Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Observation of tW production in the single-lepton channel in pp collisions at root s=13 TeV

A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at root s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb(-1) collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant t (t) over bar background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 +/- 4 (stat) +/- 12 (syst) pb, consistent with the standard model.Peer reviewe

Measurement of the top quark mass using events with a single reconstructed top quark in pp collisions at root s=13 TeV

Abstract:A measurement of the top quark mass is performed using a data sample en-riched with single top quark events produced in thetchannel. The study is based on proton-proton collision data, corresponding to an integrated luminosity of 35.9 fb−1, recorded at√s= 13TeV by the CMS experiment at the LHC in 2016. Candidate events are selectedby requiring an isolated high-momentum lepton (muon or electron) and exactly two jets,of which one is identified as originating from a bottom quark. Multivariate discriminantsare designed to separate the signal from the background. Optimized thresholds are placedon the discriminant outputs to obtain an event sample with high signal purity. The topquark mass is found to be172.13+0.76−0.77GeV, where the uncertainty includes both the sta-tistical and systematic components, reaching sub-GeV precision for the first time in thisevent topology. The masses of the top quark and antiquark are also determined separatelyusing the lepton charge in the final state, from which the mass ratio and difference aredetermined to be0.9952+0.0079−0.0104and0.83+1.79−1.35GeV, respectively. The results are consistentwithCPTinvariance

Search for a heavy Higgs boson decaying into two lighter Higgs bosons in the tau tau bb final state at 13 TeV

A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h(S) is presented. The h and h(S) bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137 fb(-1). Mass ranges of 240-3000 GeV for m(H) and 60-2800 GeV for m(hS) are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for m(H) = 240 GeV) to 2.7 fb (for m(H) = 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model.Peer reviewe

Development and firmware implementation of a Machine Learning based hadronic Tau lepton Level-1 Trigger algorithm in CMS for the HL-LHC

The High-Luminosity LHC (HL-LHC) will open an unprecedented window on the weak-scale nature of the universe, providing high-precision measurements of the standard model as well as searches for new physics beyond it. The CMS Collaboration is planning to replace entirely its trigger and data acquisition systems to match this ambitious physics program. Efficiently collecting datasets in Phase-2 will be a challenging task, given the harsh environment of 200 simultaneous proton-proton interactions per HL-LHC bunch crossing. The already challenging implementation of an efficient tau lepton trigger will become, in such conditions, an even more crucial and harder task; especially interesting will be the case of hadronically decaying tau. To this end, the highly upgraded capabilities of the Phase 2 Level-1 triggering system can be exploited to design new complex machine learning based algorithms that are not yet implementable in the current Phase-1 system. Moreover, the foreseen high-granularity endcap calorimeter and the astonishing amount of information it will provide play a key role in the design of novel tau lepton triggering methods. In these proceedings, the development of a Level-1 trigger algorithm, with consistent barrel and endcap treatment, for hadronically decaying tau based on the calorimetric information from the ECAL, HCAL, and HGCAL detectors will be presented: the TauMinator. A completely new and innovative design for a Level-1 trigger algorithm based on convolutional neural networks will be shown alongside its preliminary FPGA firmware implementation. The Level-1 trigger latency and resource availability constraints will also be discussed, and their role in the algorithm design will be highlighted

Overview of the HL-LHC Upgrade for the CMS Level-1 Trigger

International audienceThe High-Luminosity LHC (HL-LHC) will open an unprecedented window on the weak-scale nature of the universe, providing high-precision measurements of the standard model as well as searches for new physics beyond the standard model. Such precision measurements and searches require information-rich datasets with statistical power that matches the high luminosity provided by the Phase-2 upgrade of the LHC. Efficiently collecting those datasets will be a challenging task, given the harsh environment of 200 simultaneous proton-proton interactions per HL-LHC bunch crossing. For this purpose, CMS is designing an efficient data-processing hardware trigger (Level-1) that will include tracking information and high-granularity calorimeter information. Trigger data analysis will be performed through sophisticated algorithms such as particle flow reconstruction, including the widespread use of Machine Learning. The current conceptual system design is expected to take full benefit of advances in FPGA and link technologies over the coming years, providing a high-performance, low-latency computing platform for large throughput and sophisticated data correlation across diverse sources. The expected impact on the physics reach of the experiment will be summarized in these proceedings and illustrated with selected benchmark channels

Development and firmware implementation of a Machine Learning based hadronic Tau lepton Level-1 Trigger algorithm in CMS for the HL-LHC

The High-Luminosity LHC (HL-LHC) will open an unprecedented window on the weak-scale nature of the universe, providing high-precision measurements of the standard model as well as searches for new physics beyond it. The CMS Collaboration is planning to replace entirely its trigger and data acquisition systems to match this ambitious physics program. Efficiently collecting datasets in Phase-2 will be a challenging task, given the harsh environment of 200 simultaneous proton-proton interactions per HL-LHC bunch crossing. The already challenging implementation of an efficient tau lepton trigger will become, in such conditions, an even more crucial and harder task; especially interesting will be the case of hadronically decaying tau. To this end, the highly upgraded capabilities of the Phase 2 Level-1 triggering system can be exploited to design new complex machine learning based algorithms that are not yet implementable in the current Phase-1 system. Moreover, the foreseen high-granularity endcap calorimeter and the astonishing amount of information it will provide play a key role in the design of novel tau lepton triggering methods. In these proceedings, the development of a Level-1 trigger algorithm, with consistent barrel and endcap treatment, for hadronically decaying tau based on the calorimetric information from the ECAL, HCAL, and HGCAL detectors will be presented: the TauMinator. A completely new and innovative design for a Level-1 trigger algorithm based on convolutional neural networks will be shown alongside its preliminary FPGA firmware implementation. The Level-1 trigger latency and resource availability constraints will also be discussed, and their role in the algorithm design will be highlighted

Development of a L1 tau lepton trigger algorithm for the HL-LHC using the CMS high-granularity calorimeter information

International audienceThe High-Luminosity LHC will open an unprecedented window on the weak-scale nature of the universe, providing high-precision measurements of the Standard Model (SM) as well as searches for new physics beyond the SM. The CMS Collaboration is planning to replace entirely its trigger and data acquisition systems to match this ambitious physics program. Efficiently collecting datasets in Phase 2 will be a challenging task, given the harsh environment of 200 proton-proton interactions per LHC bunch crossing. The already challenging implementation of an efficient tau lepton trigger will become, in such conditions, an even crucial and harder task; especially interesting will be the case of hadronically decaying taus. To this end, the foreseen high-granularity endcap calorimeter (HGCAL), and the astonishing amount of information it will provide, play a key role in the design of the new online Level-1 (L1) triggering system. In these proceedings, the development of a L1 trigger for hadronically decaying taus based on the sole information from the HGCAL detector will be presented. Some novel ideas for a L1 trigger based on machine learning techniques that can be implemented in FPGA firmware will be presented, as well as the expected performance of the new trigger algorithm based on simulated collision data of the HL-LHC