Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

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

CMS endcap upgrade: Quality Control of scintillator tiles of the High Granularity Calorimeter

High Granularity Calorimeter (HGCAL) is the Phase II upgrade for the CMS experiment. It is being constructed to replace the existing CMS endcap calorimeters in order to fulfill criteria placed on detectors for the upcoming HL-LHC era: radiation hardness, mitigation of pile-up and improved performance. Developed technologies and their implementation will allow for the HGCAL to be used to perform quality measurements up to expected integrated luminosity of 3000 fb-1 and beyond. To ensure that, said technologies are undergoing quality control (QC) during production. Methods for Scintillator tile QC are discussed

Quality control of the pre-series scintillator tiles of the High Granularity Calorimeter upgrade of the CMS experiment

As the High Luminosity era of LHC approaches, it is important to finalise production techniques for the components of the upgrades of the collider experiments and CMS is no exception. The CMS endcap calorimeters are getting a high granularity upgrade (HGCAL), which promises to improve energy resolution by reducing background via pileup rejection. This is done through use of both intrinsic timing capabilities of the sensors and front-end electronics design as well as unprecedented transverse and longitudinal segmentation. HGCAL consists of electromagnetic and hadronic compartments, the latter of which is divided into two by the different technologies used in its construction. One of them, SiPM-on-tile, will make up ~250 000 channels: scintillator tiles optically coupled to SiPMs soldered onto a PCB with readout electronics. All of such channels will need to withstand harsh radiation conditions of HL-LHC to be able to continue with physics searches until the end of life (integrated luminosity ~ 3000 fb-1) and even beyond. Assurance of that is tackled by the Tile Assembly Center (TAC) at DESY performing quality control (QC) checks for all components of the SiPM-on-tile section of the HGCAL. Results of QC of scintillator tiles are discussed. Tiles under investigation are pre-series tiles the study of which aids the finalising of the production techniques. This part is essential for start and ease of the final production phase

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

In this paper we present a synthetic approach to six new D–π–A–D conjugated chromophores containing the N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment. Such readily functionalizable heterocycle as carbazole was used as a main starting compound for their preparation. The investigation of the optical properties has shown that the positive solvatochromism is inherent to the chromophores containing an electron-withdrawing prop-2-en-1-one fragment, while the compounds containing a 2-aminopyrimidine moiety exhibit both positive and negative solvatochromism. The fluorescence quantum yields were experimentally determined for some of the synthesized chromophores; e.g., 1-(5-arylthiophen-2-yl)ethanones quantum yields were found to lie in an interval of 60–80%. Electrochemical oxidation of the synthesized chromophores has resulted in the formation of colored thin oligomeric films that became possible due to the presence of carbazole or pyrrole fragments with free electron-rich positions

A Synthetic Analog of the Mineral Ivanyukite: Sorption Behavior to Lead Cations

The production of electrolytic nickel includes the stage of leaching of captured firing nickel matte dust. The solutions formed during this process contain considerable amounts of Pb, which is difficult to extraction due to its low concentration upon the high-salt background. The sorption of lead from model solutions with various compositions by synthetic and natural titanosilicate sorbents (synthetic ivanyukite-Na-T (SIV), ivanyukite-Na-T, and AM-4) have been investigated. The maximal sorption capacity of Pb is up to 400 mg/g and was demonstrated by synthetic ivanyukite In solutions with the high content of Cl− (20 g/L), extraction was observed only with a high amount of Na (150 g/L). Molecular mechanisms and kinetics of lead incorporation into ivanyukite were studied by the combination of single-crystal and powder X-ray diffraction, microprobe analysis, and Raman spectroscopy. Incorporation of lead into natural ivanyukite-Na-T with the R3m symmetry by the substitution 2Na+ + 2O2− ↔ Pb2+ + □ + 2OH− leds to its transformation into the cubic P−43m Pb-exchanged form with the empirical formulae Pb1.26[Ti4O2.52(OH)1.48(SiO4)3]·3.32(H2O)