title Search for pair production of vector-like quarks in the math altimg=”si1.gif” overflow=”scroll” mi mathvariant=”normal”b/mi mi mathvariant=”normal”W/mi mover accent=”true” mrow mi mathvariant=”normal”b/mi /mrow mo‾/mo /mover mi mathvariant=”normal”W/mi /math channel from proton–proton collisions at math altimg=”si100.gif” overflow=”scroll” msqrt mrow mis/mi /mrow /msqrt mo=/mo mn13/mn mspace width=”0.2em”/ mtextTeV/mtext /math/title