50 research outputs found

    Comparison of efficacy and safety of XEN45 implant versus trabeculectomy in Asian eyes

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    Combined phacoemulsification and trabeculectomy is able to achieve greater reduction in intraocular pressure (IOP), higher rates of complete surgical success and fewer postoperative manipulations and visits compared with combined phacoemulsification and Xen implantation in glaucomatous eyes

    Comparison of efficacy of combined phacoemulsification and iStent inject versus combined phacoemulsification and hydrus microstent

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    Aim: This study aims to compare the efficacy and safety of combined phacoemulsification with iStent inject (Phaco-iStent) and Hydrus microstent (Phaco-Hydrus). Methods: This was a retrospective comparative study of patients who underwent Phaco-iStent from April 2019 to August 2020 and Phaco-Hydrus from August 2019 to December 2020 at a tertiary eye centre in Singapore. Sixty-nine Phaco-iStent eyes and 49 Phaco-Hydrus eyes were included in this study. Complete surgical success was defined as freedom from second glaucoma surgery, Intraocular pressure (IOP) of 18 mmHg or less, and discontinuation of all antiglaucoma medications. Results: At 12 months, both Phaco-iStent and Phaco-Hydrus groups had comparable surgical success rate (68.1% vs 51%, p=0.061), reduction in antiglaucoma medication use (− 1.3 ± 0.1 vs − 1.4 ± 0.10, p=0.880) and intraocular pressure reduction (− 1.1 ± 0.5 mmHg vs – 1.6 ± 0.9 mmHg, p=0.323). Overall intraoperative and postoperative complications rate were similar in both groups, though hyphema was more commonly seen in early postoperative period in the Phaco-Hydrus compared to the Phaco-iStent group (8% vs 0%, p=0.028), with majority of cases resolving without any need for surgical intervention. Device obstruction was also more common in the Phaco-Hydrus group compared to the Phaco-iStent group (14% vs 4.3%, p=0.04). Conclusion: Phaco-iStent and Phaco-Hydrus have similar surgical efficacy and safety profiles at 12 months.Published versio

    The CMS Statistical Analysis and Combination Tool: COMBINE

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    International audienceThis paper describes the COMBINE software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run COMBINE and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of COMBINE. However, the online documentation referenced within this paper provides an up-to-date and complete user guide

    Dark sector searches with the CMS experiment

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    Astrophysical observations provide compelling evidence for gravitationally interacting dark matter in the universe that cannot be explained by the standard model of particle physics. The extraordinary amount of data from the CERN LHC presents a unique opportunity to shed light on the nature of dark matter at unprecedented collision energies. This Report comprehensively reviews the most recent searches with the CMS experiment for particles and interactions belonging to a dark sector and for dark-sector mediators. Models with invisible massive particles are probed by searches for signatures of missing transverse momentum recoiling against visible standard model particles. Searches for mediators are also conducted via fully visible final states. The results of these searches are compared with those obtained from direct-detection experiments. Searches for alternative scenarios predicting more complex dark sectors with multiple new particles and new forces are also presented. Many of these models include long-lived particles, which could manifest themselves with striking unconventional signatures with relatively small amounts of background. Searches for such particles are discussed and their impact on dark-sector scenarios is evaluated. Many results and interpretations have been newly obtained for this Report.Astrophysical observations provide compelling evidence for gravitationally interacting dark matter in the universe that cannot be explained by the standard model of particle physics. The extraordinary amount of data from the CERN LHC presents a unique opportunity to shed light on the nature of dark matter at unprecedented collision energies. This Report comprehensively reviews the most recent searches with the CMS experiment for particles and interactions belonging to a dark sector and for dark-sector mediators. Models with invisible massive particles are probed by searches for signatures of missing transverse momentum recoiling against visible standard model particles. Searches for mediators are also conducted via fully visible final states. The results of these searches are compared with those obtained from direct-detection experiments. Searches for alternative scenarios predicting more complex dark sectors with multiple new particles and new forces are also presented. Many of these models include long-lived particles, which could manifest themselves with striking unconventional signatures with relatively small amounts of background. Searches for such particles are discussed and their impact on dark-sector scenarios is evaluated. Many results and interpretations have been newly obtained for this Report

    Observation of the J/ψ\psi \to μ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb1{-1}. Normalizing to the J/ψ\psi\toμ+μ\mu^+\mu^- decay mode leads to a branching fraction [10.12.7+3.3^{+3.3}_{-2.7} (stat) ±\pm 0.4 (syst) ]×\times 107^{-7}, a value that is consistent with the standard model prediction

    Enriching the physics program of the CMS experiment via data scouting and data parking

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    International audienceSpecialized data-taking and data-processing techniques were introduced by the CMS experiment in Run 1 of the CERN LHC to enhance the sensitivity of searches for new physics and the precision of standard model measurements. These techniques, termed data scouting and data parking, extend the data-taking capabilities of CMS beyond the original design specifications. The novel data-scouting strategy trades complete event information for higher event rates, while keeping the data bandwidth within limits. Data parking involves storing a large amount of raw detector data collected by algorithms with low trigger thresholds to be processed when sufficient computational power is available to handle such data. The research program of the CMS Collaboration is greatly expanded with these techniques. The implementation, performance, and physics results obtained with data scouting and data parking in CMS over the last decade are discussed in this Report, along with new developments aimed at further improving low-mass physics sensitivity over the next years of data taking

    Observation of the J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb1{-1}. Normalizing to the J/ψ\psi\toμ+μ\mu^+\mu^- decay mode leads to a branching fraction [10.12.7+3.3^{+3.3}_{-2.7} (stat) ±\pm 0.4 (syst) ]×\times 107^{-7}, a value that is consistent with the standard model prediction

    Search for the Z boson decay to ττμμ\tau\tau\mu\mu in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe first search for the Z boson decay to ττμμ\tau\tau\mu\mu at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb1^{-1}. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the Z \to ττμμ\tau\tau\mu\mu to Z \to 4μ\mu branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two muons and two tau leptons, for the first time testing all such operators

    Search for soft unclustered energy patterns in proton-proton collisions at 13 TeV

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    International audienceThe first search for soft unclustered energy patterns (SUEPs) is performed using an integrated luminosity of 138 fb1^{-1} of proton-proton collision data at s\sqrt{s} = 13 TeV collected in 2016-2018 by the CMS detector at the LHC. Such SUEPs are predicted by Hidden Valley models with a new, confining force with a large 't Hooft coupling. In events with boosted topologies, selected by high-threshold hadronic triggers, the multiplicity and sphericity of clustered tracks are used to reject the background from standard model quantum chromodynamics. With no observed excess of events over the standard model expectation, limits are set on the cross section for production via gluon fusion of a scalar mediator with SUEP-like decays

    Search for long-lived heavy neutrinos in the decays of B mesons produced in proton-proton collisions at s= \sqrt{s} = 13 TeV

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    A search for long-lived heavy neutrinos (N) in the decays of B mesons produced in proton-proton collisions at s= \sqrt{s} = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb1 ^{-1} collected in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream that enhances the number of recorded events containing B mesons. The search probes heavy neutrinos with masses in the range 1 <mN< < m_\mathrm{N} < 3 GeV and decay lengths in the range 102^{-2} <cτN< < c\tau_{\mathrm{N}} < 104^{4} mm, where τN \tau_\mathrm{N} is the N proper mean lifetime. Signal events are defined by the signature B B\to \ell_{\mathrm{B}} NX; N ±π \to \ell^{\pm} \pi^{\mp} , where the leptons B \ell_{\mathrm{B}} and \ell can be either a muon or an electron, provided that at least one of them is a muon. The hadronic recoil system, X, is treated inclusively and is not reconstructed. No significant excess of events over the standard model background is observed in any of the ±π \ell^{\pm}\pi^{\mp} invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, VN2 |V_\mathrm{N}|^2 , and on cτN c\tau_{\mathrm{N}} are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit VN2< |V_\mathrm{N}|^2 < 2.0 ×\times 105^{-5} is obtained at mN= m_\mathrm{N}= 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on VN2 |V_\mathrm{N}|^2 for masses 1 <mN< < m_\mathrm{N} < 1.7 GeV are the most stringent from a collider experiment to date.A search for long-lived heavy neutrinos (N) in the decays of \PB mesons produced in proton-proton collisions at s\sqrt{s} = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb1^{-1} collected in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream that enhances the number of recorded events containing B mesons. The search probes heavy neutrinos with masses in the range 1 <\ltmNm_\mathrm{N}<\lt 3 GeV and decay lengths in the range 102^{-2}<\ltcτc\tau<\lt 104^{4} mm, where τN\tau_\mathrm{N} is the N proper mean lifetime. Signal events are defined by the signature B \toB\ell_\mathrm{B}NX; N \to±π\ell^{\pm} \pi^{\mp}, where the leptons B\ell_\mathrm{B} and \ell can be either a muon or an electron, provided that at least one of them is a muon. The hadronic recoil system, X, is treated inclusively and is not reconstructed. No significant excess of events over the standard model background is observed in any of the ±π\ell^{\pm}\pi^{\mp} invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, VN2\vert V_\mathrm{N}\vert^2, and on cτc\tau are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit VN2\vert V_\mathrm{N}\vert^2 <\lt 2.0×\times105^{-5} is obtained at mNm_\mathrm{N} = 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on VN2\vert V_\mathrm{N}\vert^2 for masses 1 <\lt mNm_\mathrm{N} <\lt 1.7 GeV are the most stringent from a collider experiment to date
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