noun
Physics term for a subatomic particle composed of a quark and an antiquark.
中間子はクォークと反クォークからなる素粒子です。
A meson is an elementary particle made of a quark and an antiquark.
素粒子 is a broader term for elementary particles, while 中間子 specifically refers to mesons.
From 中間 (middle) + 子 (particle), a calque of English 'meson', which derives from Greek 'mesos' (middle) because its mass is between that of an electron and a proton.