R. Frühwirth

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.

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

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

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

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.

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

The inelastic hadronic cross section in proton-lead collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is measured with the CMS detector at the LHC. The data sample, corresponding to an integrated luminosity of L = 12.6± 0.4 nb−1, has been collected with an unbiased trigger for inclusive particle production. The cross section is obtained from the measured number of proton-lead collisions with hadronic activity produced in the pseudorapidity ranges 3 < η < 5 and/or −5 < η < −3, corrected for photon-induced contributions, experimental acceptance, and other instrumental effects. The inelastic cross section is measured to be σinel(pPb) = 2061± 3 (stat)± 34 (syst)± 72 (lumi) mb. Various Monte Carlo generators, commonly used in heavy ion and cosmic ray physics, are found to reproduce the data within uncertainties. The value of σinel(pPb) is compatible with that expected from the proton-proton cross section at 5.02 TeV scaled up within a simple Glauber approach to account for multiple scatterings in the lead nucleus, indicating that further net nuclear corrections are small. Published in Physics Letters B as doi:10.1016/j.physletb.2016.06.027. c