Precision measurement of the Z invisible width with the CMS experiment

A precision measurement of the partial width of the Z boson decay to an invisible final state is reported. Events from proton-proton collisions provided by the Large Hadron Collider at a centre-of-mass energy of 13 TeV are collected by the Compact Muon Solenoid experiment with the invisibly decaying Z bosons inferred from a hadronic recoil. The data collected corresponds to a total integrated luminosity of 35.9 fb−1. The invisible width is measured to be 512+16−15 MeV, consistent with the standard model. This is a competitive result to previous measurements performed at the Large Electron Positron collider. The measurement is systematically dominated by uncertainties associated with the measurement of the energy scale of the recoiling hadronic system.Open Acces

Precision measurement of the Z invisible width with the CMS experiment

A precision measurement of the partial width of the Z boson decay to an invisible final state is reported. Events from proton-proton collisions provided by the Large Hadron Collider at a centre-of-mass energy of 13 TeV are collected by the Compact Muon Solenoid experiment with the invisibly decaying Z bosons inferred from a hadronic recoil. The data collected corresponds to a total integrated luminosity of 35.9 fb${}^{-1}$ . The invisible width is measured to be 512 $_{-15}^{+16}$ MeV, consistent with the standard model. This is a competitive result to previous measurements performed at the Large Electron Positron collider. The measurement is systematically dominated by uncertainties associated with the measurement of the energy scale of the recoiling hadronic system

The CMS Level-1 Calorimeter Trigger for LHC Run II

Results from the completed Phase 1 Upgrade of the Compact Muon Solenoid (CMS) Level-1 Calorimeter Trigger are presented. The upgrade was completed in two stages, with the first running in 2015 for proton and Heavy Ion collisions and the final stage for 2016 data taking. The Level-1 trigger has been fully commissioned and has been used by CMS to collect over 43 fb-1 of data since the start of the Large Hadron Collider (LHC) Run II. The new trigger has been designed to improve the performance at high luminosity and large number of simultaneous inelastic collisions per crossing (pile-up). For this purpose it uses a novel design, the Time Multiplexed Trigger (TMT), which enables the data from an event to be processed by a single trigger processor at full granularity over several bunch crossings. The TMT design is a modular design based on the uTCA standard. The trigger processors are instrumented with Xilinx Virtex-7 690 FPGAs and 10 Gbps optical links. The TMT architecture is flexible and the number of trigger processors can be expanded according to the physics needs of CMS. Sophisticated and innovative algorithms are now the core of the first decision layer of the experiment. The system has been able to adapt to the outstanding performance of the LHC, which ran with an instantaneous luminosity well above design. The performance of the system for single physics objects are presented along with the optimizations foreseen to maintain the thresholds for the harsher conditions expected during the LHC Run II and Run III periods