J. Strauss

Electron pair production at the CERN ISR

Abstract The electron pair production cross section from pp collisions at c.m. energies √s = 52 and 63 GeV has been measured for masses above 1.4 GeV/c2. The J/ψ is dominant in this mass range and its production properties have been studied. An estimate of the ψ′ production cross section is given. Limits for ϒ → e+e− and χ → J ψγ productions are presented. The behaviour of the continuum cross section as a function of mass is compared to current theoretical estimates.

Searches for third-generation squark production in fully hadronic final states in proton-proton collisions at √s=8 TeV

A bstractSearches for third-generation squarks in fully hadronic final states are presented using data samples corresponding to integrated luminosities of 19.4 or 19.7 fb−1, collected at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC. Three mutually exclusive searches are presented, each optimized for a different decay topology. They include a multijet search requiring one fully reconstructed top quark, a dijet search requiring one or two jets originating from b quarks, and a monojet search. No excesses above the standard model expectations are seen, and limits are set on top and bottom squark production in the context of simplified models of supersymmetry. Searches for third-generation squarks in fully hadronic final states are presented using data samples corresponding to integrated luminosities of 19.4 or 19.7 fb-1, collected at a centre-of-mass energy of 8 CMS.TeV with the CMS detector at the LHC. Three mutually exclusive searches are presented, each optimized for a different decay topology. They include a multijet search requiring one fully reconstructed top quark, a dijet search requiring one or two jets originating from b quarks, and a monojet search. No excesses above the standard model expectations are seen, and limits are set on top and bottom squark production in the context of simplified models of supersymmetry.

Inclusive π0 production from high-energy p-p collisions at very large transverse momenta

Abstract We report on measurements of inclusive π 0 production at c.m. energies of 53 and 63 GeV, θ ≅90°, from p-p collisions at the CERN ISR. In the range 0.2 x t Ed 3 σ d p 3 ∝p − (6.6±0.8) t (1−x t ) (9.6±1.0) .

Search for the production of dark matter in association with top-quark pairs in the single-lepton final state in proton-proton collisions at sqrt(s) = 8 TeV

A bstractA search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s=8

Muon - Electron Events in High-energy Proton Proton Collisions

\sqrt{s}=8

On the production of charmed mesons in high-energy proton-proton collisions

TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb−1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.

Production of high transverse momentum low-mass electron-positron pairs in high-energy pp collisions

The spectra of charged particles produced within the pseudorapidity window |η| < 1 at √ sNN = 5.02 TeV are measured using 404 μb−1 of PbPb and 27.4 pb−1 of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < pT < 400 GeV in pp and 0.7 < pT < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, RAA, is measured in bins of collision centrality. The RAA in the 5% most central collisions shows a maximal suppression by a factor of 7–8 in the pT region of 6–9 GeV. This dip is followed by an increase, which continues up to the highest pT measured, and approaches unity in the vicinity of pT = 200 GeV. The RAA is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS Collaboration to construct the pPb nuclear modification factor, RpA, up to 120 GeV. For pT > 20 GeV, RpA exhibits weak momentum dependence and shows a moderate enhancement above unity. Published in the Journal of High Energy Physics as doi:10.1007/JHEP04(2017)039. c

Measurement of the transverse momentum spectra of weak vector bosons produced in proton-proton collisions at √s=8 TeV

Abstract We have searched for events in proton-proton collisions, at the CERN Intersecting Storage Rings, which contain a muon and an electron of opposite sign. Such events cannot come from the decay of a single vector meson or from the Drell-Yan process, but can comee from the semileptonic decays of a pair of charmed mesons. We find a signal of 32 ± 16 events. Assumming that the signal is caused by charmed meson pairs, and using a model for the p T and p L distribution of such pairs, we estimate the total inclusive charm production cross section in proton-proton collisions to be (70 ± 36) μb.