Search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks in proton-proton collisions at root s=13TeV

A search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks is performed in proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 35.9 fb(-1). The signal is characterized by a large missing transverse momentum recoiling against a bottom quark-antiquark system that has a large Lorentz boost. The number of events observed in the data is consistent with the standard model background prediction. Results are interpreted in terms of limits both on parameters of the type-2 two-Higgs doublet model extended by an additional light pseudoscalar boson a (2HDM+a) and on parameters of a baryonic Z simplified model. The 2HDM+a model is tested experimentally for the first time. For the baryonic Z model, the presented results constitute the most stringent constraints to date.Peer reviewe

A Deep Neural Network for Simultaneous Estimation of b Jet Energy and Resolution

We describe a method to obtain point and dispersion estimates for the energies of jets arising from b quarks produced in proton-proton collisions at an energy of s = 13 TeV at the CERN LHC. The algorithm is trained on a large sample of simulated b jets and validated on data recorded by the CMS detector in 2017 corresponding to an integrated luminosity of 41 fb - 1 . A multivariate regression algorithm based on a deep feed-forward neural network employs jet composition and shape information, and the properties of reconstructed secondary vertices associated with the jet. The results of the algorithm are used to improve the sensitivity of analyses that make use of b jets in the final state, such as the observation of Higgs boson decay to b b ¯

Search for low-mass dilepton resonances in Higgs boson decays to four-lepton final states in proton–proton collisions at √s=13TeV

Data Availability: This manuscript has no associated data or the data will not be deposited. [Authors’ comment: For CMS Release and preservation of data used by the CMS Collaboration as the basis for publications is guided by the CMS policy as stated in “CMS data preservation, re-use and open access policy” (https://cms-docdb.cern.ch/cgi-bin/PublicDocDB/RetrieveFile?docid=6032&filename=CMSDataPolicyV1.2.pdf&version=2).]Copyright © CERN for the benefit of the CMS collaboration 2022. A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a Z boson. The search uses proton–proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137fb−1, at a center-of-mass energy s√=13TeV. No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported.SCOAP3

Search for dark matter produced in association with a leptonically decaying Z boson in proton–proton collisions at s√=13TeV

A search for dark matter particles is performed using events with a Z boson candidate and large missing transverse momentum. The analysis is based on proton–proton collision data at a center-of-mass energy of 13TeV, collected by the CMS experiment at the LHC in 2016–2018, corresponding to an integrated luminosity of 137fb−1. The search uses the decay channels Z→ee and Z→μμ. No significant excess of events is observed over the background expected from the standard model. Limits are set on dark matter particle production in the context of simplified models with vector, axial-vector, scalar, and pseudoscalar mediators, as well as on a two-Higgs-doublet model with an additional pseudoscalar mediator. In addition, limits are provided for spin-dependent and spin-independent scattering cross sections and are compared to those from direct-detection experiments. The results are also interpreted in the context of models of invisible Higgs boson decays, unparticles, and large extra dimensions.SCOAP

Measurements of pp → ZZ production cross sections and constraints on anomalous triple gauge couplings at √ = 13 TeV

© 2021 The CMS Collaboration. The production of Z boson pairs in proton–proton (pp) collisions, pp → (Z/∗)(Z/∗) → 2ℓ2ℓ′, where ℓ,ℓ′ = e or μ, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137fb−1, collected during 2016–2018. The ZZ production cross section, tot(pp → ZZ) = 17.4 ± 0.3 (stat) ± 0.5 (syst) ± 0.4 (Theo) ± 0.3 (lumi) pb, measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region 60 < ℓ+ℓ− < 120 GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ couplings.SCOAP

Support vector machine based online coal identification through advanced flame monitoring

This paper presents a new on-line coal identification system based on support vector machine (SVM) to achieve on-line coal identification under variable combustion conditions. Four different coals were burnt in a 0.3 MW coal combustion furnace with different coal feed rates, total air flow rates and flow rate ratios of primary air and secondary air. The flame monitoring system was installed at the exit of the burner to acquire the coal flame images and light intensity signals. Spatial and temporal flame features were extracted for coal identification. The averaged prediction accuracy is 99.1%. The mean value of the infrared signal has the most significant influence on prediction accuracy. For “unstudied” operation cases, the prediction accuracy is 94.7%

Numerical modeling of the iron ore sintering process

Iron ore sintering involves the movement of a flame front down a particulate bed, and a series of physico-chemical reactions over a large temperature range. In the literature simple and more sophisticated iron ore sintering models have been reported. In this paper a more comprehensive numerical model which incorporates most of the significant processes and heat transfer modes proposed in earlier models is given. Therefore, sub-models are available to describe the relationship between airflow rate through the bed and flame front speed, the evaporation and condensation of water ahead of the front, the calcination of fluxes nearer to the front, the reactions that occur in the front and cooling of the bed with the departure of the front. Improvements were made to several areas – such as coke combustion, and the melting and solidification processes – to more accurately quantify the phenomena involved. More recent progress in understanding the fundamentals of sintering from BHP Billiton studies have also been incorporated into the model. To date, twelve sinter pot tests have been used for validation studies. Reasonably good agreement was obtained between predicted and measured results – in areas such as bed temperature profiles and waste gas temperature and compositions. Work is continuing to further improve the model, and broaden the validation work to include other bed temperature profile parameters

Model predictions of important bed and gas properties during iron ore sintering

A new numerical iron ore sintering model was developed recently. It takes into account most of the significant physico-chemical processes in sintering. In this study results from the model are compared with experimental results from twenty five sinter pot tests. Results indicate that the model can simulate the iron ore sintering process, as reasonable correlations between predicted and measured results were obtained in many areas. The good comparisons also indicate that the key sub-models, which have significant effects on results, viz., coke combustion, fluxes calcination, drying and condensation as well as heat and mass transfer, describe the sub-processes well. The phenomena of steady-state waste gas composition (SSWGC) and steady-state waste gas temperature (SSWGT) were simulated and analyzed by the model. A total of nine important input variables were identified and their influence on sintering time and three critical parameters which determine heat transfer during sintering were considered in the sensitivity studies. Results showed that bed bulk density, solid and gas thermal capacities, coke level and diameter and post-ignition airflow rate have the greatest influences on sintering time and the temperature profile parameters. This paper also gives suggestions on how the model can be improved