arXiv subjects

Jonathan L. Schubert

Publications and source records attributed to Jonathan L. Schubert.

4 recordsLinked to original sources

arXiv2026

Hadronic heavy neutral lepton decays to the limit

Heavy Neutral Leptons are a class of hypothetical particle, motivated by simultaneously solving multiple of the standing issues of the Standard Model. In this work we investigate the decay structure of this type of particle in the hadronic picture for multi-body final states. We propose to link the resulting hadronic description to a partonic description in a seamless transition based on the hadron system's invariant mass. Beyond the impact on the total HNL lifetime, we will show that the multi-hadron channels emerging in this description can constitute interesting experimental signatures.

hep-ph↗

arXiv2026

NO LESS: Novel Opportunities for Light Exotic Searches at the SPS

A powerful way to test models with feebly interacting particles in the MeV to GeV mass range is through proton beam-dump experiments. In this paper, we compare the current sensitivity of CERN's NA62 experiment running in beam-dump mode with that of a hypothetical experiment using the same detectors in a future CERN ECN3 beam-dump facility. When optimising such an experiment, the geometric setup is particularly relevant for the specific new-physics scenario under study, since different production mechanisms can generate different angular distributions of new particles. We show that even the most minimalistic reconfiguration of the existing NA62 experiment's detectors can already provide a very competitive sensitivity and collect data immediately after the beam is available.

hep-ex↗

arXiv2024

On the impact of heavy meson production spectra on searches for heavy neutral leptons

Feebly Interacting Particles are a commonly considered extension to the Standard Model of Particle Physics. In many theoretical frameworks these particles can explain observed physical phenomena which are in tension with the current model. \textsc{ALPiNIST} is a simplified Monte Carlo framework aimed at evaluating past, present, and future, short and long baseline experiments for their sensitivities to different models of Axion-Like Particles. We present the extension of this framework to accommodate new classes of Feebly Interacting Particles with emphasis on Heavy Neutral Leptons. This extension is especially well motivated, solving multiple of the standing issues with the Standard Model at the same time. The fundamental importance of inputs on the resulting parameter sensitivity, and thus the need for a unified simulation set-up, is highlighted.

hep-ph↗

arXiv2022

Neutrinoless double-beta decay at colliders: interference between Majorana states

Heavy neutral leptons (HNLs) are hypothetical particles able to explain several puzzles of fundamental physics, first and foremost - neutrino oscillations. Being sterile with respect to Standard Model interactions, these particles admit Majorana masses, allowing for violation of the total lepton number. Lepton number violating (LNV) processes thus become a key signature of HNLs, pursued by many experiments. In this work, we demonstrate that if HNLs are the sole origin of neutrino masses, destructive interference between Majorana states suppresses the same-sign di-lepton signal. In the phenomenologically interesting case of large HNL couplings, such suppression is akin to the cancellation of HNLs' contributions to neutrino masses. Nevertheless, the signal can be much larger than coming from the Weinberg operator alone. We identify regions of the parameter space of such realistic HNL models where the LNV signal is maximised at the LHC and future FCC-hh. Our results are obtained within the effective W approximation which allows for analytic treatment and gives a clear dependence on the model parameters. Although approximate, they are argued to be correct within a factor of a few.

hep-ph↗