particles: the narrow resonance J/ψ and the broader ρ(770).

In a giant particle accelerator, where protons traveling at nearly the speed of light smash into a neon target, charmed baryons are born — particles that live for less than a billionth of a second.

Proton collisions at the Large Hadron Collider produce particles that live for less than a billionth of a second. One of them is the Bs meson, made of a strange quark and a bottom antiquark.

In the LHCb detector, like in a giant camera with billions of 'snapshots,' rare events are captured: how short-lived particles, B mesons, fall apart into lighter ones. One such decay, where a B meson turns into a kaon and a pair of muons, is particularly interesting. In it, as in a mirror, the difference between matter and antimatter may show up.

The kaon is a long-lived particle by microcosm standards: it lives for billionths of a second before breaking apart into lighter particles. In the KOTO experiment in Japan, physicists catch the rarest variants of such decays. One of them is when a kaon transforms into two neutral pions plus another particle X, which immediately decays into two photons (particles of light).

Every second, billions of decays happen inside our bodies, and nobody notices. But physicists do: they smash particles in accelerators and watch what fragments they fly into. Hidden in those fragments is the answer to why we exist at all. Right after the Universe was born, there were equal amounts of particles and antiparticles, but today all we see around us is particles.

Imagine a balance scale with identical weights, yet one pan always tips lower. In the world of elementary particles, this imbalance is called CP violation: particles and their mirror twins (antiparticles) behave slightly differently.

In the LHCb detector, where protons collide, one unusual track was found among billions of decays. The particle, named $$D_{s1}$$(2933)^+, appears for a moment and immediately decays into other particles. Its lifetime is so short that it cannot be observed directly — only through its decay products can its existence be reconstructed.

A coin landing on its edge is about as rare as a heavy B meson decaying into a light pion and an electron-positron pair. Over a decade of collider operation, only a handful of such events have accumulated, but physicists have finally managed to spot them. The decay probability is about 2.4×10⁻⁸.

Earth is a closed book for those accustomed to leafing through pages with light. But to neutrinos, the invisible particles born in cosmic rays and barely remembering the prediction of Pauli, our planet is a braille script: each kilometer of depth presses its relief into their…

For almost a century, seismology has been the planet’s chief X-ray, probing the interior through elastic waves. But neutrinos, ghost particles predicted by Wolfgang Pauli, offer a different perspective.

Deep beneath the ice of the South Pole, nearly two and a half kilometers down, an unusual telescope is at work. It is not pointed at the sky but through the Earth. Its quarry: neutrinos, nearly elusive particles that pass through planets and stars without interacting with anything.