J. D'Hondt

Search for lepton-flavour-violating decays of the Higgs boson

A direct search for lepton flavour violating decays of the Higgs boson in the H→ μτ channel is described. In particular, the search examines the H → μτe and the H → μτh channels, where the τ leptons are reconstructed in the electronic and hadronic decay channels respectively. The data sample used in the search was collected in proton-proton collisions at √ s = 13 TeV with the CMS experiment at the LHC and corresponds to an integrated luminosity of 2.3 fb−1. No excess is observed, and a 95% CL upper limit of B(H→ μτ) < 1.20% (1.62 expected) is obtained.

Search for supersymmetry in the multijet and missing transverse momentum final state in pp collisions at 13 TeV

A search for new physics is performed based on all-hadronic events with large missing transverse momentum produced in proton-proton collisions at √ s = 13 TeV. The data sample, corresponding to an integrated luminosity of 2.3 fb−1, was collected with the CMS detector at the CERN LHC in 2015. The data are examined in search regions of jet multiplicity, tagged bottom quark jet multiplicity, missing transverse momentum, and the scalar sum of jet transverse momenta. The observed numbers of events in all search regions are found to be consistent with the expectations from standard model processes. Exclusion limits are presented for simplified supersymmetric models of gluino pair production. Depending on the assumed gluino decay mechanism, and for a massless, weakly interacting, lightest neutralino, lower limits on the gluino mass from 1440 to 1600 GeV are obtained, significantly extending previous limits. Published in Physics Letters B as doi:10.1016/j.physletb.2016.05.002. c

Measurement of the hadronic activity in events with a Z and two jets and extraction of the cross section for the electroweak production of a Z with two jets in pp collisions at s√ = 7 TeV

A bstractThe first measurement of the electroweak production cross section of a Z boson with two jets (Zjj) in pp collisions at

Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at sNN=2.76TeV with the CMS experiment

\sqrt{s}=7

A novel segmented-scintillator antineutrino detector

TeV is presented, based on a data sample recorded by the CMS experiment at the LHC with an integrated luminosity of 5 fb−1. The cross section is measured for the ℓℓjj (ℓ = e, μ) final state in the kinematic region mℓℓ> 50 GeV, mjj> 120 GeV, transverse momenta

ϒ(nS) polarizations versus particle multiplicity in pp collisions at s=7 TeV

p_{\mathrm{T}}^{\mathrm{j}}>25

Study of Jet Quenching with Z+jet Correlations in Pb-Pb and pp Collisions at s NN=5.02 TeV

GeV and pseudorapidity |ηj| < 4.0. The measurement, combining the muon and electron channels, yields σ = 154 ± 24 (stat.) ± 46 (exp. syst.) ± 27 (th. syst.) ± 3 (lum.) fb, in agreement with the theoretical cross section. The hadronic activity, in the rapidity interval between the jets, is also measured. These results establish an important foundation for the more general study of vector boson fusion processes, of relevance for Higgs boson searches and for measurements of electroweak gauge couplings and vector boson scattering.

Measurement of inclusive jet cross sections in pp and PbPb collisions at s NN =2.76 TeV

Article history: Received 23 May 2016 Received in revised form 21 June 2017 Accepted 3 July 2017 Available online 8 July 2017 Editor: M. Doser

Measurement of the inelastic cross section in proton–lead collisions at √sNN=5.02 TeV

The next generation of very-short-baseline reactor experiments will require compact detectors operating at surface level and close to a nuclear reactor. This paper presents a new detector concept based on a composite solid scintillator technology. The detector target uses cubes of polyvinyltoluene interleaved with 6LiF:ZnS(Ag) phosphor screens to detect the products of the inverse beta decay reaction. A multi-tonne detector system built from these individual cells can provide precise localisation of scintillation signals, making efficient use of the detector volume. Monte Carlo simulations indicate that a neutron capture efficiency of over 70 % is achievable with a sufficient number of 6LiF:ZnS(Ag) screens per cube and that an appropriate segmentation enables a measurement of the positron energy which is not limited by γ-ray leakage. First measurements of a single cell indicate that a very good neutron-gamma discrimination and high neutron detection efficiency can be obtained with adequate triggering techniques. The light yield from positron signals has been measured, showing that an energy resolution of 14%/√E(MeV) is achievable with high uniformity. A preliminary neutrino signal analysis has been developed, using selection criteria for pulse shape, energy, time structure and energy spatial distribution and showing that an antineutrino efficiency of 40% can be achieved. It also shows that the fine segmentation of the detector can be used to significantly decrease both correlated and accidental backgrounds.

Measurement of differential cross sections for Higgs boson production in the diphoton decay channel in pp collisions at \sqrt{s}=8TeV

The polarizations of the ϒ(1S)ϒ(1S), ϒ(2S)ϒ(2S), and ϒ(3S)ϒ(3S) mesons are measured as a function of the charged particle multiplicity in proton–proton collisions at View the MathML sources=7 TeV. The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb−1. The results are extracted from the dimuon decay angular distributions, in two ranges of ϒ(nS)ϒ(nS) transverse momentum (10–15 and 15–35 GeV), and in the rapidity interval |y|<1.2|y|<1.2. The results do not show significant changes from low- to high-multiplicity pp collisions, although large uncertainties preclude definite statements in the ϒ(2S)ϒ(2S) and ϒ(3S)ϒ(3S) cases.