2,419 research outputs found
Sensitivity to new physics in final states with multiple gauge and Higgs bosons
No full textInternational audienceWe analyse the sensitivity to beyond-the-Standard-Model effects of hadron-collider processes involving the interaction of two electroweak and two Higgs bosons, VVHH, with V being either a W or a Z boson. We examine current experimental results by the CMS collaboration in the context of a dimension-8 extension of the Standard Model in an effective-field-theory formalism. We show that constraints from vector-boson-fusion Higgs-pair production on operators that modify the Standard Model VVHH interactions are already comparable with or more stringent than those quoted in the analysis of vector-boson-scattering final states. We study the modifications of such constraints when introducing unitarity bounds, and investigate the potential of new experimental final states, such as ZHH associated production. Finally, we show perspectives for the high-luminosity phase of the LHC
Measurement of Higgs boson properties in the four-lepton final state at 13 TeV at CMS
No full textThis paper reports the measurement of Higgs boson properties performed in the four-lepton final state using proton-proton collision data collected by the CMS experiment at CERN in 2016 at a centre-of-mass energy of 13TeV. In particular, the measurement of the signal strength modifier (defined as the ratio of the observed Higgs boson rate in the four-lepton decay channel to the Standard Model expectation) is presented both inclusively and separately for the individual Higgs boson production modes. The measurements of the Higgs boson mass and width are also reported
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textIn the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the articl
Search for non resonant Higgs boson pair production in the four-lepton two-b-jet final state at with the CMS experiment at the LHC
No full textThis thesis presents the search for non-resonant double Higgs boson (HH) production in the final state where one of the two Higgs bosons decays into four leptons (, with denoting either an electron or a muon), while the other decays into a pair of b quarks (), which hadronise in jets. The analysis is performed exploiting the full dataset collected by the CMS experiment in the LHC Run II in proton-proton collisions at , corresponding to an integrated luminosity of . The analysis presented is the first search for HH production performed in the final state and the first HH analysis in the CMS collaboration to be completed with the full Run II dataset. An upper limit on the HH production cross section times the branching fraction in the final state is set to 30 times the standard model (SM) predictions at 95\% confidence level (CL). Possible modifications of the Higgs boson self coupling are also investigated, and the Higgs boson self coupling modifier is constrained to the range at 95\% CL
Muon detection in electron-positron annihilation for muon collider studies
No full textThe investigation of the energy frontier in physics requires novel concepts for future colliders. The idea of a muon collider is very appealing since it would allow to study particle collisions at up to tens of TeV energy, while offering a cleaner experimental environment with respect to hadronic colliders. One key element in the muon collider design is the low-emittance muon production. Recently, the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the muon pair production close to its kinematic threshold by annihilating 45 GeV positrons with electrons in a low Z material target. In this configuration, muons are emerging from the target with a naturally low-emittance. In this paper we describe the performance of a system, to study this production mechanism, that consists in several segmented absorbers with alternating active layers composed of fast Cherenkov detectors together with a muon identification technique based on this detector. Passive layers were made of tungsten. We collected data corresponding to muon and electron beams produced at the H2 line in the North Area of the European Organization for Nuclear Research (CERN) in September 2018
Positron driven muon source for a muon collider
No full textThe design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. In this paper a layout of a positron driven muon source known as the Low EMittance Muon Accelerator (LEMMA) concept is presented. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven to a multi-target system, to produce muon pairs at threshold. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition (PEDD) on the targets. Muons produced in the multi-target system will then be accumulated before acceleration and injection in the collider. A multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D
Muon detection in electron-positron annihilation for muon collider studies
No full textInternational audienceThe investigation of the energy frontier in physics requires novel concepts for future colliders. The idea of a muon collider is very appealing since it would allow to study particle collisions at up to tens of TeV energy, while offering a cleaner experimental environment with respect to hadronic colliders. One key element in the muon collider design is the low-emittance muon production. Recently, the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the muon pair production close to its kinematic threshold by annihilating 45 GeV positrons with electrons in a low Z material target. In this configuration, muons are emerging from the target with a naturally low-emittance. In this paper we describe the performance of a system, to study this production mechanism, that consists in several segmented absorbers with alternating active layers composed of fast Cherenkov detectors together with a muon identification technique based on this detector. Passive layers were made of tungsten. We collected data corresponding to muon and electron beams produced at the H2 line in the North Area of the European Organization for Nuclear Research (CERN) in September 2018
Publisher Correction: Observation of triple J/ψ meson production in proton-proton collisions
No full textIn the version of this article initially published, the first affiliation—Yerevan Physics Institute, Yerevan, Armenia—was missing from the list of author affiliations and has now been inserted in the HTML and PDF versions of the articl
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