Abstract: Very light axions are a generic prediction of string compactifications. If cosmic strings associated with these axions were produced in the early universe, they quickly approach a so-called scaling solution, such that strings persist in the sky today. I will present some remarkable signals of such strings coupled to photons. In this string background, there is a new Berry … Read More
New dark vector bosons that couple very feebly to regular matter can be produced in the early universe and decay after the onset of Big Bang Nucleosynthesis (BBN) or the formation of the cosmic microwave background (CMB) at recombination. The energy injected by such decays can modify the light element abundances or modify the power and frequency spectra of the … Read More
Abstract: The asymmetry between matter and antimatter is one of the big outstanding questions of particle physics and cosmology. In this talk, I will argue that electroweak baryogenesis is an interesting mechanism to generate the baryon asymmetry. The new physics needed for electroweak baryogenesis come into play at a relatively low scale and can thus be tested in experiment. I … Read More
The talk will cover recent work on using effective field theories (SMEFT and HEFT) to constrain the electroweak symmetry breaking sector. It will also discuss recently discovered results on holomorphy in general (non-SUSY) QFT.
The search for new, sub-GeV particles has become the center of much interest. In a first part, I will consider light dark states that share a direct coupling with the photon through higher dimensional operators (âphoton portalâ). The prospects of detecting such states at the intensity frontier will be confronted with low-energy precision tests as well as with cosmological and … Read More
Abstract: In this talk I will present new constraints on U(1)LμâLÏ symmetry. In pulsar binaries, such U(1)LμâLÏ vectors induce an anomalously fast decay of the orbital period through the emission of dipole radiation. I’ll show the range of different pulsar binaries, finding the most powerful constraints for vector masses below O(10â18eV). For merging binaries the presence of muons in neutron … Read More
https://lbnl.zoom.us/j/215429094
Functional methods, in particular efficient reorganization of the one-loop effective action, have in recent years made a reappearance in simplifying the problem of computing matching and running effects in Lorentz-invariant EFTs such as the SMEFT. This has lead to the appearance of universal one-loop effective actions, where many such effects are now known in closed form for arbitrary field-content. Similar … Read More
Abstract: I will discuss a production scenario for QCD axion dark matter where the Peccei-Quinn phase transition occurs at a temperature far below the symmetry breaking scale. Both early cosmic string network dynamics and parametric resonance contribute to the axion population. The observed dark matter abundance is reproduced even if the decay constant is much lower than 10^11 GeV. I … Read More
Abstract: Soft Collinear Effective Theory (SCET) can be made compatible with supersymmetry, and such a theory can be conveniently formulated in “Collinear Superspace”. In this talk I will introduce a new set of effective field theory rules for constructing Lagrangians in collinear superspace. This new formalism represents a general way to derive on-shell superspace Lagrangians directly from the symmetries of … Read More