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Particle Physics 2023

 ATLAS

Programme Leaders

Wouter Verkerke, Frank Filthaut, Ivo van Vulpen (deputy)

Main points: scientific

  • Evidence for Higgs boson decays to Zγ final states (combined with CMS)
  • Measurement of quantum entanglement, in top-quark pair production [briefing]
  • New W-boson mass measurement [briefing]
  • Improved nonresonant di-Higgs search in the bbγγ final state, and interpretation in terms of new Higgs boson interactions (paper appeared in early 2024; see https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HDBS-2021-10/)

Main points: technical

  • The commissioning of the readout of the muon New Small Wheel and the upgraded Level-1 calorimeter trigger has been successfully completed. A second candidate FELIX card for the next (Phase-2) upgrade is being designed, for use with high-throughput applications.
  • The Nikhef contribution to the upgrade of the ATLAS Inner Tracker (ITk) focuses mostly on the assembly of the two strip end-cap structures and the installation of the on-detetor cooling services. Construction of both end-caps was finished in 2023; one end-cap will be transported to DESY (Hamburg) while one will remain at Nikhef for further integration. For this phase, the production of dedicated tooling for petal insertion and the required cold tests has started.
  • For the ATLAS High-Granularity Timing Detector (HGTD), a hopefully final readout ASIC has been designed, as well as (the most complex version of) the peripheral electronics board interfacing with the outside world. A FELIX-based DAQ prototype has been developed with all of the necessary capability for configuration, monitoring, calibration and data taking. The final production of Low-Gain Avalanche Diode (LGAD) sensors has started.

Awards, fellowships etc.

  • CERN Scientific Associate (Pamela Ferrari)
  • CERN Corresponding Associate (Frank Filthaut)

Key positions in collaborations

  • Physics coordinator: Pamela Ferrari
  • Collaboration Board Chairperson Advisory Group member: Wouter Verkerke
  • Statistics committee: Lydia Brenner, Wouter Verkerke
  • Exotics group convener: Flavia Dias
  • Early Career Scientist Board: Hannah Arnold
  • Diversity and Inclusion contact: Clara Nellist
  • Convener of top-quark mass & properties subgroup: Clara Nellist
  • ITk system engineer & global structures coordinator: Marcel Vreeswijk
  • FELIX firmware coordinator: Frans Schreuder
  • FELIX software coordinator: Mark Dönszelmann
  • HGTD DAQ/Luminosity/DCS coordinator: Mengqing Wu
  • HGTD electronics coordinator: Frank Filthaut
  • HGTD Institute Board chairperson: Frank Filthaut

Main papers in 2023

  • “Observation of four-top-quark production in the multilepton final state with the ATLAS detector”, Eur. Phys. J. C 83 (2023) 496
  • “Measurements of Higgs boson production by gluon-gluon fusion and vector-boson fusion using H→WW*→eνμν decays in pp collisions at ⎷s = 13 TeV with the ATLAS detector”, Phys. Rev. D 108 (2023) 032005
  • “Measurements of differential cross sections of Higgs boson production through gluon fusion in the H→WW*→eνμν final state at ⎷s = 13 TeV with the ATLAS detector”, Eur. Phys. J. C 83 (2023) 774
  • “Search for Majorana neutrinos in same-sign WW scattering events from pp collisions at ⎷s =13 TeV”, Eur. Phys. J. C 83 (2023) 824
  • “Evidence of off-shell Higgs boson production from ZZ leptonic decay channels and constraints on its total decay width with the ATLAS detector”, Phys. Lett. B 846 (2023) 138223

LHCb

Programme Leaders

Marcel Merk, Mara Senghi Soares

Main points: scientific

  • High precision measurement of the Bs – anti-Bs meson oscillation frequency using decays of the type Bs → Ds pi.
  • Decay-time dependent CP violation studies: the study of the mixing phase sin2b (φs) of B(s) oscillations using B0→ J/ψKS (Bs→ J/ψ φ) decays and the decay phase γ using Bs → DsK decays.
  • Precise measurement of very rare decays of B0s→μ+μ– including the effective lifetime of this decay. Subsequently, the search for B0→μμ and the relative branching ratio of B0 over Bs for these decays. Furthermore, the search for the even stronger suppressed decays involving electrons and tau leptons: B0(s)→ e+e–, Bc → τν, and of the Lepton Flavor violating decays B0(s)→ e μ.
  • Lepton universality tests in semileptonic b-quark to s-quark decays probing physics beyond the standard model, in particular using the angular distribution variables and with Λb→Λl+l- decays.
  • Searches for long-lived massive particles through signals of displaced as well as emerging jets

Main points: technical

  • Production of Velo upgrade detector modules and the installation of two sets of vacuum encapsulation boxes for the detector.
  • Replacement of vacuum encapsulation boxes for the detector in 2023, to prepare for 2024.
  • Installation of Scintillating Fiber detector modules, the Coldboxes and the cooling infrastructure.
  • Operation of SciFi modules in the C-frames at CERN.
  • Development and commissioning of the real-time reconstruction framework and implementation of reconstruction algorithms.

Awards, fellowships etc.

  • Veni: Andrii Usachov, Jacco de Vries, Suzanne Klaver
  • Vidi: Keri Vos
  • Vici: Niels Tuning, Wouter Hulsbergen
  • ENW-M1: Patrick Koppenburg, Keri Vos
  • ENW-XL (FASTER): Kazu Akiba, Kristof de Bruijn
  • Surf Grant: Marcel Merk, Jacco de Vries
  • IBM-Zurich Research Grant: Miriam Lucio Martinez

Key positions in collaborations

  • Dutch representative: Mara Senghi Soares
  • Run Coordinator: Niels Tuning
  • Speakers Bureau chair: Keri Vos
  • Velo Deputy project leader: Kazu Akiba
  • Data Processing and Analysis deputy project leader: Patrick Koppenburg
  • Upgrade II tracking coordinator: Marcel Merk
  • Working group convenor of QCD, Electroweak and Exotics: Andrii Usachov
  • Working group convenor of Very Rare Decays: Jacco de Vries
  • Data Quality Coordinator: Suzanne Klaver
  • Reconstruction Coordinator: Maarten van Veghel
  • Scintillating Fiber Tracker Electronics Coordinator: Wilco Vink

Main papers in 2023

ALICE

Programme Leader

Raimond Snellings, Marta Verweij (deputy)

Main points: scientific

  • Measurements of transport properties of Quark Gluon Plasma
  • Constraints on magnitude chiral magnetic effect
  • Charm baryon and meson cross-sections as function of multiplicity in proton-proton collisions

Main points: technical

  • Installation of the upgrade of inner-tracking system at CERN, commissioning and first data taking.
  • Research and development for 4D tracking technology for ITS3 (run 3+4) and ALICE3 (run 5)

Key positions in collaborations

  • Elected Spokesperson : M. van Leeuwen
  • Upgrade coordinator : M. van Leeuwen
  • Physics Working Group Convenor: M. Verweij
  • System Run Coordinator: I. Ravasenga
  • Conference Committee: A. Grelli
  • Editorial Board: P. Christakoglou, T. Peitzmann

Awards, fellowships etc.

  • Vici: Marco van Leeuwen
  • Start-up: Marta Verweij

Main papers in 2022

  • The ALICE Collaboration. Measurement of anti-3He nuclei absorption in matter and impact on their propagation in the Galaxy. Nat. Phys. 19, 61–71 (2023). 10.1038/s41567-022-01804-8
  • Measurement of the Groomed Jet Radius and Momentum Splitting Fraction in pp and Pb-Pb Collisions at 5.02 TeV. S. Acharya et al. (A Large Ion Collider Experiment Collaboration) Phys. Rev. Lett. 128, 102001 – Published 7 March 2022
  • The Alice Collaboration. Direct observation of the dead-cone effect in quantum chromodynamics. Nature 605 (2022) 7910, 440-446, Nature 607 (2022) 7920, E22 (erratum).  10.1038/s41586-022-04572-w, 10.1038/s41586-022-05026-z
  • First demonstration of in-beam performance of bent Monolithic Active Pixel Sensors, Nucl.Instrum.Meth.A 1028 (2022) 166280,  10.1016/j.nima.2021.166280

eEDM

Programme Leader

Steven Hoekstra

Main points: scientific

  • No information

Main points: technical

  • No information

Awards, fellowships etc.

  • No information

Main papers in 2023

  • No information