It is common practice to explain deviations between data and Standard-Model predictions by postulating new particles at the TeV scale ad-hoc. This approach becomes much more convincing, if one successfully embeds the postulated particles into a UV completion which addresses other conceptual or phenomenological shortcomings of the SM. We present a study of an SO(10) grand unified theory which...
We illustrate the potential of a future high-intensity $e^+e^-$ collider operating at the $Z$ pole to probe extensions of the Standard Model through precise measurements of flavor-changing processes, both within the framework of effective field theories and in simplified models motivated by current BB-physics anomalies. Our focus is on selected flavor-physics projections at FCC-ee and on a...
The Higgs self coupling is one of the last not precisely measured couplings in the SM with a current precision of $\mathcal{O}(100\%)$. Within the SMEFT, the BSM contribution to the trilinear self coupling of the Higgs is the operator $\mathcal{O}_H$, which enters at NLO in the $e^+e^- \to ZH$ cross section, providing an interesting probe for the self-coupling at future lepton colliders....
Since the discovery of the Higgs boson, no clear footprints of New Physics (NP) have been observed at the LHC. This absence suggests a separation between the scale of NP and the electroweak scale. In this scenario, Effective Field Theories (EFTs) provide a model-independent framework to analyze LHC data and search for indirect signs of beyond-the-Standard-Model effects. In particular, diboson...
In this talk, we revisit the one-loop renormalization group equations (RGEs) among nondegenerate seesaw scales, i.e., threshold effects in the canonical seesaw mechanism, which have been obtained for more than two decades. Different from the previous work only focusing on the Weinberg operator, we derive the complete one-loop RGEs of all three dimension-five operators in the Standard Model...
The first observation of $\mathcal{B}\left(B^+\rightarrow K^+\nu\nu\right)$ by the Belle II experiment lies almost $3\sigma$ away from the Standard Model expectation. In this work we study this result in the SMEFT, extended by a light right-handed neutrino. We explore the correlations between the measured decay rate and other observables, such as $\mathcal{B}\left(B\rightarrow...
Lifetimes of mesons containing a heavy quark can be described by an operator product expansion involving four-quark operators. To determine these lifetimes, both perturbative Wilson coefficients as well as non-perturbative hadronic matrix elements are needed. The gradient-flow formalism provides a way for calculating the latter in lattice gauge theory. Suitable perturbative matching...
In this talk, we discuss the computation of form factors for decays of heavy into light quarks at third order in QCD for various currents. We describe the different steps of the calculation and use the results to compute the hard matching coefficients in Soft-Collinear Effective Theory for all currents. Further, we extract the hard function in $\bar B \to X_s \gamma$ to three loops and study...
The calculation of the branching ratio for the inclusive decay $\bar B \to X_s \gamma$ has been an active field of research for multiple decades, yielding results that work very well as a
standard candle of the Standard Model of Particle Physics (SM). In this work, we calculate the remaining pieces for the branching ratio of the four-body decay of a b quark into an s quark, a photon $\gamma$...
Rare decays like B→Ka offer a sensitive window to search for axion-like particles (ALPs), especially for heavier ALPs with masses in the range of MeV to a few GeV. We present a detailed study of these decays within the framework of weak effective theory. We show that to consistently include ALPs in this framework, one must extend the usual set of effective operators by introducing new ones. We...
Axions that couple to nuclear spins via the axial nuclear moment interaction can be both produced and detected using NMR techniques. The gradient of the radiated axion field is set by the size of the spin-polarized source, which can greatly exceed that of ambient axion dark matter. This sourced axion field can be resonantly detected using NMR and measured with sensitive magnetometers. In this...
