Higgs mediated Flavour Violation in 2HDMs and the MSSM -- An Overview

In these proceedings we review the flavour phenomenology of two-Higgs-doublet models (2HDMs) and connect the results to the decoupling limit of the MSSM. We first study the impact of FCNC constraints on the allowed parameter space of the 2HDM and examine how recent deviations from the SM expectations in tauonic $B$ decays (observed by BABAR) can be explained in a 2HDM with generic flavour structure (of type III) with sizable flavour violation in the up-sector. Afterwards, we discusses the matching of the MSSM on the 2HDM of type III. Here we focus on the two-loop SQCD corrections to the Higgs-quark-quark couplings.Comment: Proceedings for "Les Rencontres de Physique de la Vallee d'Aoste", 8 pages, 4 figure

Chiral Enhancement in the MSSM -- An Overview

In this article I review the origin and the effects of chirally enhanced loop-corrections in the MSSM based on Refs. [1-3]. Chiral enhancement is related to fermion-Higgs couplings (or self-energies when the Higgs field is replaced by its vev). I describe the resummation of these chirally-enhanced corrections to all orders in perturbation theory and the calculation of the effective fermion-Higgs and gaugino(higgsino)-fermion vertices. As an application a model with radiative flavor-violation is discussed which can solve the SUSY-CP and the SUSY-flavor problem while it is still capable of explaining the observed deviation from the SM in the Bs mixing phase.Comment: Talk given at 25th Les Rencontres de Physique de La Vallee d'Aoste, La Thuile, Aosta Valley, Italy, 27 Feb - 5 Mar 201

Flavor violation in the MSSM and implications for top and squark searches at colliders

In this article I review some connections between flavor physics and collider physics. The first part discusses the effect of right-handed charged currents on the determination of the CKM elements V_ub. It is shown that such an effective right-handed W-coupling can be generated in the MSSM which would lead to a sizable enhancement of single-top production at the LHC. The second part of this article focuses on the constraints on the mass splitting between left-handed squarks from Kaon and D mixing. Such a mass splitting has interesting consequences for squark decay chains at colliders.Comment: 11 pages, 4 figures. Presented at Linear Collider 2011: Understanding QCD at Linear Colliders in searching for old and new physics, 12-16 September 2011, ECT*, Trento, Ital

Tauonic B decays in 2HDMs and the MSSM in the decoupling limit

In these proceedings we review two aspects of 2HDMs with generic Yukawa structures. The first part considers how recent deviations from the SM expectations in tauonic B decays (observed by BABAR) can be explained in a 2HDM of type III with sizable flavour violation in the up-sector. The second part discusses the matching of the MSSM on the 2HDM of type III. Here we focus on the recently calculated two-loop SQCD corrections to the Higgs-quark-quark couplings.Comment: 6 pages, 3 figures, proceedings of: Prospects for Charged Higgs Discovery at Colliders - Charged 201

New Physics in BB decays

While the LHC did not observe direct evidence for physics beyond the standard model, indirect hints for new physics were uncovered in the flavour sector in the decays $B\to K^*\mu^+\mu^-$, $B\to K\mu^+\mu^-/B\to Ke^+e^-$, $B_s\to\phi\mu^+\mu^-$, $B\to D^{(*)}\tau\nu$ and $h\to\tau^\pm\mu^\mp$. Each observable deviates from the SM predictions at the $2-3\,\sigma$ level only, but combining all $b\to s\mu^+\mu^-$ data via a global fit, one finds $4-5\,\sigma$ difference for NP compared to the SM and combining $B\to D^{*}\tau\nu$ with $B\to D\tau\nu$ one obtains $3.9\,\sigma$. While $B\to D^{(*)}\tau\nu$ and $h\to\tau\mu$ can be naturally explained by an extended Higgs sector, the $b\to s\mu^+\mu^-$ anomalies point at a $Z'$ gauge boson. However, it is also possible to explain $B\to D^{(*)}\tau\nu$ and $b\to s\mu^+\mu^-$ simultaneously with leptoquarks while their effect in $h\to\tau^\pm\mu^\mp$ is far too small to account for current data. Combining a 2HDM with a gauged $L_\mu-L_\tau$ symmetry allows for explaining the $b\to s\mu^+\mu^-$ anomalies in combination with $h\to\tau^\pm\mu^\mp$, predicting interesting correlations with $\tau\to3\mu$. In the light of these deviations from the SM we also discuss the possibilities of observing lepton flavour violating $B$ decays (e.g. $B\to K^{(*)}\tau^\pm\mu^\mp$ and $B_s\to\tau^\pm\mu^\mp$).Comment: 9 pages, 6 figures, proceedings for "Flavour changing and conserving processes" 2015, references adde

Challenges for New Physics in the Flavour Sector

In these proceedings I present a personal perspective of the challenges for new physics (NP) searches in the flavour sector. Since the CKM mechanism of flavour violation has been established to a very high precision, we know that physics beyond the Standard Model can only contribute sub-dominantly. Therefore, any realistic model of physics beyond the Standard Model (SM) must respect the stringent constrains from flavour observables like $b\to s \gamma$, $B_s\to\mu^+\mu^-$, $\Delta F=2$ processes etc., in a first step. In a second step, it is interesting to ask the question if some deviations from the SM predictions (like the anomalous magnetic moment of the muon or recently observed discrepancies in tauonic $B$ decays or $B\to K^*\mu^+\mu^-$) can be explained by a model of NP without violating bounds from other observables.Comment: Presented at the 2014 Flavour Physics and CP Violation (FPCP-2014), Marseille, France, May 26-30 2014, 27 pages, 6 figures, references adde