https://doi.org/10.1140/epjc/s10052-024-13686-6
Regular Article - Experimental Physics
Long-lived particle reconstruction downstream of the LHCb magnet
1
School of Physics and Astronomy, Monash University, Melbourne, Australia
2
Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
3
Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
4
Center for High Energy Physics, Tsinghua University, Beijing, China
5
Department of Engineering Physics, Tsinghua University, Beijing, China
6
Institute Of High Energy Physics (IHEP), Beijing, China
7
School of Physics State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
8
University of Chinese Academy of Sciences, Beijing, China
9
Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China
10
Consejo Nacional de Rectores (CONARE), San Jose, Costa Rica
11
Université Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France
12
Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
13
Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
14
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
15
Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France
16
LPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, France
17
I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
18
Universität Bonn-Helmholtz-Institut für Strahlen und Kernphysik, Bonn, Germany
19
Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
20
Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
21
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
22
School of Physics, University College Dublin, Dublin, Ireland
23
INFN Sezione di Bari, Bari, Italy
24
INFN Sezione di Bologna, Bologna, Italy
25
INFN Sezione di Ferrara, Ferrara, Italy
26
INFN Sezione di Firenze, Firenze, Italy
27
INFN Laboratori Nazionali di Frascati, Frascati, Italy
28
INFN Sezione di Genova, Genoa, Italy
29
INFN Sezione di Milano, Milan, Italy
30
INFN Sezione di Milano-Bicocca, Milan, Italy
31
INFN Sezione di Cagliari, Monserrato, Italy
32
INFN Sezione di Padova, Padua, Italy
33
INFN Sezione di Perugia, Perugia, Italy
34
INFN Sezione di Pisa, Pisa, Italy
35
INFN Sezione di Roma La Sapienza, Rome, Italy
36
INFN Sezione di Roma Tor Vergata, Rome, Italy
37
Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands
38
Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, Netherlands
39
Faculty of Physics and Applied Computer Science, AGH-University of Krakow, Kraków, Poland
40
Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
41
National Center for Nuclear Research (NCBJ), Warsaw, Poland
42
Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania
43
Affiliated with an institute covered by a cooperation agreement with CERN, Geneva, Switzerland
44
DS4DS, La Salle, Universitat Ramon Llull, Barcelona, Spain
45
ICCUB, Universitat de Barcelona, Barcelona, Spain
46
Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
47
Instituto de Fisica Corpuscular, Centro Mixto Universidad de Valencia - CSIC, Valencia, Spain
48
European Organization for Nuclear Research (CERN), Geneva, Switzerland
49
Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
50
Physik-Institut, Universität Zürich, Zurich, Switzerland
51
NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
52
Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine
53
University of Birmingham, Birmingham, UK
54
H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
55
Cavendish Laboratory, University of Cambridge, Cambridge, UK
56
Department of Physics, University of Warwick, Coventry, UK
57
STFC Rutherford Appleton Laboratory, Didcot, UK
58
School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
59
School of Physics and Astronomy, University of Glasgow, Glasgow, UK
60
Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK
61
Imperial College London, London, UK
62
Department of Physics and Astronomy, University of Manchester, Manchester, UK
63
Department of Physics, University of Oxford, Oxford, UK
64
Massachusetts Institute of Technology, Cambridge, MA, USA
65
University of Cincinnati, Cincinnati, OH, USA
66
University of Maryland, College Park, MD, USA
67
Los Alamos National Laboratory (LANL), Los Alamos, NM, USA
68
Syracuse University, Syracuse, NY, USA
69
Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil
70
School of Physics and Electronics, Hunan University, Changsha City, China
71
Guangdong Provincial Key Laboratory of Nuclear Science, Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Institute of Quantum Matter, South China Normal University, Guangzhou, China
72
Lanzhou University, Lanzhou, China
73
School of Physics and Technology, Wuhan University, Wuhan, China
74
Departamento de Fisica, Universidad Nacional de Colombia, Bogota, Colombia
75
Ruhr Universitaet Bochum, Fakultaet f. Physik und Astronomie, Bochum, Germany
76
Eotvos Lorand University, Budapest, Hungary
77
Van Swinderen Institute, University of Groningen, Groningen, Netherlands
78
Universiteit Maastricht, Maastricht, Netherlands
79
Tadeusz Kosciuszko Cracow University of Technology, Kraków, Poland
80
Universidade da Coruña, A Coruna, Spain
81
Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
82
University of Michigan, Ann Arbor, MI, USA
83
Departement de Physique Nucleaire (SPhN), Gif-Sur-Yvette, France
84
Universidade de Brasília, Brasília, Brazil
85
Centro Federal de Educacão Tecnológica Celso Suckow da Fonseca, Rio De Janeiro, Brazil
86
Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China
87
School of Physics and Electronics, Henan University, Kaifeng, China
88
LIP6, Sorbonne Université, Paris, France
89
Universidad Nacional Autónoma de Honduras, Tegucigalpa, Honduras
90
Università di Bari, Bari, Italy
91
Universita degli studi di Bergamo, Bergamo, Italy
92
Università di Bologna, Bologna, Italy
93
Università di Cagliari, Cagliari, Italy
94
Università di Ferrara, Ferrara, Italy
95
Università di Genova, Genoa, Italy
96
Università degli Studi di Milano, Milan, Italy
97
Università degli Studi di Milano-Bicocca, Milan, Italy
98
Università di Padova, Padua, Italy
99
Università di Perugia, Perugia, Italy
100
Scuola Normale Superiore, Pisa, Italy
101
Università di Pisa, Pisa, Italy
102
Università della Basilicata, Potenza, Italy
103
Università di Roma Tor Vergata, Rome, Italy
104
Università di Siena, Siena, Italy
105
Università di Urbino, Urbino, Italy
106
Universidad de Alcalá, Alcalá de Henares, Spain
107
Facultad de Ciencias Fisicas, Madrid, Spain
108
Department of Physics/Division of Particle Physics, Lund, Sweden
109
CERN, 1211, Geneva 23, Switzerland
a
Fernando.Martinez@ific.uv.es
Received:
27
August
2024
Accepted:
5
December
2024
Published online:
6
January
2025
Charged-particle trajectories are usually reconstructed with the LHCb detector using combined information from the tracking devices placed upstream and downstream of the 4 T m dipole magnet. Trajectories reconstructed using only information from the tracker downstream of the dipole magnet, which are referred to as T tracks, have not been used for physics analysis to date. The challenges of the reconstruction of long-lived particles with T tracks for physics use are discussed and solutions are proposed. The feasibility and the tracking performance are studied using samples of long-lived 
and 
hadrons decaying between 6.0 and 7.6 m downstream of the proton–proton collision point, thereby traversing most of the magnetic field region and providing maximal sensitivity to magnetic and electric dipole moments. The reconstruction can be expanded upstream to about 2.5 m for use in direct searches of exotic long-lived particles. The data used in this analysis have been recorded between 2015 and 2018 and correspond to an integrated luminosity of 6 
. The results obtained demonstrate the possibility to further extend the decay volume and the physics reach of the LHCb experiment.
© The Author(s) 2025
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3.
