The Compact Muon Solenoid (CMS) is a general purpose experiment to explore the physics of the TeV scale in proton-proton collisions provided by the CERN LHC. Muons constitute an important signature of new physics and their detection, triggering, reconstruction and identification is guaranteed by various sub-detectors using different detection systems. During Run 2 and Run 3, the higher instantaneous luminosity leads to a substantial background in the muon system. The analysis is based on data collected in pp collisions at 13.6 TeV (Run 2) and 13.6 TeV (Run 3) in 2018 and 2023-2024, respectively, with instantaneous luminosities up to 2.2x1034 cm-2 s-1. A thorough understanding of background rates provides the base for the upgrade of the muon detectors for the High-Luminosity LHC, where the instantaneous luminosity will reach 5-7.5x1034 cm-2 s-1, resulting in 140-200 simultaneous proton-proton collisions, i.e. collisions occurring within one single bunch time window.
The current operation of the Resistive Plate Chamber (RPC) system within the CMS experiment involves approximately 95% tetrafluoroethane (C2H2F4, TFE). However, in response to climate change concerns, the European Union has instituted a ban on TFE owing to its elevated Global Warming Potential, resulting in an associated increase in market prices. In this framework, shared endeavors within the RPC EcoGas@GIF++ Collaboration, have been dedicated to investigating novel ecological gaseous mixtures based on tetrafluoropropene (C3H2F4, HFO-1234ze) to ensure the sustainable functionality of RPCs. This contribution will delve into the performance outcomes derived from improved RPC gas gaps operating on HFO/CO2-based mixtures as ecologically viable alternatives, particularly in anticipation of the High Luminosity LHC phase (HL-LHC).
The results of a search for a standard model-like Higgs boson decaying into two photons in the mass range between 70 and 110 GeV are presented. The analysis uses the data set collected by the CMS experiment in proton-proton collisions at root s = 13 TeV corresponding to integrated luminosities of 36.3 fb(-1), 41.5 fb(-1) and 54.4 fb(-1) during the 2016, 2017, and 2018 LHC running periods, respectively. No significant excess over the background expectation is observed and 95% cofidence level upper limits are set on the product of the cross section and branching fraction for decays of an additional Higgs boson into two photons. The maximum deviation with respect to the background is seen for a mass hypothesis of 95.4 GeV with a local (global) significance of 2.9 (1.3) standard deviations. The observed upper limit ranges from 15 to 73 fb.
The assessment of research performance is widely seen as a vital tool in upholding the highest standards of quality, with selection and competition believed to drive progress. Academic institutions need to take critical decisions on hiring and promotion, while facing external pressure by also being subject to research assessment1, 2, 3-4. Here we present an outlook on research assessment for career progression with specific focus on promotion to full professorship, based on 314 policies from 190 academic institutions and 218 policies from 58 government agencies, covering 32 countries in the Global North and 89 countries in the Global South. We investigated how frequently various promotion criteria are mentioned and carried out a statistical analysis to infer commonalities and differences across policies. Although quantitative methods of assessment remain popular, in agreement with what is found in more geographically restricted studies5, 6, 7, 8-9, they are not omnipresent. We find differences between the Global North and the Global South as well as between institutional and national policies, but less so between disciplines. A preference for bibliometric indicators is more marked in upper-middle-income countries. Although we see some variation, many promotion policies are based on the assumption of specific career paths that become normative rather than embracing diversity. In turn, this restricts opportunities for researchers. These results challenge current practice and have strategic implications for researchers, research managers and national governments.
Measurements at root s = 13.6 TeV of the opposite-sign W boson pair production cross section in proton-proton collisions are presented. The data used in this study were collected with the CMS detector at the CERN LHC in 2022, and correspond to an integrated luminosity of 34.8 fb(-1). Events are selected by requiring one electron and one muon of opposite charge. A maximum likelihood fit is performed on signal- and background-enriched data categories dfined by the flavor and charge of the leptons, the number of jets, and number of jets originating from b quarks. The overall sensitivity is significantly better than that of previous results with a similar integrated luminosity. The improvement comes from a more rfined control of experimental uncertainties and an improved fit strategy. An inclusive W+W- production cross section of 125.7 +/- 5.6 pb is measured, in agreement with standard model predictions. Cross sections are also reported in a fiducial region close to that of the detector acceptance, both inclusively and differentially, as a function of the jet multiplicity in the event. For the first time in proton-proton collisions, WWevents with zero, one, and at least two jets are studied simultaneously and compared with recent theoretical predictions.
