Vukasin Milosevic

The European Committee for Future Accelerators (ECFA) Early Career Researcher's (ECR) panel, which represents the interests of the ECR community to ECFA, officially began its activities in January 2021. In the first two years, the panel has defined its own internal structure, responded to ECFA requests for feedback, and launched its own initiatives to better understand and support the diverse interests of early career researchers. This report summarises the panel composition and structure, as well as the different activities the panel has been involved with during the first two years of its existence.

A group of Early-Career Researchers (ECRs) has been given a mandate from the European Committee for Future Accelerators (ECFA) to debate the topics of the current European Strategy Update (ESU) for Particle Physics and to summarise the outcome in a brief document [1]. A full-day debate with 180 delegates was held at CERN, followed by a survey collecting quantitative input. During the debate, the ECRs discussed future colliders in terms of the physics prospects, their implications for accelerator and detector technology as well as computing and software. The discussion was organised into several topic areas. From these areas two common themes were particularly highlighted by the ECRs: sociological and human aspects; and issues of the environmental impact and sustainability of our research.

The European Committee for Future Accelerators (ECFA) Early-Career Researchers (ECR) Panel was invited by the ECFA Detector R&D Roadmap conveners to collect feedback from the European ECR community. A working group within the ECFA ECR panel held a Townhall Meeting to get first input, and then designed and broadly circulated a detailed survey to gather feedback from the larger ECR community. A total of 473 responses to this survey were received, providing a useful overview of the experiences of ECRs in instrumentation training and related topics. This report summarises the feedback received, and is intended to serve as an input to the ECFA Detector R&D Roadmap process.

A summary of searches for Higgs bosons decaying to invisible particles using the data collected by the CMS experiment is presented.This report focuses on three stages of these analyses.First, the combination of results using data collected during the Run 1 ( √ s = 7 and 8 TeV, with 24.6 fb -1 of total integrated luminosity) and early Run 2 ( √ s = 13 TeV, with 38.2 fb -1 ) data taking periods is presented.This combination places a limit on the B(H → inv) at 0.20 (0.19) in terms of the observed (expected) 95 % Confidence Level (CL) upper limit.It is followed by a look into the currently available results focusing on the entire Run 2 phase of data collection (137 fb -1 ), namely the analyses targeting the VH production mode of the Higgs boson.Lastly, a summary of future prospects is presented in terms of the most sensitive channel of this search, indicating the possibility of further constraining the B(H → inv) to 0.038 during the High Luminosity (HL) phase of operation of the Large Hadron Collider (LHC).

The European Committee for Future Accelerators (ECFA) Early Career Researcher's (ECR) panel, which represents the interests of the ECR community to ECFA, officially began its activities in January 2021. In the first two years, the panel has defined its own internal structure, responded to ECFA requests for feedback, and launched its own initiatives to better understand and support the diverse interests of early career researchers. This report summarises the panel composition and structure, as well as the different activities the panel has been involved with during the first two years of its existence.

The latest results of searches for the invisible decays of the Higgs boson (H$\rightarrow$inv) performed by the CMS Collaboration are presented. These studies represent a combination effort focusing on the data collected during the Run 1 ($\sqrt{s} = $7 and 8 $\mathrm{TeV}$) and the early part of Run 2 ($\sqrt{s} = $13 $\mathrm{TeV}$) period within the Large Hadron Collider (LHC). The combined result is expressed as a 95% Confidence Level (CL) upper limit on the branching fraction and currently stands at $\mathcal{B}$(H$\rightarrow$inv)$<$0.19 (0.15) for the observed (expected) limit. Studies of the Higgs boson decaying to a dimuon pair (H$\rightarrow\mu\mu$) are also presented. This result takes advantage of the complete dataset collected during the Run 2 period and constitutes the first evidence for the H$\rightarrow\mu\mu$ decay with the observed (expected) significance of 3.0 (2.5) $\sigma$ and the measured signal strength, relative to the Standard Model (SM), of $\mu = $1.19$^{\text{+0.41}}_{\text{-0.39}}$(stat)$^{\text{+0.17}}_{\text{-0.16}}$(sys).