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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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Bartl, A., Eberl, H., Herrmann, B., Hidaka, K., Majerotto, W., & Porod, W. (2011). Impact of squark generation mixing on the search for squarks decaying into fermions at LHC. Phys. Lett. B, 698(5), 380–388.
Abstract: We study the effect of squark generation mixing on squark production and decays at LHC in the Minimal Supersymmetric Standard Model (MSSM). We show that the effect can be very large despite the very strong constraints on quark-flavour violation (QFV) from experimental data on B mesons. We find that the two lightest up-type squarks (u) over bar (1.2) can have large branching ratios for the decays into c (chi) over bar (0)(1) and t (chi) over bar (0)(1) at the same time due to squark generation mixing, leading to QFV signals 'pp -> c (t) over bar (t (c) over bar) + missing-E-T + X' with a significant rate. The observation of this remarkable signature would provide a powerful test of supersymmetric QFV at LHC. This could have a significant impact on the search for squarks and the determination of the underlying MSSM parameters.
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Sanchis-Lozano, M. A., Sarkisyan-Grinbaum, E. K., & Moreno-Picot, S. (2016). Searching for hidden sector in multiparticle production at LHC. Phys. Lett. B, 754, 353–359.
Abstract: We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.
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Miñano, M. (2011). Radiation Hard Silicon Strips Detectors for the SLHC. IEEE Trans. Nucl. Sci., 58(3), 1135–1140.
Abstract: While the Large Hadron Collider (LHC) began taking data in 2009, scenarios for a machine upgrade to achieve a much higher luminosity are being developed. In the current planning, it is foreseen to increase the luminosity of the LHC at CERN around 2018. As radiation damage scales with integrated luminosity, the particle physics experiments will need to be equipped with a new generation of radiation hard detectors. This article reports on the status of the R&D projects on radiation hard silicon strips detectors for particle physics, linked to the Large Hadron Collider Upgrade, super-LHC (sLHC) of the ATLAS microstrip detector. The primary focus of this report is on measuring the radiation hardness of the silicon materials and the detectors under study. This involves designing silicon detectors, irradiating them to the sLHC radiation levels and studying their performance as particle detectors. The most promising silicon detector for the different radiation levels in the different regions of the ATLAS microstrip detector will be presented. Important challenges related to engineering layout, powering, cooling and reading out a very large strip detector are presented. Ideas on possible schemes for the layout and support mechanics will be shown.
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