Publications

The Two-Higgs Doublet Model (2HDM) is a well understood alternative to the Standard Model of particle physics. If the new particles included in the 2HDM are at an energy scale much greater than the weak scale, the theory can be matched to the Standard Model Effective Field Theory (SMEFT). We compute for the first time the complete one-loop matching at dimension-6. We compare its numerical impact with that of tree-level matching at dimension-8 by performing a global fit to single Higgs and precision electroweak measurements, and we emphasize the importance of comparing one-loop SMEFT results with corresponding one-loop results in the full 2HDM model. In the SMEFT, we consider the relative importance of both one-loop matching and the inclusion of renormalization group evolution. Our results demonstrate the necessity of studying the impact of various expansions to quantify the uncertainties of the SMEFT matching.

Massless chiral excitations can arise from the interactions between a fermion and an axion string, propagating along the string and allowing it to superconduct. The properties of these excitations, or zero modes, dictate how the string interacts with light and can thus have important phenomenological consequences. In this paper, we add a nowhere-vanishing Dirac mass for the fermion in the usual model of axion electrodynamics. We find that the zero modes exhibit an interesting phase structure in which they delocalize from the string’s core as the mass increases, up until a critical value past which they disappear. We study this structure from an analytic perspective, with explicit numerical solutions, and via anomaly inflow arguments. Finally, we derive the two-dimensional effective theory of the zero mode and its interactions with the four-dimensional gauge field and show how this effective theory breaks down as the zero modes delocalize.

When the Froggatt-Nielsen mechanism is used to explain the Standard Model flavor hierarchy, new physics couplings are also determined by the horizontal symmetry. However, additional symmetries or dynamics in the UV can sometimes lead to a departure from this naïve scaling for the new physics couplings. We show that an effective way to keep track of these changes is by using the new spurions of the $\textrm{U}(3)^5$ global flavor symmetry, where we parameterize extra suppression or enhancement factors, referred to as wrinkles, using the same power counting parameter as in the original Froggatt-Nielsen model. As a concrete realization, we consider two flavor spurions of the S1 leptoquark, and demonstrate that wrinkles can be used to make an enhanced value of $\textrm{BR}(B^+\to K^+\nu\bar{\nu})$ consistent with other flavor observables. We also present example UV models that realize wrinkles, and comment on choosing consistent charges in ordinary Froggatt-Nielsen models without the typical monotonicity condition.

We discuss the phenomenological consequences of a gauged CP symmetry in the context of the Nelson–Barr solution to the strong CP problem. Exactly stable domain walls form when CP is spontaneously broken, and must be inflated away to recover a viable cosmology. We discuss the severe consequences for models of inflation and baryogenesis, and the tension with the “Nelson–Barr Quality Problem”, which sets an upper bound on the scale at which CP is broken. Finally, we present an explicit chiral model in which the bound on the CP-breaking scale is ameliorated.

We consider the compatibility of the recent CDF measurement of the W mass in an electroweak global fit, with new physics parameterized by the oblique parameters, S, T and U. We show that the large value can be explained by introducing a new SU(2) triplet scalar, the “swino”.

We explore complementary signatures of lepton flavor violation at high-energy muon colliders, precision lepton-flavor experiments such as Mu2e and Mu3e, and EDM experiments in a supersymmetric scenario with flavor-mixed sleptons.

We examine the importance of one-loop matching of the singlet onto the SM Effective Field Theory, quantifying the effects via a global fit to Higgs measurements at the LHC and Electroweak Precision observables.

We examine a deep relationship between enhanced couplings of the Higgs to light quarks and the di-Higgs production process at the LHC.

We examine SMEFT fits for common extensions of the SM to understand how global fits should be interpreted in the context of new physics.

We extend our analysis of NLO corrections in the SMEFT on $WW$ and $WZ$ to include the $WH$ and $ZH$ processes.

We show that the observed events at the KOTO experiment can be explained by minimal models of light new physics.

We show that NLO effects in the SMEFT have dramatic effects on the observed limits obtained from $WW$ and $WZ$ production data.

We show that Higgses with large couplings to light quarks lead to interesting signals in dijets and enhanced Higgs Yukawas, and are motivated by Spontaneous Flavor Violation.

We analyze WH production using the MadMiner machine learning tool and quantify the information in kinematic phase space.

A study of the capabilities of a potential 27 TeV HE-LHC upgrade in measuring the Higgs self-coupling via di-Higgs production.

A whitepaper detailing opportunities in Higgs physics at the LHC in the future.

A search for instability of nucleons bound in Xe-136 nuclei is reported with 223 kg yr exposure of Xe136 in the EXO-200 experiment. Lifetime limits of 3.3 x 10^23 and 1.9 x 10^23 yr are established for nucleon decay to Sb133 and Te133, respectively. These are the most stringent to date, exceeding the prior decay limits by a factor of 9 and 7, respectively.

We discuss flavor-aligned theories, which avoid bounds from Flavor-Changing Neutral Currents, and introduce the Spontaneous Flavor Violation Ansatz.

A search for Lorentz- and CPT-violating signals in the double beta decay spectrum of 136-Xe has been performed using an exposure of 100 kg yr with the EXO-200 detector. No significant evidence of the spectral modification due to isotropic Lorentz-violation was found, and a two-sided limit of -2.65 x 10^5 GeV < a^(3)_of < 7.60 x 10^-6 GeV (90% C.L.) is placed on the relevant coefficient within the Standard-Model Extension (SME). This is the first experimental study of the effect of the SME-defined oscillation-free and momentum-independent neutrino coupling operator on the double beta decay process.