Particle Physics 2019

ATLAS

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

New constraints on Higgs decays to 2nd generation leptons using the full Run-2 data.
First constraints on Higgs self-couplings obtained from the combined interpretation of single Higgs decay and di-Higgs decays.
New measurement of Higgs couplings from the combined interpretation of observed h(125) Higgs decays in Run-2 data.
The first ATLAS ‘general search’ paper was published
New more stringent limits on 3rd generation lepto-quarks from run-2 data

The silicon-strip end-cap detector that will be assembled at Nikhef in the coming years has passed the pre-production readiness review
The hardware for the ATLAS phase-1 deployment of the FELIX Trigger and DAQ system is now in full production
A new RasNik alignment system for the new ‘BIS’ muon chambers that will be installed in ATLAS in 2025 has been designed and prototyped at Nikhef, and is now entering the production phase

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 endcap structures activity coordinator & ITk system engineer: Marcel Vreeswijk
Deputy publications committee chair: Pamela Ferrari
Publication committee & Authorship committee: Frank Filthaut
H→bb/cc physics sugroup convener: Hannah Arnold
Statistics committee: Wouter Verkerke

Combined measurements of Higgs boson production and decay using up to 80 fb⁻¹ of
proton-proton collision data at √s=13 TeV collected with the ATLAS experiment, Phys. Rev. D 101 (2020) 012002
Searches for third-generation scalar leptoquarks in √s=13 TeV pp collisions with the ATLAS detector, JHEP 06 (2019) 144
A strategy for a general search for new phenomena using data-derived signal regions and its application within the ATLAS experiment, Eur. Phys. J. C 79 (2019) 120

Marcel Merk,

Decay-time dependent CP violation studies: the study of the mixing phase φs of Bs0 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

Completion of the production and quality assurance of Velo upgrade detector modules and the manifacturing of two sets of vacuum encapsulation boxes for the detector.
Deinstallation of the VELO-1 vertex detector, the cooling and preparation for the installation of the upgraded detector.
Completion of the production of ColdBox-es for the Scintillating Fiber 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.

Vici: Niels Tuning and Wouter Hulsbergen,
Swiss SNF mobility grant, Maxime Schgubiger,
Marie Curie Fellowship: Suzanne Klaver,
LHCb Thesis prize: Jacco de Vries,
LHCb industry award for 3D systems company through collaboration with Antonio Pellegrino,
Welcome of Maastricht University in the LHCb collaboration.

LHCb, Observation of CP Violation in Charm Decays, Phys.Rev.Lett. 122 (2019) 211803.
LHCb, Search for lepton-universality violation in B+ –>K+ l+ l- decays, Phys.Rev.Lett 122 (2019) 191801.
LHCb, Updated measurement of time-dependent CP-voilating observables in Bs→ J/ψ L+ K- decays, Eur.Phys.J.C. 79 (2019) 706.
LHCb, Test of lepton universality with Λb0 → p K- l+ l- decays, arXiv:1912.08139.
LHCb, Measurement of the Bs→φφ decay and search for the B0 → φφ decay, JHEP 12 (2019) 155.

Raimond Snellings, Marta Verweij

Direct photon elliptic flow in Pb-Pb collisions at √s_NN = 2.76 TeV, Phys. Lett. B 789 (2019) 308
Λc+ production in Pb-Pb collisions at √s_NN = 5.02 TeV, Phys. Lett. B 793 (2019) 212
Measurement of the production of charm jets tagged with D0 mesons in pp collisions at √s = 7 TeV, J. High Energy Phys. 08 (2019) 133
Measurement of prompt D0, D+, D*+, and D+s production in p-Pb collisions at √s_NN = 5.02 TeV, J. High Energy Phys. 12 (2019) 092

Steven Hoekstra

Molecular spectroscopy and structure: theory & experiment (2 papers).
Dedicated cryogenic source has been coupled to decelerator. Decelerator is working in either guiding or deceleration mode.
Setting up a fast-beam EDM measurement.

J. O. Grasdijk, X. F. Bai, I. Engin (et al.), Electro-optic sensor for static fields, Applied Physics B 125 (2019)212
Y. Hao, L. Visscher, S. Hoekstra (et al.), High accuracy theoretical investigations of CaF, SrF, and BaF and implications for laser-cooling, The Journal of Chemical Physics 151 (2019)34302
Lifetime measurements of the A2Π1/2 and A2Π3/2 states in BaF, P. Aggarwal, V. R. Marshall, H. L. Bethlem, A. Boeschoten, A. Borschevsky, M. Denis, K. Esajas, Y. Hao, S. Hoekstra, K. Jungmann, T. B. Meijknecht, M. C. Mooij, R. G. E. Timmermans, A. Touwen, W. Ubachs, S. M. Vermeulen, L. Willmann, Y. Yin, and A. Zapara (NL-eEDM Collaboration) Phys. Rev. A 100, 052503 – (nov. 2019)
Denis, M., Haase, P. A. B., Timmermans, R. G. E., Eliav, E., Hutzler, N. R., & Borschevsky, A. Enhancement factor for the electric dipole moment of the electron in the BaOH and YbOH molecules. Physical Review A, 99(4), [042512] (2019)