Physics & Astronomy Scholarly Works
https://hdl.handle.net/1808/110
2024-03-28T16:58:19ZMeasurement of the differential tt⎯⎯ production cross section as a function of the jet mass and extraction of the top quark mass in hadronic decays of boosted top quarks
https://hdl.handle.net/1808/34744
Measurement of the differential tt⎯⎯ production cross section as a function of the jet mass and extraction of the top quark mass in hadronic decays of boosted top quarks
CMS Collaboration
A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production (tt⎯⎯) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400GeV. The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138fb−1. The differential tt⎯⎯ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modeling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of 173.06±0.84GeV.
2023-07-03T00:00:00ZCMS PYTHIA 8 colour reconnection tunes based on underlying-event data
https://hdl.handle.net/1808/34742
CMS PYTHIA 8 colour reconnection tunes based on underlying-event data
CMS Collaboration
New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the PYTHIA 8 event generator, are obtained based on the default CMS PYTHIA 8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies √𝑠=7 and 13TeV, and by the CDF experiment at 1.96TeV are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13TeV including measurements of the underlying-event, strange-particle multiplicities, jet substructure observables, jet shapes, and colour flow in top quark pair (tt¯) events. The new tunes are also used to estimate the uncertainty related to colour reconnection modelling in the top quark mass measurement using the decay products of tt¯ events in the semileptonic channel at 13TeV.
2023-07-10T00:00:00ZMetallic and Non-Metallic Plasmonic Nanostructures for LSPR Sensors
https://hdl.handle.net/1808/34731
Metallic and Non-Metallic Plasmonic Nanostructures for LSPR Sensors
Wu, Judy Z.; Ghopry, Samar Ali; Liu, Bo; Shultz, Andrew
Localized surface plasmonic resonance (LSPR) provides a unique scheme for light management and has been demonstrated across a large variety of metallic nanostructures. More recently, non-metallic nanostructures of two-dimensional atomic materials and heterostructures have emerged as a promising, low-cost alternative in order to generate strong LSPR. In this paper, a review of the recent progress made on non-metallic LSPR nanostructures will be provided in comparison with their metallic counterparts. A few applications in optoelectronics and sensors will be highlighted. In addition, the remaining challenges and future perspectives will be discussed.
2023-07-08T00:00:00ZSearch for light Higgs bosons from supersymmetric cascade decays in pp collisions at √𝑠=13TeV
https://hdl.handle.net/1808/34729
Search for light Higgs bosons from supersymmetric cascade decays in pp collisions at √𝑠=13TeV
CMS Collaboration
A search is reported for pairs of light Higgs bosons (H1) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC pp collisions collected with the CMS detector at √𝑠=13TeV and corresponding to an integrated luminosity of 138fb−1 is used. The search targets events where both H1 bosons decay into pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a “singlino” of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like H1 and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the branching fraction of the H1 in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like branching fraction, H1 bosons with masses in the range 40–120GeV arising from the decays of squarks or gluinos with a mass of 1200–2500GeV are excluded at 95% confidence level.
2023-07-06T00:00:00Z