LHC Signatures of Vector-Like Quarks

Table 1

Allowed representations for VLQs, with quantum numbers under 𝑆𝑈(2)_𝐿 and 𝑈(1)_𝑌 and Yukawa mixing terms in the Lagrangian. Depending on the chosen representation, the Higgs boson may be 𝐻 or 𝐻^𝑐; therefore it has been noted as 𝐻^(𝑐) when necessary. The gauge invariant mass term common to all representations is a peculiar feature of VLQs.

	SM quarks			Singlets		Doublets			Triplets
	(^𝑢𝑑)	(^𝑐𝑠)	𝑡𝑏	(𝑈)	(𝐷)	𝑋𝑈	𝑈𝐷	𝐷𝑌	𝑋𝑈𝐷	𝑈𝐷𝑌
𝑆𝑈(2)𝐿		𝑞𝐿𝑞=2𝑅=1		1			2		3
𝑈(1)𝑌		𝑞𝐿𝑢=1/6𝑅𝑑=2/3𝑅=−1/3		2/3	−1/3	7/6	1/6	−5/6	2/3	−1/3
ℒ𝑌		−𝑦^𝑖𝑢𝑞^𝑖𝐿𝐻^𝑐𝑢^𝑖𝑅−𝑦^𝑖𝑑𝑞^𝑖𝐿𝑉^𝑖,𝑗𝐶𝐾𝑀𝐻𝑑^𝑗𝑅		−𝜆^𝑖𝑢𝑞^𝑖𝐿𝐻^𝑐𝑈𝑅−𝜆^𝑖𝑑𝑞^𝑖𝐿𝐻𝐷𝑅			−𝜆^𝑖𝑢𝜓𝐿𝐻^(𝑐)𝑢^𝑖𝑅−𝜆^𝑖𝑑𝜓𝐿𝐻^(𝑐)𝑑^𝑖𝑅		−𝜆𝑖𝑞^𝑖𝐿𝜏^𝑎𝐻^(𝑐)𝜓^𝑎𝑅
ℒ𝑚		Not allowed					−𝑀𝜓𝜓