Publications by authors named "T Madlener"

101 Publications

Observation of Forward Neutron Multiplicity Dependence of Dimuon Acoplanarity in Ultraperipheral Pb-Pb Collisions at sqrt[s_{NN}]=5.02  TeV.

Phys Rev Lett 2021 Sep;127(12):122001

Universiteit Antwerpen, Antwerpen, Belgium.

The first measurement of the dependence of γγ→μ^{+}μ^{-} production on the multiplicity of neutrons emitted very close to the beam direction in ultraperipheral heavy ion collisions is reported. Data for lead-lead interactions at sqrt[s_{NN}]=5.02  TeV, with an integrated luminosity of approximately 1.5  nb^{-1}, are collected using the CMS detector at the LHC. The azimuthal correlations between the two muons in the invariant mass region 88.3. The back-to-back correlation structure from leading-order photon-photon scattering is found to be significantly broader for events with a larger number of emitted neutrons from each nucleus, corresponding to interactions with a smaller impact parameter. This observation provides a data-driven demonstration that the average transverse momentum of photons emitted from relativistic heavy ions has an impact parameter dependence. These results provide new constraints on models of photon-induced interactions in ultraperipheral collisions. They also provide a baseline to search for possible final-state effects on lepton pairs caused by traversing a quark-gluon plasma produced in hadronic heavy ion collisions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1103/PhysRevLett.127.122001DOI Listing
September 2021

Constraints on the Initial State of Pb-Pb Collisions via Measurements of Z-Boson Yields and Azimuthal Anisotropy at sqrt[s_{NN}]=5.02  TeV.

Phys Rev Lett 2021 Sep;127(10):102002

Universiteit Antwerpen, Antwerpen, Belgium.

The CMS experiment at the LHC has measured the differential cross sections of Z bosons decaying to pairs of leptons, as functions of transverse momentum and rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02  TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is compatible with zero, showing that Z bosons do not experience significant final-state interactions in the medium produced in the collision. Yields of Z bosons are compared to Glauber model predictions and are found to deviate from these expectations in peripheral collisions, indicating the presence of initial collision geometry and centrality selection effects. The precision of the measurement allows, for the first time, for a data-driven determination of the nucleon-nucleon integrated luminosity as a function of lead-lead centrality, thereby eliminating the need for its estimation based on a Glauber model.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1103/PhysRevLett.127.102002DOI Listing
September 2021

Measurement of the Wγ Production Cross Section in Proton-Proton Collisions at sqrt[s]=13  TeV and Constraints on Effective Field Theory Coefficients.

Phys Rev Lett 2021 Jun;126(25):252002

Universiteit Antwerpen, Antwerpen, Belgium.

A fiducial cross section for Wγ production in proton-proton collisions is measured at a center-of-mass energy of 13 TeV in 137  fb^{-1} of data collected using the CMS detector at the LHC. The W→eν and μν decay modes are used in a maximum-likelihood fit to the lepton-photon invariant mass distribution to extract the combined cross section. The measured cross section is compared with theoretical expectations at next-to-leading order in quantum chromodynamics. In addition, 95% confidence level intervals are reported for anomalous triple-gauge couplings within the framework of effective field theory.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1103/PhysRevLett.126.252002DOI Listing
June 2021

Observation of a New Excited Beauty Strange Baryon Decaying to Ξ_{b}^{-}π^{+}π^{-}.

Phys Rev Lett 2021 Jun;126(25):252003

Universiteit Antwerpen, Antwerpen, Belgium.

The Ξ_{b}^{-}π^{+}π^{-} invariant mass spectrum is investigated with an event sample of proton-proton collisions at sqrt[s]=13  TeV, collected by the CMS experiment at the LHC in 2016-2018 and corresponding to an integrated luminosity of 140  fb^{-1}. The ground state Ξ_{b}^{-} is reconstructed via its decays to J/ψΞ^{-} and J/ψΛK^{-}. A narrow resonance, labeled Ξ_{b}(6100)^{-}, is observed at a Ξ_{b}^{-}π^{+}π^{-} invariant mass of 6100.3±0.2(stat)±0.1(syst)±0.6(Ξ_{b}^{-})  MeV, where the last uncertainty reflects the precision of the Ξ_{b}^{-} baryon mass. The upper limit on the Ξ_{b}(6100)^{-} natural width is determined to be 1.9  MeV at 95% confidence level. The low Ξ_{b}(6100)^{-} signal yield observed in data does not allow a measurement of the quantum numbers of the new state. However, following analogies with the established excited Ξ_{c} baryon states, the new Ξ_{b}(6100)^{-} resonance and its decay sequence are consistent with the orbitally excited Ξ_{b}^{-} baryon, with spin and parity quantum numbers J^{P}=3/2^{-}.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1103/PhysRevLett.126.252003DOI Listing
June 2021

Measurements of production cross sections and constraints on anomalous triple gauge couplings at .

Eur Phys J C Part Fields 2021 1;81(3):200. Epub 2021 Mar 1.

Universiteit Antwerpen, Antwerpen, Belgium.

The production of Z boson pairs in proton-proton ( ) collisions, , where or , is studied at a center-of-mass energy of 13 with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137 , collected during 2016-2018. The production cross section, , measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous and couplings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1140/epjc/s10052-020-08817-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7921081PMC
March 2021
-->