arXiv subjects

Nathaniel Sherrill

Publications and source records attributed to Nathaniel Sherrill.

8 recordsLinked to original sources

arXiv2026

High Precision Fundamental Physics Experiments at JLab with Spin-transparent Storage Rings of Low-energy Polarized Electron Beams

A breakthrough in fundamental physics experiments measuring particle spin precession may happen if spin-transparent storage rings become adopted tools for such experiments. We present a new design of highly specialized table-sized storage rings, which use low-energy polarized electron beams and Mott polarimetry. Based on the spin transparency ansatz, the spin precession stemming from the magnetic dipole moment is canceled at any beam energy after an electron's turn along the periodic orbit in the ring. Meanwhile, a spin precession induced by the fundamental physics of interest, e.g., the electron's permanent electric dipole moment (EDM) and/or ultralight-dark-matter-mediated forces such as axions, will accumulate. However, capitalizing on such types of rings is not only desirable for measurements of EDMs and axion searches relevant to $CP$ violation and matter-antimatter asymmetry in the Universe, but may also find very promising applications in quantum computing.

nucl-ex↗

arXiv2026

Probing Lorentz invariance via diphoton decays of the Higgs boson

The prospects for observing small departures from Lorentz invariance are studied using effective interactions of the Higgs boson with photons. A single operator of mass-dimension five suffices to describe all leading signatures of Lorentz violation in the diphoton decay channel. Comparison of the theoretical modified decay rates with observed signal strengths measured by the ATLAS and CMS Collaborations at the Large Hadron Collider indicates an estimated attainable sensitivity to the corresponding coefficients for Lorentz violation of order $10^{-4}$ GeV$^{-1}$.

hep-ph↗

arXiv2025

Apparent Lorentz violation from disformally coupled ultralight dark matter

We study the impact of general disformal metric transformations on fermions, which shift the gravitational metric by an additional rank-2 tensor. This tensor can in principle be constructed from scalar-field gradients, vector fields, or field-strength contractions. We show this transformation results in the conventional Dirac action being modified by additional kinetic and axial-current couplings that are quadratic in the shifted field. When the field sourcing the metric shift takes on a non-trivial background value, apparent Lorentz-violating effects can result, which we identify as terms in an effective field theory. Assuming the well-motivated cases of scalar and vector ultralight dark matter, we demonstrate that experimental tests of rotation and boost violation imply constraints on the additional kinetic coupling. Even under conservative assumptions, the constraints for vector ultralight dark matter are extremely stringent.

hep-ph↗

arXiv2024

Signals of nonrenormalizable Lorentz and CPT violation at the LHC

We examine nonrenormalizable Lorentz- and CPT-violating effective operators applied to the quark sector of the Standard Model. Using Drell-Yan events collected by the ATLAS and CMS Collaborations, several constraints are extracted from time-independent modifications of the cross section on the $Z$-boson pole. The sensitivity to time-dependent modifications are also estimated by simulating a sidereal-time analysis. Our results suggest a dedicated search can improve on constraints from deep inelastic scattering by up to three orders in magnitude.

hep-ph↗

arXiv2024

Probing Grand Unification with Quantum Sensors

We discuss how grand unification can be probed with experiments at low energies using quantum sensors. Specifically, we show that scalar multiplets coupled to the gauge sector of a grand unified theory provide a mechanism for a time-varying unified coupling which has low-energy consequences which can be probed with quantum sensors. We then assume that the multiplets represent ultra light dark matter. Constraints on ultra light dark matter couplings to regular matter are extracted using atomic clock comparisons, pulsar timing arrays (NANOGrav) and MICROSCOPE.

hep-ph↗

arXiv2023

Analysis of atomic-clock data to constrain variations of fundamental constants

We present a new framework to study the time variation of fundamental constants in a model-independent way. Model independence implies more free parameters than assumed in previous studies. Using data from atomic clocks based on $^{87}$Sr, $^{171}$Yb$^+$ and $^{133}$Cs, we set bounds on parameters controlling the variation of the fine-structure constant, $\alpha$, and the electron-to-proton mass ratio, $\mu$. We consider variations on timescales ranging from a minute to almost a day. In addition, we use our results to derive some of the tightest limits to date on the parameter space of models of ultralight dark matter and axion-like particles.

physics.atom-ph↗

arXiv2022

Snowmass white paper: Need for amplitude analysis in the discovery of new hadrons

We highlight the need for the development of comprehensive amplitude analysis methods to further our understanding of hadron spectroscopy. Reaction amplitudes constrained by first principles of $S$-matrix theory and by QCD phenomenology are needed to extract robust interpretations of the data from experiments and from lattice calculations.

hep-ph↗

arXiv2022

Implications of Quantum Gravity for Dark Matter Searches with Atom Interferometers

In this brief paper, we show that atom interferometer experiments such as MAGIS, AION or AEDGE have the potential to not only probe very light dark matter models, but they will also probe quantum gravity. We show that the linear coupling of a singlet scalar dark matter particle to electrons or photons is already ruled out by our current understanding of quantum gravity coupled to data from torsion pendulum experiments. On the other hand, the quadratic coupling of scalar dark matter to electrons and photons has a large viable parameter space which will be probed by these atom interferometers. Implications for searches of quantum gravity are discussed.

hep-ph↗