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