Pions are hadrons, consisting of a quark and an antiquark.    From Wordnik.com.  [CDF Ghost Muons] Reference

There are six quarks (and their antiquark mirror images), and six leptons.    From Wordnik.com.  [Higgs 101] Reference

There they can switch identities time and time again, becoming another quark or an antiquark.    From Wordnik.com.  [The Nobel Prize in Physics 2008 - Illustrated Presentation] Reference

It decays, nearly instantly, into the heaviest quark-antiquark or lepton-antilepton pair it can.    From Wordnik.com.  [Bump Hunting (Part 1)] Reference

For every quark there is an antiquark in the same way as the electron has an antiparticle, the positron.    From Wordnik.com.  [The Nobel Prize in Physics 2004 - Information for the Public] Reference

These occurrences can be successfully interpreted as a gluon radiating away from a quark or an antiquark (fig. 3).    From Wordnik.com.  [The Nobel Prize in Physics 2004 - Information for the Public] Reference

The tracing is of the overall occillation frequency … NOT a profile of overall quark/antiquark occillation behavior.    From Wordnik.com.  [Incompatible Arrows, IV: F. Scott Fitzgerald] Reference

These probabilities agree very well with measured data (e – = electron, e+ = positron, q = quark, q with overscore = antiquark, g = gluon).    From Wordnik.com.  [The Nobel Prize in Physics 2004 - Information for the Public] Reference

Quarks come in 3 “colours”, but the hadrons strongly-interacting particles we observe are colour-neutral: baryons are composed of 3 quarks of different colours, and mesons are quark-antiquark pairs.    From Wordnik.com.  [Your Favorite Conservatives on Evolution and ID - The Panda's Thumb] Reference

The subsample in question came to light in the course of the measurement of the b quark pair production cross section, which is proportional to the rate at which events with a b quark and a b antiquark are produced.    From Wordnik.com.  [CDF Ghost Muons] Reference

Admittedly, when the quarks have moved away from each other, they are influenced by increasingly strong forces that eventually lead to the creation of new quark-antiquark particles, and a shower of particles arises in the direction of the original quarks and antiquarks respectively.    From Wordnik.com.  [The Nobel Prize in Physics 2004 - Information for the Public] Reference

Quanta devoid of internal structure (such as quarks, leptons, and intermediate bosons) are the result of interaction with one quantum of space; particles endowed with internal structure (baryons constituted of three quarks and mesons made up of a quark-antiquark pair) are the product of interaction with several QS.    From Wordnik.com.  [Ervin Laszlo : EARTH, LIFE, AND MIND : THE PROMISE OF THE NEW HOLISM IN THE SCIENCES] Reference

A neutral pion is a quark-antiquark combination, and since they are the same.    From Wordnik.com.  [Discover Blogs] Reference

For example, a Higgs boson may split into a virtual top quark-antiquark pair.    From Wordnik.com.  [The Reference Frame] Reference

Baryons are made of three quarks, whereas mesons consist of a quark and an antiquark.    From Wordnik.com.  [American Scientist Online] Reference

The A meson is one of a family of 30 elementary particles composed of a quark and an antiquark.    From Wordnik.com.  [TheState.com: Homepage] Reference

Quark-antiquark pairs can pop up and momentarily transform a proton into a different, more exotic particle.    From Wordnik.com.  [New Scientist - Online News] Reference

The quarks always be found couples on particle groups called meson (consist of quark and antiquark) and baryon (consist from three quarks).    From Wordnik.com.  [ReadABlog.com New Blogs and RSS Feeds] Reference

Artist's rendering of the inner structure of a proton showing quarks and quark-antiquark pairs, with springs showing the gluons that bind the quarks.    From Wordnik.com.  [PhysOrg.com - latest science and technology news stories] Reference

Mesons form a bound state of a quark and antiquark pair, whereas baryons (including protons and neutrons) are made up of three quarks or three antiquarks.    From Wordnik.com.  [physicsworld.com: all content] Reference

With Goldhaber doing the bulk of the data analysis, the team in 1974 announced the discovery of a particle composed of the previously unknown charm quark and charm antiquark.    From Wordnik.com.  [TheState.com: Homepage] Reference

A proton-antiproton collision can produce a single top quark in two different ways: a quark and an antiquark can create a W boson, which then decays into a top quark and an anti-bottom quark.    From Wordnik.com.  [PhysOrg.com - latest science and technology news stories] Reference

For example, a quark in one proton hitting an antiquark in the other proton with, say, a couple hundred GeV can produce two jets of 100 GeV going in opposite directions (from the beam's eye view).    From Wordnik.com.  [Discover Blogs] Reference

This is because a light particle such as the Upsilon, created in a proton-proton collision in the forward or backward direction, implies that a medium-momentum quark hit a very small-momentum antiquark.    From Wordnik.com.  [Scientific Blogging] Reference

The nucleons inside the deuterium nucleus are held together by residual QCD effects (the complicated mess of quark-antiquark pairs and gluons), but they themselves are colour-neutral bound states (you can take each of them out of the nucleus and they would still be bound states).    From Wordnik.com.  [physicsworld.com: all content] Reference

A research team led by MIT, CERN and the KFKI Research Institute for Particle and Nuclear Physics in Budapest, Hungary have released a report detailing findings that the collisions are producing an "unexpectedly" high number of particles called mesons, subatomic particles composed of one quark and one antiquark.    From Wordnik.com.  [Medlogs - Recent stories] Reference

Language Log in 2005, he commented: "Given the expected resistance of editors to 'could care less', the fact that it appears in print 11 years after the first citation for 'couldn't care less' suggests to me that the two expressions probably arose at essentially the same time, like quark-antiquark pairs in a high-energy collision.".    From Wordnik.com.  [Visual Thesaurus : Online Edition] Reference

B (10890), a tetraquark meson formed of an up flavour "diquark" (quark-antiquark pair) and a bottom flavour diquark, is very close in mass to Y (5S).    From Wordnik.com.  [physicsworld.com: all content] Reference

The previous week, the D0 experiment at Fermilab’s Tevatron (the main proton-antiproton collider) released new results on the oscillations of a different kind of particle, the Bs meson (a composite of a strange quark and a bottom antiquark), as reported in this paper.    From Wordnik.com.  [Particle physics marches on] Reference

"In particle physics, mesons are subatomic particles composed of one quark and one antiquark.    From Wordnik.com.  [Original Signal - Transmitting Gadgets] Reference