Two Higgs Doublets, a 4th Generation and a 125 GeV Higgs: A Review

Figure 5

Allowed area in the 𝑚_𝐻⁺−tan𝛽 in the 4G2HDMI, subject to the 𝑅_𝑏 measurement (within 2𝜎), for 𝑚_𝑡′=500 GeV,  𝑚_𝑏′=450 GeV, 𝜃₃₄=0.2, and  𝜖_𝑏=𝑚_𝑏/𝑚_𝑏′ and for three values of the 𝑡−𝑡^′ mixing parameter: 𝜖_𝑡=𝜖_𝑏∼0.01 (a),  𝜖_𝑡=𝑚_𝑡/𝑚_𝑡′∼0.35 (b), and 𝜖_𝑡=1 (c). Figure taken from [61].

(a)

(b)

(c)