Theoretical framework for collider neutrino measurements and feebly interacting particle searches at the LHC

• Applicant: Felix Kling, Ph.D.
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 560832035

Collisions at the Large Hadron Collider (LHC) generate an intense and highly energetic neutrino beam in the forward direction. The first detection of these neutrinos by both FASER and SND@LHC marks the beginning of an era of collider neutrino physics. Future measurements have the potential to probe predicted, yet unconfirmed, phenomena in strong interaction, such as gluon saturation and intrinsic charm, and also serve as a laboratory for new physics, for example to search for neutrino oscillations or neutrino-philic particles. In addition, forward physics experiments like FASER are searching for the decay of feebly interacting particles (FIPs), which have, for example, been predicted to explain the nature and observed abundance of dark matter or to address the strong-CP problem. To fully exploit this physics potential, a robust theoretical framework is required that can predict forward particle production with sufficient accuracy, thoroughly describe the phenomenology of FIPs and allow for an interpretation of the experimental results. To achieve this goal, the proposed research will i) provide more precise predictions of the neutrino flux at the LHC, ii) develop a machine-learning-based inference framework describing neutrino production and interactions, iii) assess the potential to probe proton structure, sterile neutrino induced oscillations and new particles, and test them with available data, and iv) implement previously overlooked production modes of FIPs into Monte-Carlo generators. The tools and methodology developed in the grant will be used to interpret first data from LHC Run 3 and to prepare for the larger datasets that will be collected in the future. These efforts contribute to maximizing the return on the significant investments already made at the LHC, enabling unique SM measurements in novel kinematic regimes that provide key inputs for astroparticle physics and enhancing the potential for a transformative discovery at the LHC. This individual research grant application is submitted alongside an application for a Heisenberg Program to obtain a Heisenberg Professorship at the Department of Physics of the University of Bonn. This grant seeks funding for a graduate student and a postdoctoral researcher, who will execute key aspects of the planned research program.

• DFG Programme: Research Grants