In recent years, experiments revealed intriguing hints for new physics (NP) in semi-leptonic B decays. Both in charged current processes, involving b → cτ ν transitions, and in the neutral currents b → s + − , a preference for NP compared to the standard model (SM) of more that 3σ and 5σ was found, respectively. In addition, there is the long-standing tension between the theory prediction and the measurement of the anomalous magnetic moment (AMM) of the muon (a µ ) of more than 3σ. Since all these observables are related to the violation of lepton flavor universality (LFU), a common NP explanation seems not only plausible but is even desirable. In this context, leptoquarks (LQs) are especially promising since they give tree-level effects in semi-leptonic B decays, but only loop-suppressed effects in other flavor observables that agree well with their SM predictions. Furthermore, LQs can lead to a m t /m µ enhanced effect in a µ , allowing for an explanation even with (multi) TeV particles. However, a single scalar LQ representation cannot provide a common solution to all three anomalies. In this article we therefore consider a model in which we combine two scalar LQs: the SU(2) L singlet and the SU(2) L triplet. Within this model we compute all relevant 1-loop effects and perform a comprehensive phenomenological analysis, pointing out various interesting correlations among the observables. Furthermore, we identify benchmark points which are in fact able to explain all three anomalies (b → cτ ν, b → s + − and a µ ), without violating bounds from other observables, and study their predictions for future measurements.

In recent years experiments revealed intriguing hints for new physics (NP) in B decays involving b → cτ ν and b → s + − transitions at the 4 σ and 5 σ level, respectively. In addition, there are slight disagreements in b → uτ ν and b → dµ + µ − observables. While not significant on their own, they point in the same direction. Furthermore, Vus extracted from τ decays shows a slight tension (≈ 2.5 σ) with its value determined from CKM unitarity and an analysis of BELLE data found an excess in B d → τ + τ − . Concerning NP explanations, the vector leptoquark SU (2) singlet is of special interest since it is the only single particle extension of the Standard Model which can (in principle) address all the anomalies described above. For this purpose, large couplings to τ leptons are necessary and loop effects, which we calculate herein, become important. Including them in our phenomenological analysis, we find that neither the tension in Vus nor the excess in B d → τ + τ − can be fully explained without violating bounds from K → πνν. However, one can account for b → cτ ν and b → uτ ν data finding intriguing correlations with Bq → τ + τ − and K → πνν. Furthermore, the explanation of b → cτ ν predicts a positive shift in C7 and a negative one in C9, being nicely in agreement with the global fit to b → s + − data. Finally, we point out that one can fully account for b → cτ ν and b → s + − without violating bounds from τ → φµ, Υ → τ µ or b → sτ µ processes.of B → πµ + µ − [12] slightly differs from the theory expectation. Even though this is not significant on its own, the central value is very well in agreement with the expectation from b → s + − under the assumption of a V td /V ts -like scaling of the NP effect [71]. In other words, an effect of the same order and sign as in b → s + − , relative to the SM, is preferred. Furthermore, an (unpublished) analysis of BELLE data found an excess inThe ratioswhich measure LFU violation in the charged current by comparing τ modes with light leptons ( = e, µ), differ in combination from their SM predictions by ≈ 4 σ [14]. Also, the ratio R(J/ψ) = Br[B c → J/ψτ ν] Br[B c → J/ψµν][15] exceeds the SM prediction in agreement with the expectations from R(D ( * ) ) [16,17]. Concerning b → uτ ν transitions, the theory prediction for B → τ ν crucially depends on V ub . While previous arXiv:1807.02068v2 [hep-ph]

Leptoquarks are hypothetical new particles, which couple quarks directly to leptons. They experienced a renaissance in recent years as they are prime candidates to explain the so-called flavor anomalies, i.e. the deviations between the Standard Model predictions and measurements in b → sℓ+ℓ− and b → cτν processes and in the anomalous magnetic moment of the muon. At the one-loop level these particles unavoidably generate effects in the purely leptonic processes like Z → ℓ+ℓ−, Z →$$ v\overline{v} $$ v v ¯ , W → ℓν and h → ℓ+ℓ− and can even generate non-zero rates for lepton flavor violating processes such as ℓ → ℓ′γ, Z → ℓ+ℓ′−, h → ℓ+ℓ′− and ℓ → 3ℓ′. In this article we calculate these processes for all five representations of scalar Leptoquarks. We include their most general interaction terms with the Standard Model Higgs boson, which leads to Leptoquark mixing after the former acquires a vacuum expectation value. In our phenomenological analysis we investigate the effects in modified lepton couplings to electroweak gauge bosons, we study the correlations of the anomalous magnetic moment of the muon with h → μ+μ− and Z → μ+μ− as well as the interplay between different lepton flavor violating decays.

In this article we investigate the correlations between tauonic B meson decays (e.g. B → τ ν, B → D ( * ) τ ν, B → πτ ν) and electric dipole moments (EDMs), in particular the one of the neutron, in the context of the S1 scalar leptoquark. We perform the matching of this model on the effective field theory taking into account the leading renormalization group effect for the relevant observables. We find that one can explain the hints for new physics in b → cτ ν transitions without violating bounds from other observables. Even more interesting, it can also give sizable effects in B → τ ν, to be tested at BELLE II, which are correlated to (chromo) electric dipole operators receiving mτ /mu enhanced contributions. Therefore, given a deviation from the Standard Model (SM) expectations in B → τ ν, this model predicts a sizable neutron EDM. In fact, even if new physics has CP conserving real couplings, the CKM matrix induces a complex phase and already a 10% change of the B → τ ν branching ratio (with respect to the SM) will lead to an effect observable with the n2EDM experiment at PSI.

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