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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Measurement of the lifetimes of promptly produced Omega(0)(c) and Xi(9)(c) baryons. Sci. Bull., 67(5), 479–487.
Abstract: A measurement of the lifetimes of the Omega(0)(c) and Xi(0)(c) baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb(-1) collected by the LHCb experiment. The Omega(0)(c) and Xi(0)(c) baryons are produced directly from proton interactions and reconstructed in the pK(-)K(-)pi(+) final state. The Omega(0)(c) lifetime is measured to be 276.5 +/- 13.4 +/- 4.4 +/- 0.7 fs, and the Xi(0)(c) lifetime is measured to be 148.0 +/- 2.3 +/- 2.2 +/- 0.2 fs, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the D-0 lifetime. These results confirm previous LHCb measurements based on semileptonic beauty-hadron decays, which disagree with earlier results of a four times shorter Omega(c)0 lifetime, and provide the single most precise measurement of the Omega(0 )(c)lifetime.
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Borsato, M. et al, Zurita, J., Henry, L., Jashal, B. K., & Oyanguren, A. (2022). Unleashing the full power of LHCb to probe stealth new physics. Rep. Prog. Phys., 85(2), 024201–45pp.
Abstract: In this paper, we describe the potential of the LHCb experiment to detect stealth physics. This refers to dynamics beyond the standard model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.
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Aiola, S., Amhis, Y., Billoir, P., Jashal, B. K., Henry, L., Oyanguren, A., et al. (2021). Hybrid seeding: A standalone track reconstruction algorithm for scintillating fibre tracker at LHCb. Comput. Phys. Commun., 260, 107713–5pp.
Abstract: We describe the Hybrid seeding, a stand-alone pattern recognition algorithm aiming at finding charged particle trajectories for the LHCb upgrade. A significant improvement to the charged particle reconstruction efficiency is accomplished by exploiting the knowledge of the LHCb magnetic field and the position of energy deposits in the scintillating fibre tracker detector. Moreover, we achieve a low fake rate and a small contribution to the overall timing budget of the LHCb real-time data processing.
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Martin Lozano, V., Sanda Seoane, R. M., & Zurita, J. (2023). Z'-explorer 2.0: Reconnoitering the dark matter landscape. Comput. Phys. Commun., 288, 108729–14pp.
Abstract: We introduce version 2.0 of Z'-explorer, a software tool that provides a simple, fast, and user-friendly test of models with an extra U (1) gauge boson (Z') against experimental LHC results. The main novelty of the second version is the inclusion of missing energy searches, as the first version only included final states into SM particles. Hence Z'-explorer 2.0 is able to test dark matter models where the Z' acts as an s-channel mediator between the Standard Model and the dark sector, a widespread benchmark employed by the ATLAS and CMS experimental collaborations. To this end, we perform here the first public reinterpretation of the most recent ATLAS mono-jet search with 139 fb-1. In addition, the corresponding searches in the visible final states have also been updated. We illustrate the power of our code by re -obtaining public plots and also showing novel results. In particular, we study the cases where the Z' couples strongly to top quarks (top-philic), where dark matter couples with a mixture of vector and axial-vector couplings, and also perform a scan in the parameter space of a string inspired Stuckelberg model. Z'-explorer 2.0 is publicly available on GitHub. Program summary Program Title: Z'-explorer 2.0 CPC Library link to program files: https://doi .org /10 .17632 /k7tdp8kwgf .2 Developer's repository link: https://github .com /ro -sanda /Z--explorer-2 .0 Licensing provisions: GPLv3 Programming language: C++ and bash Nature of problem: New SM neutral gauge bosons, Z', are ubiquitously present in models of New Physics. In order to confront these models versus a large and ever-growing library of LHC searches, Z'-explorer 1.0 had already included all final states including Standard Model particles. Notably, the previous version of this tool lacked the so-called invisible final states manifested as a momentum imbalance in the transverse plane (“missing energy”). These searches help to probe mediators into a dark sector, where a dark matter candidate resides. Solution method: Z'-explorer encodes the production cross sections for Z' bosons at the LHC as a function of their mass, allowing for a fast evaluation of the exclusion limits. This version of Z'-explorer includes a careful validation of the latest search with one energetic jet (mono-jet) performed by the ATLAS collaboration. Hence one can now test if a given point in parameter space is excluded by both visible and invisible searches. The modular structure of the code has been kept, which allows for potential additions (low-energy constraints, flavor, extrapolation to future colliders).
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Valero, A., Castillo Gimenez, V., Ferrer, A., Gonzalez, V., Hernandez Jimenez, Y., Higon-Rodriguez, E., et al. (2011). The ATLAS tile calorimeter ROD injector and multiplexer board. Nucl. Instrum. Methods Phys. Res. A, 629(1), 74–79.
Abstract: The ATLAS Tile Calorimeter is a sampling detector composed by cells made of iron-scintillator tiles. The calorimeter cell signals are digitized in the front-end electronics and transmitted to the Read-Out Drivers (RODs) at the first level trigger rate. The ROD receives triggered data from up to 9856 channels and provides the energy, phase and quality factor of the signals to the second level trigger. The back-end electronics is divided into four partitions containing eight RODs each. Therefore, a total of 32 RODs are used to process and transmit the data of the TileCal detector. In order to emulate the detector signals in the production and commissioning of ROD modules a board called ROD Injector and Multiplexer Board (RIMBO) was designed. In this paper, the RIMBO main functional blocks, PCB design and the different operation modes are described. It is described the crucial role of the board within the TileCal ROD test-bench in order to emulate the front-end electronics during the validation of ROD boards as well as during the evaluation of the ROD signal reconstruction algorithms. Finally, qualification and performance results for the injection operation mode obtained during the Tile Calorimeter ROD production tests are presented.
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