Search

If dark matter couples predominantly to the axial-vector currents with heavyquarks, the leading contribution to dark-matter scattering on nuclei is eitherdue to one-loop weak corrections or due to the heavy-quark axial charges of thenucleons. We calculate the effects of Higgs and weak gauge-boson exchanges fordark matter coupling to heavy-quark axial-vector currents in an effectivetheory below the weak scale. By explicit computation, we show that theleading-logarithmic QCD corrections are important, and thus resum them to allorders using the renormalization group.

Abstract We discuss how LHC di-muon data collected to study B q → μμ can be used to constrain light particles with flavour-violating couplings to b-quarks. Focussing on the case of a flavoured QCD axion, a, we compute the decay rates for B q → μμa and the SM background process B q → μμγ near the kinematic endpoint. These rates depend on non-perturbative B q → γ (*) form factors with on- or off-shell photons. The off-shell form factors — relevant for generic searches for beyond-the-SM particles — are discussed in full generality and computed with QCD sum rules for the first time. This includes an extension to the low-lying resonance region using a multiple subtracted dispersion relation. With these results, we analyse available LHCb data to obtain the sensitivity on B q → μμa at present and future runs. We find that the full LHCb dataset alone will allow to probe axion-coupling scales of the order of 106 GeV for both b → d and b → s transitions. As a spin-off application of the off-shell form factors we further analyse the case of light, Beyond the Standard Model, vectors.

Abstract Electric dipole moments are sensitive probes of new phases in the Higgs Yukawa couplings. We calculate the complete two-loop QCD anomalous dimension matrix for the mixing of CP-odd scalar and tensor operators and apply our results for a phenomenological study of CP violation in the bottom and charm Yukawa couplings. We find large shifts of the induced Wilson coefficients at next-to-leading-logarithmic order. Using the experimental bound on the electric dipole moments of the neutron and mercury, we update the constraints on CP-violating phases in the bottom and charm quark Yukawas.

Abstract LHCb has reported hints of lepton-flavor universality violation in the rare decays B → K (*) ℓ + ℓ −, both in high- and low-q 2 bins. Although the high-q 2 hint may be explained by new short-ranged interactions, the low-q 2 one cannot. We thus explore the possibility that the latter is explained by a new light resonance. We find that LHCb’s central value of R K * $$ {R}_{K^{*}} $$ in the low-q 2 bin is achievable in a restricted parameter space of new-physics scenarios in which the new, light resonance decays preferentially to electrons and has a mass within approximately 10 MeV of the di-muon threshold. Interestingly, such an explanation can have a kinematic origin and does not require a source of lepton-flavor universality violation. A model-independent prediction is a narrow peak in the differential B → K * e + e − rate close to the di-muon threshold. If such a peak is observed, other observables, such as the differential B → Ke + e − rate and R K , may be employed to distinguish between models. However, if a low-mass resonance is not observed and the low-q 2 anomaly increases in significance, then the case for an experimental origin of the lepton-flavor universality violating anomalies would be strengthened. To further explore this, we also point out that, in analogy to J/ψ decays, e + e − and μ + μ − decays of ϕ mesons can be used as a cross check of lepton-flavor universality by LHCb with 5 fb−1 of integrated luminosity.

Abstract If dark matter couples predominantly to the axial-vector currents with heavy quarks, the leading contribution to dark-matter scattering on nuclei is either due to one-loop weak corrections or due to the heavy-quark axial charges of the nucleons. We calculate the effects of Higgs and weak gauge-boson exchanges for dark matter coupling to heavy-quark axial-vector currents in an effective theory below the weak scale. By explicit computation, we show that the leading-logarithmic QCD corrections are important, and thus resum them to all orders using the renormalization group.