A team of researchers with The NNPDF Collaboration has found new evidence to support the theory of "intrinsic" charm quarks. In their paper published in the journal Nature, the group describes how they used a machine learning model to develop a proton structure and then used it to compare against results from real-world collisions in particle accelerators and what they learned by doing so. Ramona Vogt, with Lawrence Livermore National Laboratory has published a News & Views piece in the same journal issue outlining the work by the team on this new effort. Nature has also published a podcast where Nick Petrić Howe and Benjamin Thompson discuss the work done by the team.

The textbook description of a proton says it contains three smaller particles - two up quarks and a down quark - but a new analysis has found strong evidence that it also holds a charm quark

Over the course of the 20th century, physicists have discovered numerous elementary particles. The largest family of these particles are the so-called hadrons, subatomic particles that take part in strong interactions.

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 bind together into these composite particles.

They hope they will help us understand the "strong force" that holds the insides of atoms together.

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Scientists studying particle collisions at the Relativistic Heavy Ion Collider (RHIC) have revealed how certain particle-jets lose energy as they traverse the unique form of nuclear matter created in these collisions. The results, published in Physical Review C, should help them learn about key "transport properties" of this hot particle soup, known as a quark-gluon plasma (QGP).

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 experiments performed at the Large Hadron Collider (LHC) operated by the European Organization for Nuclear Research (CERN), the confinement is interrupted and the quarks and gluons scatter, forming a plasma. The phenomenon lasts only a tiny fraction of a second, but observation of it has produced important discoveries about the nature of material reality.

Author(s): Fabrizio Caola, Amlan Chakraborty, Giulio Gambuti, Andreas von Manteuffel, and Lorenzo TancrediThree-loop corrections to a complicated four-parton scattering amplitude in full QCD will aid precision calculations at hadron colliders. [Phys. Rev. Lett. 128, 212001] Published Thu May 26, 2022

Author(s): Diogo Boito, Maarten Golterman, Kim Maltman, and Santiago PerisTheory predictions for g-2, the muon’s anomalous magnetic moment, can be made with dispersive methods or with lattice calculations, but some current estimates show tension between the two. This becomes especially important in view of the apparent discrepancy with the experimental value. The authors of this Suggestion show how a subset of contributions to the hadronic vacuum polarization, the leading source of theory uncertainty, can be related to physical observables. The results can help isolate the disagreement between the differing calculations. [Phys. Rev. D 105, 093003] Published Mon May 16, 2022

The CMS collaboration at the Large Hadron Collider (LHC) has performed the most accurate ever measurement of the mass of the top quark—the heaviest known elementary particle. The latest CMS result estimates the value of the top-quark mass with an accuracy of about 0.22%. The substantial gain in accuracy comes from new analysis methods and improved procedures to consistently and simultaneously treat different uncertainties in the measurement.

Since the discovery of the Higgs boson a decade ago, the ATLAS and CMS collaborations at the Large Hadron Collider (LHC) have been hard at work trying to unlock the secrets of this special particle. In particular, the collaborations have been investigating in detail how the Higgs boson interacts with fundamental particles such as the particles that make up matter, quarks and leptons. In the Standard Model of particle physics, these matter particles fall into three "generations" of increasing mass, and the Higgs boson interacts with them with a strength that is proportional to their mass. Any deviation from this behavior would provide a clear indication of new phenomena.

Physicists have found evidence of X particles in the quark-gluon plasma produced in the Large Hadron Collider (LHC) at CERN, the European Organization for Nuclear Research, based near Geneva, Switzerland.

The findings could redefine the kinds of particles that were abundant in the early universe.

The findings could redefine the kinds of particles that were abundant in the early universe. In the first

In the first millionths of a second after the Big Bang, the universe was a roiling, trillion-degree plasma of quarks and gluons—elementary particles that briefly glommed together in countless combinations before cooling and settling into more stable configurations to make the neutrons and protons of ordinary matter.

University of Adelaide experts, who are part of the international community of researchers investigating the fundamental physical properties of atoms, may have come across a new paradigm for the way atomic nuclei are built.

The predicted existence of an exotic particle made up of six elementary particles known as quarks by RIKEN researchers could deepen our understanding of how quarks combine to form the nuclei of atoms.

Author(s): Tyler Gorda, Aleksi Kurkela, Risto Paatelainen, Saga Säppi, and Aleksi VuorinenIn a tour de force calculation, using new computational techniques, the authors compute the contribution of soft gluons, gluons with momenta smaller than the Debye screening mass, to the pressure of cold nuclear matter, a QCD medium at zero temperature but large chemical potential, at next-to-next-to-next-to-leading order. [Phys. Rev. D 104, 074015] Published Fri Oct 15, 2021

Two independent studies have illuminated unexpected substructures in the fundamental components of all matter. Preliminary results using a novel tagging method could explain the origin of the longstanding nuclear paradox known as the EMC effect. Meanwhile, authors will share next steps after the recent observation of asymmetrical antimatter in the proton.

Two independent studies have illuminated unexpected substructures in the fundamental components of all matter. Preliminary results using a novel tagging method could explain the origin of the longstanding nuclear paradox known as the EMC effect. Meanwhile, authors will share next steps after the recent observation of asymmetrical antimatter in the proton.

Scientists seeking to explore the teeming microcosm of quarks and gluons inside protons and neutrons report new data delivered by particles of light. The light particles, or photons, come directly from interactions of a quark in one proton colliding with a gluon in another at the Relativistic Heavy Ion Collider (RHIC). By tracking these 'direct photons,' scientists say they are getting a glimpse -- albeit a blurry one -- of gluons' transverse motion within the building blocks of atomic nuclei.

Visible matter, or the stuff that composes the things we see, is made of particles that can be thought of much like building blocks made of more building blocks, ever decreasing in size, down to the sub-atomic level. Atoms are made of things like protons and neutrons, which are composed of even smaller building blocks such as quarks. Studying those smallest building blocks requires experimentation where atomic particles are accelerated and broken apart, then theoretical work to understand and describe what happened.

The rare tetraquark is one of dozens of non-elementary particles discovered at the accelerator, and could help test theories about the strong nuclear force -- Read more on ScientificAmerican.com

A new special edition of EPJ Special Topics brings together several papers that detail our understanding of Quark-Gluon Plasma (QGP) and the processes that transformed it into the baryonic matter we around us on an everyday basis.

In the early stages of the Universe, quarks and gluons were quickly confined to protons and neutrons which went on to form atoms. With particle accelerators reaching increasingly higher energy levels the opportunity to study this fleeting primordial state of matter has finally arrived.

Today, the LHCb experiment at CERN is presenting a new discovery at the European Physical Society Conference on High Energy Physics (EPS-HEP). The new particle discovered by LHCb, labeled as Tcc+, is a tetraquark—an exotic hadron containing two quarks and two antiquarks. It is the longest-lived exotic matter particle ever discovered, and the first to contain two heavy quarks and two light antiquarks.

Unique among its peers is the top quark—a fascinating particle that the scientific community has been studying in detail since the 90s. Its large mass makes it the only quark to decay before forming bound states (a process known as hadronisation) and gives it the strongest coupling to the Higgs boson. Theorists predict it may also interact strongly with new particles—if it does, the Large Hadron Collider (LHC) is the ideal place to find out as it is a "top-quark factory."

On the 14th of August 2019, the LIGO-Virgo collaboration detected a gravitational wave signal believed to be associated with the merging of a binary stellar system composed of a black hole with a mass of 23 times the mass of the sun (M⊙) and a compact object with a mass of about 2.6 M⊙. The nature of GW190814ʼs secondary star is enigmatic, since, according to the current astronomical observations, it could be the heaviest neutron star or the lightest black hole ever observed.

What does quark-gluon plasma - the hot soup of elementary particles formed a few microseconds after the Big Bang - have in common with tap water? Scientists say it's the way it flows.

What does quark-gluon plasma—the hot soup of elementary particles formed a few microseconds after the Big Bang—have in common with tap water? Scientists say it's the way it flows.

Author(s): S. Demirci, T. Lappi, and S. SchlichtingIn this paper, the authors study the origin of eccentricity, or more generally, the azimuthal asymmetry in the initial conditions of small colliding systems, such as the proton nucleus system. Of the contending sources, namely color charge fluctuations and the geometric fluctuation of the so called hot spots in the proton, they conclude that the latter is by far the dominant cause of the asymmetry. [Phys. Rev. D 103, 094025] Published Fri May 21, 2021

When it comes to quarks, those of the third generation (the top and bottom) are certainly the most fascinating and intriguing. Metaphorically, we would classify their social life as quite secluded, as they do not mix much with their relatives of the first and second generation. However, as the proper aristocrats of the particle physics world, they enjoy privileged and intense interactions with the Higgs field; it is the intensity of this interaction that eventually determines things like the quantum stability of our universe. Their social life may also have a dark side, as they could be involved in interactions with dark matter.

CERN's Large Hadron Collider (LHC) is famous for colliding protons at world-record energies—but sometimes it pays to dial down the energy and see what happens under less extreme conditions. The LHC started operation in 2010 with a collision energy of 7 TeV, and ran at 13 TeV from 2015 to 2018. But for one week in 2017, the LHC produced moderate-intensity collisions at only 5 TeV—allowing scientists to analyze the production of various elementary particles at a lower collision energy.

A new review examines the three decades of the LHCb experiment, its achievements and future potential.

A new review published in The European Physical Journal H by Clara Matteuzzi, Research Director at the National Institute for Nuclear Physics (INFN) and former tenured professor at the University of Milan, and her colleagues, examines almost three decades of the LHCb experiment—from its conception to operation at the Large Hadron Collider (LHC) - documenting its achievements and future potential.

A never-before-seen particle known as the odderon has revealed itself in the hot guts of two particle colliders, confirming a 48-year-old theory.

Author(s): Sophia ChenThe detection of a new particle containing both charm and strange quarks could offer new insights into how hadrons form. [Physics 14, s33] Published Thu Mar 11, 2021

Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.

In “Fundamentals,” Frank Wilczek describes his own love for physics and details what we all need to understand about the forces that shape our physical world.

Author(s): Mark P. Hertzberg, Fabrizio Rompineve, and Jessie YangMassive real scalar particles, for instance glueballs from a posited hidden sector, are interesting dark matter candidates. If they possess repulsive self interactions that can oppose gravity, they can potentially clump into massive boson stars. The authors show that the same repulsive self interactions also mediate number changing annihilation processes, which may preclude the existence of these stars for cosmologically relevant times and would exclude the parameter space where such stars could provide interesting gravitational wave signatures. [Phys. Rev. D 103, 023536] Published Wed Jan 27, 2021

The Compact Muon Solenoid (CMS) Collaboration, a large group of researchers from different institutes worldwide, has recently gathered the very first evidence of top quark production in nucleus-nucleus collisions. Their work, outlined in a paper published in Physical Review Letters, was based on lead-lead collision data gathered by the CMS particle detector, at CERN's Large Hadron Collider (LHC).

Matter is built around quarks, forming the nuclei of the atoms and molecules. While there are six types of quarks, regular matter contains only two: up quarks and down quarks. Protons contain two ups and a down, while neutrons contain two downs and an up. On Earth, the other four types are only seen when created in particle accelerators. But some of them could also appear naturally in dense objects such as neutron stars.

The positively charged protons in atomic nuclei should actually repel each other, and yet even heavy nuclei with many protons and neutrons stick together. The so-called strong interaction is responsible for this. Prof. Laura Fabbietti and her research group at the Technical University of Munich (TUM) have now developed a method to precisely measure the strong interaction utilizing particle collisions in the ALICE experiment at CERN in Geneva.

The strong interaction is one of the fundamental forces of nature, which binds quarks into hadrons such as the proton and the neutron, the building blocks of atoms. According to the quark model, hadrons can be formed by two or three quarks, called mesons and baryons respectively, and collectively referred to as conventional hadrons. The quark model also allows for the existence of so-called exotic hadrons, composed by four (tetraquarks), five (pentaquarks) or more quarks. A rich spectrum of exotic hadrons is expected just as for the conventional ones. However, no unambiguous signal of exotic hadrons was observed until 2003, when the X(3872) state was discovered by the Belle experiment. In the following years, a few more exotic states were discovered. The explanation of their properties requires the existence of four constituent quarks. Identification of pentaquark states is even more difficult, and the first candidates were observed by the LHCb experiment in 2015. All these known

The result of recent research by the CMS collaboration opens the path to study in a new and unique way an extreme state of matter that is thought to have existed shortly after the Big Bang. The collaboration has seen evidence of top quarks in collisions between heavy nuclei at the Large Hadron Collider (LHC).

The quantum chromodynamics phase transition in core-collapse supernovae has been examined for the first time, using state-of-the-art multi-dimensional supernova simulations and unique imprints of such a phase transition on the emitted gravitational-wave and neutrino signals have been detected.

The LHCb experiment at CERN has developed a penchant for finding exotic combinations of quarks, the elementary particles that come together to give us composite particles such as the more familiar proton and neutron. In particular, LHCb has observed several tetraquarks, which, as the name suggests, are made of four quarks (or rather two quarks and two antiquarks). Observing these unusual particles helps scientists advance our knowledge of the strong force, one of the four known fundamental forces in the universe. At a CERN seminar held virtually on 12 August, LHCb announced the first signs of an entirely new kind of tetraquark with a mass of 2.9 GeV/c²: the first such particle with only one charm quark.

Nuclear physicists are trying to understand how particles called quarks and gluons combine to form hadrons, composite particles made of two or three quarks. To study this process, called hadronization, a team of nuclear physicists used the STAR detector at the Relativistic Heavy Ion Collider—a U.S. Department of Energy Office of Science user facility for nuclear physics research at DOE's Brookhaven National Laboratory—to measure the relative abundance of certain two- and three-quark hadrons created in energetic collisions of gold nuclei. The collisions momentarily "melt" the boundaries between the individual protons and neutrons that make up the gold nuclei so scientists can study how their inner building blocks, the quarks and gluons, recombine.

Physicists have discovered a new, exotic kind of tetraquark, made up of four charm quarks. They say it's a major breakthrough.

Adding an exotic particle known as a Xi hyperon to a helium nucleus with three nucleons could produce a nucleus that is temporarily stable, calculations by RIKEN nuclear physicists have predicted. This result will help experimentalists search for the nucleus and provide insights into both nuclear physics and the structure of neutron stars.

The ATLAS Collaboration at CERN has announced strong evidence of the production of four top quarks. This rare Standard Model process is expected to occur only once for every 70 thousand pairs of top quarks created at the Large Hadron Collider (LHC) and has proven extremely difficult to measure.

The world's largest atom smasher has "given birth" to a set of four ultraheavy particles — called top quarks.

Neutron stars are strange things. They can form when gravity kills a star, crushing its remains into a

When a particle is transformed into its antiparticle and its spatial coordinates inverted, the laws of physics are required to stay the same—or so we thought. This symmetry—known as CP symmetry (charge conjugation and parity symmetry) – was considered to be exact until 1964, when a study of the kaon particle system led to the discovery of CP violation.

Two ways of approximating the ultra-complicated math that governs quark particles have recently come into conflict, leaving physicists unsure what their decades-old theory predicts.

According to modern particle physics, matter produced when neutron stars merge is so dense that it could exist in a state of dissolved elementary particles. This state of matter, called quark-gluon plasma, might produce a specific signature in gravitational waves. Physicists have now calculated this process using supercomputers.

Computer models of merging neutron stars predicts how to tell when this happens.

Neutron stars are among the densest objects in the Uiverse. If our Sun, with its radius of 700,000 kilometres were a neutron star, its mass would be condensed into an almost perfect sphere with a radius of around 12 kilometres. When two neutron stars collide and merge into a hyper-massive neutron star, the matter in the core of the new object becomes incredibly hot and dense. According to physical calculations, these conditions could result in hadrons such as neutrons and protons, which are the particles normally found in our daily experience, dissolving into their components of quarks and gluons and thus producing a quark-gluon plasma.

A quarter-century after its discovery, physicists at the ATLAS Experiment at CERN are gaining new insight into the heaviest-known particle, the top quark. The huge amount of data collected during Run 2 of the LHC (2015-2018) has allowed physicists to study rare production processes of the top quark in great detail, including its production in association with other heavy elementary particles.

Most ordinary matter is held together by an invisible subatomic glue known as the strong nuclear force—one of the four fundamental forces in nature, along with gravity, electromagnetism, and the weak force. The strong nuclear force is responsible for the push and pull between protons and neutrons in an atom's nucleus, which keeps an atom from collapsing in on itself.

Author(s): Constantia Alexandrou, Joshua Berlin, Jacob Finkenrath, Theodoros Leontiou, and Marc WagnerThe authors explore the content of the D s 0 * ( 2317 ) meson in a lattice QCD study. Using several local two-quark, local tetraquark, and two-meson, i.e. molecular, interpolating fields, they find that the tetraquark contribution to the D s 0 * ( 2317 ) meson

The world around us is populated by a vast variety of things—ranging from genes and animals to atoms, particles and fields. While these can all be described by the natural sciences, it seems some can only be understood in terms of biology while others can only be explored using chemistry or physics. And when it comes to human behavior, disciplines like sociology or psychology are the most useful.

At the Large Hadron Collider (LHC) at CERN, the electromagnetic fields of Lorentz-contracted lead nuclei in heavy-ion collisions act as intense sources of high-energy photons, or particles of light. This environment allows particle physicists to study photon-induced scattering processes, which can not be studied elsewhere.

Data from Compact Muon Solenoid (CMS) used to better understand one of the fundamental building blocks of matter.

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology.

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology.

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology, report physicists at the University of Basel and Ruhr-University Bochum in the journal Nature.

For the first time, CMS physicists have investigated an effect called the "running" of the top quark mass, a fundamental quantum effect predicted by the Standard Model.

New findings from University of Kansas experimental nuclear physicists Daniel Tapia Takaki and Aleksandr (Sasha) Bylinkin were just published in the European Physical Journal C. The paper centers on work at the Compact Muon Solenoid, an experiment at the Large Hadron Collider, to better understand the behavior of gluons.

There are some odd little particles out there that are bound by the strong nuclear force, but physicists can barely get a glimpse of them before they flit out of existence.

As the heaviest known particle, the top quark plays a key role in studies of fundamental interactions. Due to its short lifetime, the top quark decays before it can turn into a hadron. Thus, its properties are preserved and transferred to its decay products, which can in turn be measured in high-energy physics experiments. Such studies provide an excellent testing ground for the Standard Model and may provide clues for new physics.

As the heaviest known elementary particle, the top quark has a special place in the physics studied at the Large Hadron Collider (LHC) at CERN. Top quark-antiquark pairs are copiously produced in collisions recorded by the ATLAS detector, providing a rich testing ground for theoretical models of particle collisions at the highest accessible energies. Any deviations between measurements and predictions could point to shortcomings in the theory – or first hints of something completely new.

Among the most intriguing particles studied by the ATLAS Experiment is the top quark. As the heaviest known fundamental particle, it plays a unique role in the Standard Model of particle physics, and perhaps in physics beyond the Standard Model.

Forty years ago, in 1979, experiments at the DESY laboratory in Germany provided the first direct proof of the existence of gluons—the carriers of the strong force that "glue" quarks into protons, neutrons and other particles known collectively as hadrons. This discovery was a milestone in the history of particle physics, as it helped establish the theory of the strong force, known as quantum chromodynamics.

A team of researchers working on the LHCb collaboration has found evidence showing that a pentaquark they have observed has a molecule-like structure. In their paper published in the journal Physical Review Letters, the group describes the evidence and the structure of the pentaquark they observed.

The pentaquark, an elusive particle first spotted by the Large Hadron Collider in 2015, is made of two smaller particles stuck together in a sort of miniature molecule

Presumed "bags of quarks" may actually be more like atomic nuclei

New Large Hadron Collider data reveal that exotic quark quintets, discovered in 2016, are composites of quark-antiquark mesons and three-quark baryons.   [Physics] Published Wed Jun 05, 2019

Author(s): R. Aaij et al. (LHCb Collaboration)New Large Hadron Collider data reveal that exotic quark quintets, discovered in 2016, are composites of quark-antiquark mesons and three-quark baryons. [Phys. Rev. Lett. 122, 222001] Published Wed Jun 05, 2019

Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.

To commemorate the 50th anniversary of Murray Gell-Mann’s first paper on quarks, Gell-Mann biographer George Johnson has written several terrific posts about one of the truly great theoristsand... -- Read more on ScientificAmerican.com

In 2018, the ATLAS and CMS Collaborations at CERN announced the observation of the production of the Higgs boson in association with a top-quark pair, known as "ttH" production. This result was the first observation of the Higgs boson coupling to quarks. It was followed shortly by the observation of Higgs boson decays to bottom quarks.

Researchers now know what's going on inside mysterious particles called pentaquarks.

The LHCb collaboration has observed a new pentaquark particle and has confirmed the pentaquark structure previously reported. The

Tomasz Skwarnicki, professor of physics in the College of Arts and Sciences at Syracuse University, has uncovered new information about a class of particles called pentaquarks. His findings could lead to a new understanding of the structure of matter in the universe.

New data from the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) add detail -- and complexity -- to an intriguing puzzle that scientists have been seeking to solve: how the building blocks that make up a proton contribute to its spin. The results reveal that different 'flavors' of antiquarks contribute differently to the proton's overall spin -- and in a way that's opposite to those flavors' relative abundance.

Author(s): Lekha Adhikari, Yang Li, Meijian Li, and James P. VaryThe authors calculate electromagnetic observables for a selection of spin-1 heavy quarkonia using the basis light front quantization method. They solve the relativistic Hamiltonian mass eigenvalue problem in a convenient basis representation that provides a compact form of the eigenfunctions. The approach provides insight into the spin-sensitive structure and internal dynamics of hadrons at low and medium momentum transfer. [Phys. Rev. C 99, 035208] Published Fri Mar 15, 2019

New data from the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) add detail—and complexity—to an intriguing puzzle that scientists have been seeking to solve: how the building blocks that make up a proton contribute to its spin. The results, just published as a rapid communication in the journal Physical Review D, reveal definitively for the first time that different "flavors" of antiquarks contribute differently to the proton's overall spin—and in a way that's opposite to those flavors' relative abundance.

Quarks, the smallest particles in the universe, are far smaller and operate at much higher energy levels than

Physicists now know why quarks, the building blocks of the universe, move more slowly inside atomic nuclei, solving a 35-year-old-mystery.

MIT physicists now have an answer to a question in nuclear physics that has puzzled scientists for three

Author(s): Elias R. Most, L. Jens Papenfort, Veronica Dexheimer, Matthias Hanauske, Stefan Schramm, Horst Stöcker, and Luciano RezzollaTwo theoretical studies quantify how gravitational waves may serve as probes of phases of nuclear matter in neutron stars. [Phys. Rev. Lett. 122, 061101] Published Tue Feb 12, 2019

The top quark is about 100 trillion times heavier than the up quark. But why?

Scientists widely accept the existence of quarks, the elusive fundamental particles that make up protons and neutrons. But information about their properties is still lacking.