Particle Physics

Our Group’s particle physics searches focus on physics both within and Beyond the Standard Model (BSM) - searching for new particles and phenomena that could explain some of the biggest mysteries in physics today.

eV-scale Sterile Neutrinos

Our group has an active research program focused on searches for eV-scale sterile neutrinos, motivated by extensions of the standard three-flavor neutrino oscillation framework. In these models, the presence of an additional sterile state can lead to energy- and zenith-dependent distortions in the atmospheric muon-neutrino flux, including resonant matter effects for neutrinos propagating through the Earth. We search for these signatures using large samples of atmospheric neutrinos observed over a wide range of energies and baselines.

A central component of our work is the development and execution of muon-neutrino disappearance analyses, which are particularly sensitive to sterile-neutrino mixing at the eV mass scale. These analyses rely on precise measurements of neutrino energy and arrival direction, and on detailed comparisons between data and theoretical expectations under both standard and sterile-neutrino hypotheses.

Our group contributes broadly across the full analysis chain. This includes event selection and reconstruction, with an emphasis on improving neutrino energy estimation and separating different event topologies; simulation and modeling, particularly of atmospheric neutrino fluxes and neutrino propagation through the Earth; and systematic uncertainty studies, such as uncertainties in neutrino cross sections, detector response, and the optical properties of the medium. We also play a key role in the development of statistical inference frameworks used to test sterile-neutrino models and to quantify constraints.

Through these efforts, our work helps strengthen the robustness and interpretability of sterile-neutrino searches, ensuring that results are limited by fundamental physics rather than by analysis or modeling assumptions. This program complements our broader interests in neutrino oscillations, detector physics, and searches for physics beyond the Standard Model.

Related publications

Heavy Neutal Leptons

Neutrinos are so tiny – less than a millionth of the mass of an electron – that traditional explanations for how particles get their mass break down.Theories that explain how they can be so tiny, without having no mass at all, need to propose new mechanisms of mass generation. One of these, the Seesaw Mechanism, proposes that a new kind of neutrino called a Heavy Neutral Lepton (HNL) may be responsible. This heavy neutrino would suppress the masses of the other neutrino states, making them orders of magnitude lighter.

We search for HNLs using the IceCube detector. HNLs would produce a distinct “double cascade” signature in IceCube, which, if identified, would be a clear signal of an HNLs.

Charm physics

Our group is also actively engaged in characterizing the physics surrounding the discovery of tau neutrinos, with particular emphasis on their degeneracy in detector signatures with charmed hadrons. Our interest in tau neutrinos is driven by their predominantly astrophysical origin, in contrast to electron and muon neutrinos, which have substantial contributions from conventional atmospheric fluxes. In IceCube, tau neutrinos are typically identifiedthrough their distinctive double-cascade event topology; however, we have recently demonstrated that a significant and previously underappreciated Standard Model background arises from the production of charmed hadrons in neutrino interactions.

Motivated by this realization, we have initiated an inclusive search for tau neutrinos and charmed hadrons within the IceCube Collaboration. This effort represents the first dedicated, analysis-level study of charmed-hadron production and its associated physics in a neutrino telescope. By treating tau neutrinos and charm-induced events within a common framework, this approach enables a unified description of signal and background processes with similar observable signatures, thereby improving the robustness and interpretability of tau-neutrino measurements.

A major fraction of the full analysis pipeline, as well as the software infrastructure underpinning it, is developed within our group. This includes detailed kinematic simulations of charm production in neutrino interactions, a transformer-based event selection framework, and a comprehensive statistical inference pipeline incorporating likelihood-based methods and systematic uncertainties.

Through this inclusive strategy, we aim to achieve an unambiguous characterization of the astrophysical tau-neutrino flux. This, in turn, opens new opportunities to exploit tau-neutrino samples for oscillation studies over astrophysical baselines and for searches for neutrino sources, further advancing the scientific reach of IceCube.