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Heavy resonances topical meeting: spin-1
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Europe/Zurich
Virtual
Virtual
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Prompt BSM WG meeting room
Zoom Meeting ID
64765911057
Host
Giuliano Gustavino
Alternative hosts
Zeynep Demiragli, Roberto Franceschini
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Summary
Heavy Resonance topical meeting
The meeting focused on discussing Heavy resonances, with Roberto introducing the agenda and emphasizing the need for better interconnection between experiments and theory. Andrea Thamm was scheduled to give a theoretical overview, but the transcript ended before her presentation began. The group discussed the importance of subscribing to the working group email and announced a future meeting on October 31st about PMSSM. Giuliano mentioned a Google Doc being used to take live meeting minutes, and participants were encouraged to add their names to a table if interested in contributing to task forces related to heavy resonances.
Theory
Andrea Thamm presented a comprehensive overview of spin-1 resonances, focusing on their theoretical motivation and experimental search strategies at the LHC. She explained the simplified model approach as a bridge between explicit new physics models and experimental data, highlighting its ability to capture features of both weakly and strongly coupled scenarios. The discussion included detailed analysis of heavy vector triplets (HVTs) and singlets, with emphasis on production modes like Drell-Yan and vector boson fusion (VBF). Andrea demonstrated that VBF can become the dominant production channel for heavy resonances, particularly in regions where the coupling to quarks is small or zero, and presented benchmark parameter points for future experimental searches.
Andrea Thamm presented on simplified models for spin-1 resonances, highlighting their versatility for triplets and singlets, and discussed the complementarity of collider probes to precision tests. She clarified that RS model limits cannot be directly interpreted in HVT space due to model freedoms, and Mihail pointed out that SU2 doublets can have anomalous couplings to quarks at higher orders. The discussion concluded with Daniel questioning the range of coupling values and mass limits, to which Andrea responded that both very large and very small couplings are theoretically interesting, particularly for strongly coupled models and models sitting at zero couplings.
Atlas
Daniel provided an overview of Atlas's heavy resonance combination efforts, focusing on spin-1 interpretations. He highlighted the importance of combining results across different channels to enhance sensitivity to new physics. Daniel discussed Atlas's previous publications on the topic, including a 2018 combination and a 2024 full Run 2 combination that expanded to include tau and top channels. He also mentioned productive discussions with CMS on sharing information and improving analyses. Daniel concluded by describing how Atlas organized its analysis efforts for the 2024 combination, emphasizing the importance of embedding analysts in the process and having a theory consultant.
Daniel presented results from the 2024 paper, focusing on fermionic and bosonic couplings in various plots. He demonstrated how different channels contribute to exclusion limits, particularly highlighting the importance of VBF channels for exploring specific areas of parameter space. Daniel also discussed a collaboration with Riccardo and Andrea to extend an online calculator to include VBF cross-sections, which allowed for more detailed exploration of high-mass regions. The team plans to further investigate lower coupling values and higher mass ranges in future studies.
Daniel presented on the challenges and potential solutions for exploring parameter spaces in particle physics analyses, focusing on the sharing of likelihoods and multidimensional histograms to enable more comprehensive searches. He discussed the limitations of current methods, including computational constraints and the need for orthogonality between analyses. The group also explored the possibility of extending models to include additional new physics scenarios and the importance of theoretical motivation for different parameter choices. Mahsana raised questions about the inclusion of leptonic couplings in vector boson fusion analyses, which Daniel and others discussed. Giuliano addressed whether VBF is optimal across mass ranges, with concerns about trigger thresholds and low-mass exclusions; while Roberto highlighted the challenge of translating older, non-HVT results into current parameter space.
CMS
Andrea Malara presented new CMS results on spin-one resonance searches, combining 16 different final states and interpreting them within the HPT framework. The combination improved sensitivity across various phase spaces, with notable gains in diboson channels and reduced tensions in some regions. The results, which do not expect new data until the end of Run 3, were discussed in the context of future benchmark scenarios and the need for better coordination between experiments.
The group discussed the production processes of Z' and W' bosons, focusing on their interactions with TB bosons and heavy quarks. Mihail and Andrea debated the interpretation of production cross-sections and the experimental sensitivity to additional jets. Giuliano and Roberto supported and encouraged the exploration of alternative production mechanisms, which in turn motivates constraints on third-generation couplings.
CMS-ATLAS Search Harmonization Discussion
The meeting focused on discussing third-generation searches and harmonizing results between CMS and ATLAS. Participants reviewed recent results, including the impact of boosted techniques, and agreed to continue exploring these analyses. The group emphasized the need to synchronize between experiments, particularly in benchmark models and legacy searches, with a goal of combining results in the future. They also discussed updating benchmarks and harmonizing plots, with a particular focus on HVT and LHC tools. The conversation ended with a call for participants to sign up for future activities via a shared Google document.
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