The IIHE is thrilled to share some wonderful news: our former colleague, Dr. Cecile Caillol, has been appointed to a permanent research physicist position at CERN, starting in February 2026. Cécile’s exceptional trajectory began at the École Polytechnique de Bruxelles (ULB), where she earned her engineering degree. She then joined the IIHE to conduct her doctoral research in the CMS group with Prof. B. Clerbaux. In 2016, she defended her PhD thesis titled: "Scalar boson decays to tau leptons: in the standard model and beyond". Her early work was marked by prestigious distinctions, including the Robert Brout Prize and the CMS Thesis Award.
Following her time in Brussels, Cecile obtained a postdoctoral research position with the University of Wisconsin-Madison, based at CERN. This international experience allowed her to deepen her expertise in tau physics and trigger systems within CMS. She was then awarded a prestigious 5-year CERN staff position (LD), where she has spent the last few years establishing herself as a key leader within the CMS Collaboration.
She has played a pivotal role in maximizing the experiment's scientific output. Her work focuses on: (i) Data Analysis: Leading innovative searches for New Physics and precision measurements of the Higgs boson, exploiting the increased collision energy and luminosity; (ii) L1 Trigger Leadership: As a key expert in the Level-1 Trigger system, she ensured the high-performance selection of physics events in real-time.
In the field of data analysis, in the last years, Cécile has led a diverse range of high-impact studies across several physics sectors:
New Physics Searches: Most recently, she developed an innovative L1 trigger scouting dataset to search for heavy long-lived charged particles (2025). Her work also includes a search for leptoquarks produced in lepton-quark collisions with couplings to tau leptons (2024), and a search for new resonances decaying into Y(1S) l+l- with 2016 data (2020).
Electroweak Physics: She spearheaded a novel measurement of the tau g-2 in ultra-peripheral gammagamma collision (2024) and conducted a search for rare W boson decays into three charged pions (2019).
Higgs Sector: She has made significant contributions to the Higgs to tau-tau channel notably by measuring its differential production cross-sections (2022). Additionally, she contributed to the study of exotic Higgs boson decays (2016-2020).
Her sustained excellence was recently honored with the 2025 CMS Young Researcher Prize.
This permanent appointment at CERN is a testament to her brilliance and dedication. The IIHE community is proud of her achievements and wishes her a long and successful career at the forefront of fundamental physics.