Answer: gluon

AnswerCrossword Clue
GLUONQuark binder, in theory
GLUONHypothetical particle
GLUONQuark-binding particle
GLUONParticle emitted by a quark
GLUONMassless subatomic particle believed to bind quarks together
GLUONSubatomic particle thought to bind quarks together
GLUONTheoretical massless particle
GLUONBinding elementary particle
GLUONQuark binder
gluona hypothetical binding particle
gluona hypothetical neutral massless particle held to bind together quarks to form hadrons
gluonunobserved massless particle with spin 1 that is believed to transmit the strong force between quarks, binding them together into baryons and mesons