Research
I do research on neutrino physics, specifically in neutrino oscillations and neutrino cross sections.
For my PhD research, I focused on performing a search for Heavy Neutral Leptons (postulated neutrino states mixing primarily with sterile flavour eigenstates, of at least a few hundred MeV/c^2 mass) with data from the MINERvA detector at Fermilab.
During that time, I developed (in conjunction with my supervisor, Dr. Xianguo Lu) an accurate simulation module that has since been incorporated into the ubiquitous GENIE event generator. This module correctly accounts for effects of the position of neutrino production along a beamline, and applies relativistic kinematics to extract accurate spectra for HNL decays in a detector of given size and location (Phys. Rev. D 107 (2023) 055003). I have expanded this module recently to handle generic long-lived products.
I am currently working on the SBND experiment at Fermilab, primarily on searching for sterile neutrino via muon disappearance using the VALOR toolkit. I am also involved in SBND operations, and I maintain the near- and far- detector software stacks.
Neutrino mass and oscillations
The definite observation of neutrino oscillations showed that the Standard Model, which was constructed with the assumption that neutrino masses are exactly zero, is incomplete. However, we still do not have a definite understanding of where neutrino masses (which, for the "active" neutrinos which interact with matter, are very small, much smaller than the electron mass) arise from.
Various explanations for the neutrino masses include the various types of "seesaw mechanism", where heavy degrees of freedom extend the leptonic mixing matrix and source light neutrino mass eigenstates; realisations for these heavy states can be as low as O(100 MeV/c^2), such as in the "nuMSM" (or neutrino minimal standard model, Phys. Lett. B (2005) 631).
These "minimal" extensions imply the existence of new degrees of freedom which might be detectable in modern high-precision neutrino detectors; I am working on accurately modelling the fluxes of such particles, and accurately simulating the signatures they might leave in detectors.
Another explanation invokes a "sterile" neutrino of order eV-keV/c^2; light eV-scale neutrinos could show as "disappearance" signatures in an oscillation analysis, with no corresponding appearance in any active neutrino flavour, whereas heavier keV-scale neutrinos could act as "warm" dark matter that free-streams in the early Universe, damping out fluctuations in the energy density of the early Universe. A number of short-baseline anomalies (where measurements between two neutrino detectors close to each other, typically at a low neutrino energy, show discrepancies between expectation and observation) have been detected (see e.g. Phys. Rep. 928 (2021) 1-63), motivating a dedicated short-baseline neutrino (SBN) oscillation programme at Fermilab to investigate these.
I am working in SBN to leverage the wealth of data from the near detector (SBND) and from the far detector (ICARUS) to perform a muon neutrino disappearance analysis, with a goal to either detect a sterile neutrino, or provide world-leading constraints on the sterile neutrino parameter space.
Simultaneously, keV-scale sterile neutrinos can be constrained both through direct astrophysical searches, and through observations of large-scale structure in the late Universe, and of the cosmic microwave background power spectrum (see for example Prog. Nuc. Part. Phys. 104 (2019) 1-45).
Neutrino flux modelling
Accurate knowledge of neutrino fluxes is critical for estimating not only overall event rates at detectors, but also for relative normalisations of interaction types of the active neutrinos.
Furthermore, accurate knowledge of the mechanisms that produce neutrinos (overwhelmingly, the decay of mesons) is required for the precise propagation of systematic uncertainties for both active neutrinos and any exotic long-lived particles (or dipole-portal neutrinos) to an analysis.
I am working within SBN to upgrade the flux simulation from the Booster Neutrino Beam (BNB) to modern Geant4, with a view to use the rich flux drivers packaged with dk2nu to propagate systematic uncertainties to BSM simulations as well as Standard Model neutrinos.
Neutrino-nucleus interactions
Neutrino-nucleus interactions in the GeV range are currently a dominant source of systematic uncertainty in both neutrino oscillation experiments and for Beyond the Standard Model searches (for an overview of GeV-range neutrino interactions see e.g. EPJ Special Topics 230 (2021) 4243).
As part of GENIE, I am interested in leveraging existing high-statistics neutrino datasets to perform a global analysis of scattering data, so that these uncertainties may be constrained to a high precision. A previous example of how multiple datasets from deuterium and hydrogen bubble chamber experiments led to tuning of neutrino-induced hadronisation can be found in Phys. Rev. D 105 (2022) 012009.
Within SBND, I am also interested in using the wealth of high-statistics and high-quality data obtained by the detector to constrain systematic uncertainties at the far detector, ICARUS.
Research collaborations
Komninos John Plows
SBND
Short Baseline Neutrino Detector (https://sbn-nd.fnal.gov/)
Komninos John Plows
MINERvA
Main Injector Neutrino ExpeRiment to study v-A interactions (https://minerva.fnal.gov/)
Komninos John Plows
GENIE
The GENIE collaboration (https://hep.ph.liv.ac.uk/~costasa/genie/collaboration.html) plays the leading role in developing a modern and universal neutrino event generator framework, including a validated and consistent implementation for physics modelling elements for neutrino, charged lepton, and hadron-nucleus scattering and BSM processes. More details on https://github.com/GENIE-MC