Forward decay chain reconstruction with displaced vertices in intense magnetic fields
Abstract
Precise reconstruction of particle decay chains is essential for a broad range of analyses in particle physics experiments, particularly those targeting flavour physics and spectroscopy. We present a standalone, modular and extensible decay tree reconstruction framework designed to handle complicated topologies, accounting for tightly constrained particle decays and long-distance trajectory extrapolations through regions of intense and inhomogeneous magnetic field, as well as limited momentum resolution. Implemented in C++, the framework is optimised for configurability and performance. Developed primarily within CERN's LHCb experiment, its focus is on decay chains with vertices located several metres from the LHC proton-proton interaction point, where the dipole magnetic field is maximal and non-uniform. Even so, it remains flexible: it can accommodate these special cases as well as the approximations commonly used in standard decay tree fitting tools, and the geometries of general-purpose collider detectors. Benchmark studies using simulated data demonstrate significant improvements in reconstruction efficiency, invariant mass resolution, and vertex position resolution with respect to existing tools, opening new opportunities for precision measurements and searches involving highly displaced decays.
Related
- Earth-scale searches for displaced vertices: KM3NeT meets the LHC
- Probing νSMEFT at Belle II with displaced dilepton vertices
- Extending the reconstruction of displaced tracks at CMS during the HL-LHC with Line Segment Tracking
- Magnetic shocks generated by two counterstreaming plasma jets induced by an intense femtosecond laser pulse
- Induced nonlinear phase shift of forward volume spin waves in magnetic films and one-dimensional magnonic crystals
BibTeX
@misc{elles2026forward,
title = {{Forward decay chain reconstruction with displaced vertices in intense magnetic fields}},
author = {Sergio Javier Jaimes Elles and Simone Libralon and Fernando Martinez Vidal and Nicola Neri and Miguel Rebollo de Miguel and Izaac Sanderswood and Volodymyr Svintozelskyi and Giorgia Tonani and Javier Velilla Serna and Ziyi Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.14666},
eprint = {2610.14666},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.14666},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Forward decay chain reconstruction with displaced vertices in intense magnetic fields
AU - Sergio Javier Jaimes Elles
AU - Simone Libralon
AU - Fernando Martinez Vidal
AU - Nicola Neri
AU - Miguel Rebollo de Miguel
AU - Izaac Sanderswood
AU - Volodymyr Svintozelskyi
AU - Giorgia Tonani
AU - Javier Velilla Serna
AU - Ziyi Wang
PY - 2026
DA - 2026/10/10
PB - arXiv
DO - 10.48550/arxiv.2610.14666
UR - https://arxiv.org/abs/2610.14666
AB - Precise reconstruction of particle decay chains is essential for a broad range of analyses in particle physics experiments, particularly those targeting flavour physics and spectroscopy. We present a standalone, modular and extensible decay tree reconstruction framework designed to handle complicated topologies, accounting for tightly constrained particle decays and long-distance trajectory extrapolations through regions of intense and inhomogeneous magnetic field, as well as limited momentum resolution. Implemented in C++, the framework is optimised for configurability and performance. Developed primarily within CERN's LHCb experiment, its focus is on decay chains with vertices located several metres from the LHC proton-proton interaction point, where the dipole magnetic field is maximal and non-uniform. Even so, it remains flexible: it can accommodate these special cases as well as the approximations commonly used in standard decay tree fitting tools, and the geometries of general-purpose collider detectors. Benchmark studies using simulated data demonstrate significant improvements in reconstruction efficiency, invariant mass resolution, and vertex position resolution with respect to existing tools, opening new opportunities for precision measurements and searches involving highly displaced decays.
ER -