CERN-PH-TH-2015-158 TTP15-023 FLAVOUR(267104)-ERC-104 Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1

The Littlest Higgs Model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. The latter originate in the interactions of ordinary quarks and leptons with heavy mirror quarks and leptons that are mediated by new heavy gauge bosons. Also a heavy fermionic top partner is present in this model which communicates with the SM fermions by means of standard W ± and Z0 gauge bosons. We present a new analysis of quark observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare K and B decays are still allowed to depart from their SM values. This includes K+ → pi+νν̄, KL → pi0νν̄, KL → µ+µ−, ε′/ε, B → Xsγ, Bs,d → µ+µ−, B → K(∗)`+`−, B → K(∗)νν̄. Taking into account the constraints from ∆F = 2 processes, significant departures from the SM predictions for K+ → pi+νν ̄ and KL → pi0νν ̄ are possible while the effects in B decays are much smaller. I