A search for pair production of third-generation scalar leptoquarks decaying to top quark and τ lepton pairs is presented using proton-proton collision data at a center-ofmass energy of √ s = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb −1 . The search is performed using events that contain an electron or a muon, a hadronically decaying τ lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a τ lepton, the existence of pair produced, charge −1/3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a τ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling λ 333 .
Processes τ → lγ, τ → lll with l = e, µ and µ(τ ) → e(µ)γ are evaluated in the framework of a model based on the extended symmetry gauge SU (3) c ⊗ SU (3) L ⊗ U (1) Y with a leptonic sector consistent of five triplets. Lepton flavor violating processes are allowed at tree level in this model through the new Z gauge boson. We obtained bounds for the mixing angles in the leptonic sector of the model, considering the experimental measurements of the processes from the BELLE and the BABAR collaborations.
We present the second in a series of studies into the forward tracking system for a future linear e + e − collider with a center-of-mass energy in the range from 250 GeV to 3 TeV. In this note a number of specific challenges are investigated, that have caused a degradation of the tracking and vertexing performance in the forward region in previous experiments. We perform a quantitative analysis of the dependence of the tracking performance on detector design parameters and identify several ways to mitigate the performance loss for charged particles emitted at shallow angle.
A: Results obtained with 3D columnar pixel sensors bump-bonded to the RD53A prototype readout chip are reported. The interconnected modules have been tested in a hadron beam before and after irradiation to a fluence of about 1×10 16 neq cm −2 (1 MeV equivalent neutrons). All presented results are part of the CMS R&D activities in view of the pixel detector upgrade for the High Luminosity phase of the LHC at CERN (HL-LHC). A preliminary analysis of the collected data shows hit detection efficiencies around 97% measured after proton irradiation.
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