electron positron pair

When a laser beam hits a gas, it tears electrons from atoms and accelerates them to nearly the speed of light. As these electrons fly through the plasma, they emit X-rays, like a glowing trail from a fast particle. In the new work, physicists made a single laser pulse create not one but two such trails in succession.

When a ψ(2S) particle decays into a proton and an antiproton, two different mechanisms act simultaneously: the strong interaction, like glue holding quarks together, and the electromagnetic one, like light pushing charges apart. Their contributions add up with a certain phase shift.

The helium atom is like a tightly stretched string: every note it plays is strictly predicted by theory. But in recent years, precise measurements of one such "note"—the energy needed to strip an electron from an excited helium atom — have started to sound slightly higher than they should.

The antiproton is the mirror twin of the proton: same mass, but negative charge. When it hits matter, it usually annihilates instantly — disappearing in a burst of energy upon colliding with an atomic nucleus.

A spinning top whirls so fast that the air around it starts to rotate in unison. A black hole behaves in much the same way: if it spins, it can transfer its energy to particles that happen to be nearby. This process is called superradiance: it's like an echo in the mountains, but instead of sound, new particles are born.

Water in a glass looks continuous, but it's made of molecules. Similarly, physicists have long described the matter inside a neutron star as a uniform soup of protons and neutrons. But real neutron stars are not soup. They are a dense crowd of particles where each neutron feels its neighbors. The authors of the new work abandoned the uniform picture.

In a quiet room, you can hear the faintest whisper. Likewise, in the hydrogen atom, the lightest of all, an uninvited guest is easier to spot. That guest could be the Z' boson, a mediator particle of a new force predicted by many unification theories. The Standard Model already has its own mediator — the Z boson.

The mystery of antimatter in space has long puzzled astrophysicists: where do positrons come from, settling like snowflakes into our detectors? The answer might lurk in the most ubiquitous gamma-ray background. The Universe is soaked in diffuse light — the cosmic photon background (CPB).

Imagine a green beam that, passing through an ingenious optical setup, twists into a three-dimensional funnel of light — an optical vortex. At its heart, like in the eye of a hurricane, the intensity drops to zero. It is there that photons disappear.

In 2021, the LHAASO observatory registered gamma quanta with energies above a petaelectronvolt from sources like the Crab Nebula — a supernova remnant with a pulsating neutron star at its heart.

Light hits an organic molecule, and inside, a pair of twin excitations is born. They're called triplet pairs. In single pentacene molecules, such pairs have long been known to share their energy with neighbors: this is the basis of singlet fission, which boosts the efficiency of solar cells.

Boson stars are gravitational atoms. Only instead of electric charge, gravity itself serves as the nucleus, holding a cloud of scalar field in quantized clumps.

An electron and its antiparticle — the positron, predicted by Дираком, — upon meeting, momentarily form позитроний: a tiny pair circling each other, like in an atom but without a nucleus. Almost instantly it decays, emitting two photons that turn out to be mysteriously linked.

In very dim light, photons arrive one by one, like drops from a leaky faucet — never in pairs. This effect, predicted by Roy Glauber and confirmed by Leonard Mandel, directly proves that light is made of particles.

A neutron star is the leftover core of an exploded giant, compressed to the size of a city. A teaspoon of its matter weighs a billion tons. Inside such a star, particles are packed so tightly that quantum effects start to show. One of them is the intrinsic rotation of particles, or spin.

A regular flashlight shines equally forward and backward. But in magnetic crystals, a axion appears — a ghostly excitation, like a wave going around a stadium: atoms pass a magnetic impulse to each other. When light meets an axion, a hybrid forms, whose fate depends on electric and magnetic fields.

Two massive spheres slowly drift apart in empty space. From the standpoint of ordinary mechanics, nothing special is happening. But Einstein's equations say otherwise: accelerating masses stir spacetime itself, and from them spread gravitational waves — ripples that stretch and squeeze everything in their path.

Two neutron stars (the remnants of dead stars, compressed to the size of a city but weighing as much as the Sun) spiral around each other and eventually collide. At that moment, something between a black hole and a super-powered magnet is born: a field billions of times stronger than that of the most powerful MRI machine.

Many black holes are surrounded by magnetic fields. As it spins, the black hole drags curved spacetime along with it, like a machine's flywheel, and sets the cosmic factory in motion.

Physicists have proposed an experiment: a laser beam acts as a quantum detector and splits into two beam-ears. Each ear is directed through a tiny cloud of ultracold atoms — in this state, atoms merge into a single wave.

Two electrically charged spheres attract each other with a certain force. If you replace their charges with magnetic poles, a spring scale shows exactly the same force. Black holes, it turns out, behave the same way — except instead of springs, the fabric of spacetime itself does the work.

The pendulum of an old clock swings because a spring mechanism gives it a regular nudge. Now imagine a pendulum that decides on its own when to swing, and does so with a steady rhythm, just because the room is warm and there's a slight draft. That's exactly how time crystals behave, born in clumps of light and matter inside a semiconductor chip.

A translator halfway across the hall suddenly starts rendering the message backwards. That's roughly how a neutrino, a ghost particle that barely notices matter, might behave if it encounters a cloud of ultralight dark matter.

A pinch of salt falls into water, and sodium and chlorine ions scatter, surrounded by water molecules. Now, instead of an ion, a positron (an antiparticle, the electron's twin but with a plus instead of a minus) joins the molecular crowd.

A juggler tosses clubs while sitting on a spinning chair. If he starts spinning the clubs all in one direction, the chair will rotate the opposite way — otherwise, the conservation of angular momentum would be violated.

If you squeeze a handful of sand in your fist, it first compacts, but then starts to resist — the grains have nowhere left to go. In the depths of a neutron star, something similar happens, except instead of sand grains, you have elementary particles, and instead of your hand, you have monstrous gravity.

In a packed hall where couples are spinning, a wave sometimes ripples through: some pairs break apart, others form, and the motion sweeps everyone along. A dense neutrino cloud behaves similarly: these are the tiniest particles that barely interact with matter.

A stack of magnetic plates, each magnetized opposite to its neighbor, is like a layered sandwich where electrons move as a single organism. The whole material starts mimicking an axion — a ghost particle that physicists suspect might be dark matter.

A copper wire under current is a familiar sight, but inside it something unexpected is happening. A strong electric current doesn't just heat the metal: it knocks atoms out of their rightful places, leaving behind tiny voids, as if a few balls were suddenly removed from a tightly packed arrangement.

Inside a neutron star, the density doesn't change smoothly but drops abruptly at sharp cliffs — density staircases. At these steps, the void suddenly births pairs: neutrinos and antineutrinos.

According to the Standard Model, the vacuum is not emptiness but an ocean of virtual ghost particles. An ultra-strong electromagnetic field, like a storm, yanks electron-positron pairs into reality.

To uncover the proton's true size, physicists swapped the electron in a hydrogen atom for its heavy copy — the muon. Acting like a magnifying glass with thousandfold power, the muon gets right up against the nucleus and 'probes' the proton with unprecedented precision.

When particles collide at enormous speeds, they produce a shower of new particles. Among them are antiprotons — twins of ordinary protons but with the opposite charge. Each of these particles has its own spin, like a tennis ball sent with a twist. But whether antiprotons are actually spun up at birth has never been checked.

When two particles fly at almost the same speed in the same direction, their signals in the detector merge, like two voices in unison. Telling a duet from a soloist is an art in itself.

A ring road around the Sun, where the traffic is not cars but clumps of matter. The diameter of this road is measured in light-years: it encircles our planetary system at its outer edge, in the Oort Cloud, where the star's weak gravity still holds sway.

In the first instants after the big bang, the universe was a quantum vacuum where pairs of particles and antiparticles, virtual "guests" from physical nothingness, spontaneously appeared and almost immediately annihilated.

Inside a barium titanate crystal, there's a built-in electric field, like a permanent magnet, but for charges. When a flash of light hits it, electrons are knocked loose and start darting around, colliding with atoms. But the crystal isn't the same in all directions: it has an axis along which the field is strongest.

The universe wasn't born alone — alongside it came a mirror twin where everything is reversed: left and right are swapped and time flows from future to past. After the Big Bang, the world, according to Alan Guth's idea of superfast inflation, should have contained equal amounts of matter and antimatter.

A quantum dot the size of a virus, squeezed between mirrors, gives birth to two photons in a short flash of light. These photons fly out as a pair, and their polarizations, the directions of wave oscillation, are linked such that knowing one instantly tells you the other.

Two tiny emitters, each about the size of an atom, can together do what neither can do alone. We're talking about light scattering — when light hits particles and bounces off in all directions. Usually, a pair of particles scatters light only slightly more than a single one.