C3b: New Physics models for flavour observables

Project C3b addresses flavour physics in theories beyond the Standard Model (BSM). We study hints for BSM physics in precision data on rare processes, explore the phenomenology of hypothetical light new particles (such as axion-like particles) in modern flavour experiments, and construct BSM models with quark-lepton unification, horizontal symme-tries, or additional Higgs fields.

1. Multi-Higgs doublet models with heavy Higgses
   • devise extended Higgs sectors to alleviate flavour anomalies
   • improve $B_c$ lifetime constraint
   • predict branching fraction for $h\to \tau \mu$
2. Multi-Higgs doublet models with a light neutral Higgs
   • study light neutral pseudoscalar $\phi$ from broken flavour symmetries
   • explore $B\to D^{(*)} \ell \nu \phi $ events in $B\to D^{(*)} \tau[\to\ell\nu\bar\nu] \nu$ data sample
3. $\mathbf{b\to s \ell^+\ell^-}$ and the flavour puzzle
   • construct models of radiatively generated muon and electron masses containing large LFUV parameters needed to explain $R_{K^{(*)}}$
   • $Z^\prime$ from gauged flavour symmetries
4. Flavour and supersymmetry
   • study hierarchical squark masses enhancing FCNC transitions
   • construct a supersymmetric SU(2)$_L\times$SU(2)$_R$ model
5. Pati-Salam and $\mathbf{E_6}$-inspired models
   • study scalar leptoquarks of Pati-Salam Higgs sector
   • construct $\mathbf{E_6}$-inspired models with $Z^\prime$ and vectorlike fermions