* Particle Physics

ATLAS

Programme Leaders

Wouter Verkerke, Nicolo de Groot

Main points: scientific

  • Observation of Higgs boson production in association with a top quark pairs
  • Observation of Higgs boson decay to pairs of b-quarks
  • News article in Nature on the general search strategy interviewing Sascha Caron
  • A new strategy has been developed to study polarized single top quark production (jointly with the Nikhef theory group)
  • New stringent limits set on lepton flavor violation in Z boson decays

Main points: technical

  • A record luminosity of 158 fb–1 has been delivered to the ATLAS detector at the end of LHC run-2
  • The silicon-strip end-cap detector that will be assembled at Nikhef in the coming years has passed the final design review
  • The hardware for the ATLAS phase-1 deployment of the FELIX Trigger and DAQ system is entering the production phase
  • Tristan du Pree takes over muon project leadership from Gerjan Bobbink

Awards, fellowships etc.

  • ATLAS Outstanding achievement award – Olga Igonkina
  • NWO Veni grant – Nikolina Ilic
  • CERN fellowship – Sara Alderweireldt

Key positions in collaborations

  • Coordinators B-physics, Muon trigger: Olya Igonkina, Marcus Morgenstern, resp.
  • FELIX firmware coordinator: Frans Schreuder
  • FELIX software coordinator: Mark Dönszelmann
  • FELIX user support coordinator: Nikolina Ilic
  • ITk global endcap structures activity coordinator: Marcel Vreeswijk
  • Deputy publications committee chair elect: Pamela Ferrari
  • Statistics committee: Wouter Verkerke

Main papers in 2018

  • Observation of Higgs boson production in association with a top quark pair at the LHC with the ATLAS detector, Phys. Lett. B 784 (2018) 173
  • Observation of H→bb̅ decays and VH production with the ATLAS detector, Phys. Lett. B 786 (2018) 59
  • A search for lepton-flavor-violating decays of the Z boson into a tau-lepton and a light lepton with the ATLAS detector, Phys. Rev. D 98 (2018) 092010
  • Effective operators in t-channel single top production and decay,  Eur.Phys.J. C78 (2018) no.11, 919

LHCb

Programme Leader

Marcel Merk

Main points: scientific

  • Decay-time dependent CP violation studies: the study of the mixing phase φs of B0 oscillations using 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 first observation of B0→μμ and the relative branching ratio of B0 over Bs for these decays. Furthermore, the search for the even stronger suppressed decays B0(s)→ e+e 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,
  • Searches for long-lived massive particles through signals of displaced as well as emerging jets

Main points: technical

  • Completion of the mass production and quality assurance of Velo upgrade detector modules and the manufacturing of two sets of vacuum encapsulation boxes for the detector.
  • Deinstallation of the VELO- 1vertex detector, the cooling and preparation for the installation of the upgraded detector.
  • Completion of the production of ColdBox-es for the Scintillating Fibar detector.
  • Installation and testing 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.

  • Vici: Niels Tuning and Wouter Hulsbergen,
  • Marie Curie Fellowship: Sean Benson,
  • LHCb Early career scientist prize: Elena Dall’Occo.

Key positions in collaborations

  • Run coordinator: Niels Tuning,
  • Editorial Board Chair: Patrick Koppenburg,
  • Outer Tracker project leader: Niels Tuning,
  • SciFi deputy project leader: Antonio Pellegrino,
  • Real Time Analysis Institute Board chair: Marcel Merk.
  • Working group convenor of B to CC decays: Sevda Esen,
  • Working group convenor of rare decays: Flavio Archilli,
  • Stripping coordinator: Carlos Vazquez Sierra.

Main papers in 2018

  • LHCb, Physics case for an LHCb Upgrade II –  Opportunities in flavour physics, and beyond, in the HL-LHC era, arXiv:1808.08865.
  • LHCb, Measurement of the CKM angle γ using B±→ DK± with D→ KS0π+π, KS0 K+K decays, DOI 10.1007/JHEP08(2018)176.
  • LHCb, Observation of a new Ξb resonance,  DOI:10.1103/PhysRevLett.121.072002.
  • Bel, S.Esen, N. Tuning, M. Merk et al., Measurement of CP asymmetry in Bs0→ Ds* K± decays, DOI 10.1007/JHEP03(2018)059.

ALICE

Programme Leader

Raimond Snellings

Main points: scientific

  • Measurements of transport properties QGP
  • Constraints on magnitude chiral magnetic effect

Main points: technical

  • First staves completed of upgrade ITS and on track for finishing in 2019

Key positions in collaborations

  • Physics coordinator : Marco van Leeuwen
  • Project leader ITS: Paul Kuijer)
  • Physics Working Group Convenors: A. Grelli
  • Physics Analysis Group Coordinators: B. Trzeciak, D. Caffari,
  • Junior Representative: M. Sas
  • Conference Committee: P. Christakoglou

Awards, fellowships etc.

  • J. Margutti Cum Laude Thesis
  • B. Trzeciak: price best talk Quark Matter 2018
  • M. Sas: price best poster Quark Matter 2018

Main paper in 2018

  • Energy dependence and fluctuations of anisotropic flow in Pb-Pb collisions at √sNN =5.02 and 2.76 TeV, ALICE collaboration,  J. High Energ. Phys. (2018) 2018: 103. https://doi.org/10.1007/JHEP07(2018)103
  • Measurement of D0, D+, D*+ and D+s production in Pb-Pb collisions at √sNN =5.02 TeV, J. High Energy Phys. 10 (2018) 174 , https://doi.org/10.1007/JHEP10%282018%29174
  • Neutral pion and η meson production in p-Pb collisions at √sNN = 5.02 TeV, Eur. Phys. J. C 78 (2018) 624 , https://doi.org/10.1140/epjc/s10052-018-6013-8

eEDM

Programme Leader

Steven Hoekstra

Main points: scientific

  • Studied and determined key properties of the BaF electronic structure (energies, lifetimes, branching ratios) with implications for molecular laser cooling
  • Calculated the hyperfine constants and the effective electric field in BaF
  • Optimized the properties of a cryogenic beam of SrF molecules
  • Obtained a complete set of SrF deceleration data and analyzed them by a careful comparison to numerical trajectory simulations, characterizing the stability in the deceleration process

Main points: technical

  • A prototype transformer for the high-voltage upgrade of the molecule decelerator is being tested
  • A cryogenic buffer gas source for slow molecular beam has been constructed and is operational
  • The interaction zone of the electron-EDM experiment has been designed, and first prototypes are being constructed
  • An intense supersonic source of BaF molecules has become operational, and first measurements on molecular properties are underway.

Main paper in 2018

  • Measuring the electric dipole moment of the electron in BaF – The NL-eEDM collaboration, Aggarwal, P., Bethlem, H.L. et al. Eur. Phys. J. D (2018) 72: 197. https://doi.org/10.1140/epjd/e2018-90192-9