Light charged Higgs boson scenario in 3HDMs
  The measurement of the $B\to X_s\gamma$ process gives important constraints on physics related to charged Higgs bosons ($H^\pm$). In 2-Higgs Doublet Models (2HDMs) with a softly-broken $Z_2$ symmetry, a light $H^\pm$ scenario, in which $H^\pm$ can be produced via the top decay, is possible in two of four types of Yukawa interactions (the so-called Type-I and Type-X). In these types of 2HDMs, the $H^\pm \to \tau^\pm \nu$ decay mode is dominant in wide regions of the parameter space. In this report, we discuss the other possibility of a light charged Higgs boson scenario in 3-Higgs-Doublet Models (3HDMs) based on the results obtained in Ref. [1]. We show that charged Higgs bosons can mainly decay into $cb$ without contradiction with the $B\to X_s\gamma$ data and the direct searches for charged Higgs bosons at the LHC, and this scenario cannot be realized in the 2HDMs. 
A. G. Akeroyd, Stefano Moretti, Kei Yagyu, Emine Yildirim
hep-ph