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High-Energy Hadron Interactions at the CERN LHC with the ATLAS and the FASER experiments

English title High-Energy Hadron Interactionsat the CERN LHC with the ATLAS and the FASER experiments
Applicant Iacobucci Giuseppe
Number 188489
Funding scheme Project funding
Research institution Département de physique nucléaire et corpusculaire Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Particle Physics
Start/End 01.10.2019 - 30.09.2022
Approved amount 1'603'005.00
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Keywords (6)

Elementary particle physics; Searches for new physics; LHC; ATLAS experiment; Silicon tracker; FASER experiment

Lay Summary (Italian)

La ricerca di nuova fisica con i dati degli esperimenti ATLAS e FASER al Large Hadron Collider del CERN.
Lay summary

Il Large Hadron Collider (LHC), in funzione al CERN dal 2010, ha prodotto vari risultati importanti, in primis la scoperta e lo studio delle proprietà de bosone di Higgs, la particella elementare che ha spiegato il meccanismo che permette alle particelle elementari di avere una massa.

Il gruppo del Département de physique nucléaire et corpusculaire dell’Università di Ginevra analizzerà i dati dell'esperimento ATLAS relativi alle collisioni a più alta energia trasversale alla ricerca di particelle molto pesanti, non previste dal Modello Standard, che decadono in due borsoni vettori WW, ZZ o WZ. In questo progetto di ricerca, tali stati finali verranno selezionati nei decadimenti dei bosoni W o Z in adroni. La novità della ricerca risiede nel ricorso alla misura della polarizzazione dello stato finale come tool per la riduzione degli eventi di fondo.

Una possibilità alternativa al tipo di ricerche possibili con il rivelatore ATLAS, e` fornita dall'esperimento FASER, uno spettrometro di piccole dimensioni che sarà` installato a 480 m dal punto di interazione di ATLAS ad un angolo di zero gradi rispetto all'asse di collisione dei fasci. L'idea originale e` di sfruttare l'enorme flusso di adroni leggeri prodotti ad angolo zero, per poter studiare l'eventuale transizione di tali adroni leggeri in particelle altrettanto leggere non ancora scoperte, che potrebbero spiegare, per esempio, la presenza della materia oscura nell'universo ed aprire la nostra conoscenza verso nuove interazioni ancora più fondamentali di quelle descritte nel Modello Standard.

Direct link to Lay Summary Last update: 29.09.2019

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
173598 FLARE: Maintenance & Operation for the LHC Experiments 2017-2020 01.04.2017 FLARE
169000 High-Energy Hadron Interactions: ATLAS at the CERN LHC 01.10.2016 Project funding
201474 A high-granularity silicon pre-shower detector as a tool for discovery with the FASER experiment at the LHC 01.04.2021 FLARE
201478 FLARE - ATLAS Detector Operation and Phase-II Upgrade at the CERN Large Hadron Collider (LHC) 01.04.2021 FLARE
173601 FLARE - ATLAS Detector Operation and Phase-II Upgrade at the CERN Large Hadron Collider (LHC) 01.04.2017 FLARE


Over the last three years, this research group concentrated on the search for physics beyond the Standard Model by maximally exploiting the available ATLAS dataset and on the design and prototyping of the future ATLAS Pixel detector for the High-Luminosity LHC. In this funding request, we propose to continue these two research paths and supplement them by contributing to the FASER experiment, which looks for new physics at the LHC following a very different strategy. We have been the leading force in the ATLAS experiment in the search for new physics in di-boson boosted hadronic final states and have introduced a new method, the Track-Calorimeter Cluster, which simultaneously exploits the ATLAS tracker and calorimeter systems for optimal reconstruction of hadronic events of the highest energies. We have demonstrated that this method results in an enormous jump in sensitivity in the search for new high-mass bosons of spin-0, 1 or 2, well beyond that provided by the increase in luminosity. Due to this great success, the method is now centrally adopted in ATLAS and constitutes the solid foundation of many present and future journal publications of the Collaboration. For the three years of this research project, we propose to further improve the method, thereby increasing sensitivity to specific final-states dependent on electroweak-boson polarizations or to the Higgs-boson coupling to bottom quarks. Two postdocs and two PhD students are requested to continue this very important activity at the high-energy frontier.Since the upcoming 2021-2023 data-taking period will only double the integrated luminosity, it is of extreme importance to increase the integrated luminosity of the experiment by an order of magnitude, thus fully exploiting the LHC infrastructure. This will be achieved with the High-Luminosity LHC (HL-LHC) program, which foresees 3000 fb-1 of data to be collected in 2026-2038. The ATLAS detector was not designed for such extreme experimental conditions and radiation doses, and therefore it needs to be upgraded. In particular, ATLAS will need a new silicon tracker, which includes a five-layer pixel detector extending the charged-particle acceptance to |?| = 4. The construction of the three layers of the Outer-Barrel pixel detector, which this group designed and engineered together with CERN-DT, constitutes a fundamental part of this research project, supported for its CORE costs by the FLARE grant 20FL20_173601. We propose to continue our ongoing effort with the prototyping, pre-production and production of: i) 50% of the local supports of the Outer-Barrel Pixel detector and ii) 100% of the Patch-Panel 0 boards that are entirely under our responsibility. These activities will be performed in the DPNC cleanrooms by one of the requested postdocs in collaboration with the engineers of the Department and other technical personnel. The postdoc will also participate in the maintenance work and re-commissioning during the present LHC long shutdown as well as in operation of the ATLAS Pixel detector during the next data-taking period.Despite the great performance of the LHC, which has provided luminosity exceeding predictions, and of the excellent ATLAS efficiency in data acquisition and analysis, unfortunately there have not yet been signs of new physics in the pp collisions dataset. The standard collider strategy of using an enormous quantity of high-energy collisions to produce new high-mass particles, which for example resulted in the discovery of the Higgs boson by ATLAS and CMS, may not be the optimal approach to search for less direct types of physics beyond the Standard Model. For this reason, we decided to complement our searches with an orthogonal approach. This is achieved in this research proposal through the FASER experiment, a small detector positioned 480m downstream the ATLAS interaction point at zero angle w.r.t. the axis of the colliding beams, which will exploit the enormous number of collisions at the ATLAS interaction point to look for very rare decays into the low-mass long-lived particles (dark photons, CP-odd states, axion-like particles) advocated to be the portal towards a new physics sector still to be discovered. We propose to provide a major contribution to the construction, installation and commissioning of the FASER detector, and then to analyse the data. The third PhD student position previously granted for ATLAS is requested to be assigned to this activity.