Charm Quark

They hold the keys to new physics. If only we could understand them.

Physicists from the LHCb Collaboration at CERN's Large Hadron Collider (LHC) have reported the first observation of the decay of the Bc+ meson into a J/ψ charm-anticharm quark bound state and a pair of pions, π+π0.

Einstein's most famous equation is E = mc², which describes the rest mass energy inherent to particles. But motion matters for energy, too.

Every proton contains three quarks: two up and one down. But charm quarks, heavier than the proton itself, have been found inside. How?

Quark–gluon plasma is an extremely hot and dense state of matter in which the elementary constituents—quarks and gluons—are not confined inside composite particles called hadrons, as they are in the protons and neutrons that make up the nuclei of atoms. Thought to have existed in the early universe, this special phase of matter can be recreated at the Large Hadron Collider (LHC) in collisions between lead nuclei.

The strong force binds quarks inside neutrons and protons, and holds atomic nuclei together.

Faster, better, stronger.

Quark-gluon plasma (QGP) is a state of matter existing at extremely temperatures and densities, such as those that occur in collisions of hadrons (protons, neutrons and mesons). Under so-called "normal" conditions, quarks and gluons are always confined in the structures that constitute hadrons, but when hadrons are accelerated to relativistic velocities and made to collide with each other, as they are in the…

The ALICE collaboration at the Large Hadron Collider (LHC) has made the first direct observation of the dead-cone effect—a fundamental feature of the theory of the strong force that binds quarks and gluons together into protons, neutrons and, ultimately, all atomic nuclei. In addition to confirming this effect, the observation, reported in a paper published today in Nature, provides direct experimental access to…

Long-awaited boosts to the world's most powerful collider could spur breakthroughs in the hunt for physics beyond the Standard Model

The J particle; a nitroglycerin engine

Two detector upgrades of ALICE, the dedicated heavy-ion physics experiment at the Large Hadron Collider (LHC), have recently been approved for installation during the next long shutdown of the LHC, which will take place from 2026 to 2028. The first one is an upgrade of the innermost three layers of the Inner Tracking System (ITS3), and the second is a new forward calorimeter (FoCal), optimized for photon detection…

When two lead ions collide at the Large Hadron Collider (LHC), they produce an extremely hot and dense state of matter in which quarks and gluons are not confined inside composite particles called hadrons. This fireball of particles—known as quark–gluon plasma and believed to have filled the universe in the first few millionths of a second after the Big Bang—expands and cools down rapidly. The quarks and gluons…

Here in our Universe, almost every combination of fundamental particles you can imagine will lead to an unstable state. Anything containing a strange, charm, bottom, or top quark will decay in…

An experiment that probed particles called gluons, which contain most of the mass of a proton, has revealed that a proton's radius alters depending on whether you look at the particle's charge or mass

The Standard Model is the modern physical understanding of three of the four forces of nature: electromagnetism, the strong nuclear force and the weak nuclear force.

The international LHCb collaboration at the Large Hadron Collider (LHC) has observed three never-before-seen particles: a new kind of "pentaquark" and the first-ever pair of "tetraquarks", which includes a new type of tetraquark. The findings, presented today at a CERN seminar, add three new exotic members to the growing list of new hadrons found at the LHC. They will help physicists better understand how quarks…

Operators of the ALICE detector have observed the first direct evidence of the "dead cone effect," allowing them to assess the mass of the elusive charm quark.

Symmetries make the world go round, but so do asymmetries. A case in point is an asymmetry known as charge–parity (CP) asymmetry, which is required to explain why matter vastly outnumbers antimatter in the present-day universe even though both forms of matter should have been created in equal amounts in the Big Bang.

Most of us, when we think about the Standard Model, think about the fundamental particles and forces that make up the Universe. That's not a bad thing; that's largely correct! Within the Standard…