also: ボトムクオーク
noun
bottom quark
A type of elementary particle in the Standard Model of particle physics.
ボトムクォークは第三世代のクォークに分類される。
The bottom quark is classified as a third-generation quark.
The top quark is the heavier partner of the bottom quark in the third generation.
The charm quark is a second-generation quark, lighter than the bottom quark.
The strange quark is a second-generation quark, also lighter than the bottom quark.
The up quark is a first-generation quark, much lighter than the bottom quark.
The down quark is a first-generation quark, much lighter than the bottom quark.
From English 'bottom quark'. The term 'bottom' was chosen as a counterpart to 'top' quark, reflecting their pairing in the third generation of quarks.