1,668 research outputs found
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
Study of charm hadronization with prompt Λ c + baryons in proton-proton and lead-lead collisions at s NN = 5.02 TeV
No full textAbstract The production of prompt Λ c + baryons is measured via the exclusive decay channel Λ c + → p K − π + at a center-of-mass energy per nucleon pair of 5.02 TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb −1, respectively. The measurements are performed within the Λ c + rapidity interval |y| 10 GeV/c are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The Λ c + /D0 production ratio is similar in PbPb and pp collisions at p T > 10 GeV/c, suggesting that the coalescence process does not play a dominant role in prompt Λ c + baryon production at higher p T
Irradiation aging of the CMS Drift Tube muon detector
No full textFerrero, D.D.R., Abbiendi, G., Maestre, J.A., Fernández, A.Á., González, B.Á., Amapane, N., Bachiller, I., Barcala, J.M., Barcellan, L., Battilana, C., Bellato, M., Bencze, G., Benettoni, M., Beni, N., Benvenuti, A., Ramos, L.C.B., Boletti, A., Bragagnolo, A., Cifuentes, J.A.B., Cafaro, V., Calderon, A., Calvo, E., Cappati, A., Carlin, R., Montoya, C.A.C., Caturan, S., Cavallo, F.R., Ruiz, J.M.C., Cepeda, M., Cerrada, M., Quero, B.C., Checchia, P., Ciano, L., Colino, N., Corti, D., Cotto, G., Cuevas, J., Cuffiani, M., Dallavalle, G.M., Dattola, D., De La Cruz, B., De Remigis, P., de Trocóniz, J.F., Cid, C.E., Bedoya, C.F., Fabbri, F., Fanfani, A., Fasanella, D., Manteca, P.F., Menéndez, J.F., Ramos, J.P.F., Folgueras, S., Fouz, M.C., Ferrero, D.F., Romero, J.G., Gasparini, F., Gasparini, U., Giordano, V., Casademunt, F.G., Gonella, F., Caballero, I.G., Fernández, J.R.G., López, O.G., Gosh, S., López, S.G., Gozzelino, A., Griggio, A., Grosso, G., Guandalini, C., Guiducci, L., Gulmini, M., Hebbeker, T., Heidemann, C., Hernández, J.M., Hoepfner, K., Iemmi, F., Isocrate, R., Josa, M.I., Kiani, B., Lacaprara, S., Lo Meo, S., Marcellini, S., Margoni, M., Marín, J., Mariotti, C., Martín, I.M., Morales, J.J.M., Rivero, C.M., Maselli, S., Masetti, G., Meneguzzo, A.T., Merschmeyer, M., Mocellin, G., Modenese, L., Molinero, A., Molnar, J., Montecassiano, F., Moran, D., Navarrete, J.J., Navarria, F., Tobar, Á.N., Oller, J.C., Passaseo, M., Pazzini, J., Pegoraro, M., Pelayo, J.P., Pelliccioni, M., Philipps, B., Gomez, J.P., Angioni, G.L.P., Pozzobon, N., Presilla, M., Prieels, C., Primavera, F., Sánchez, J.C.P., Redondo, I., Reithler, H., Rodrigo, T., Bouza, V.R., Roemer, J., Ronchese, P., Rossin, R., Rotondo, F., Rovelli, T., Cruz, S.S., Navas, S.S., Sastre, J., Scodellaro, L., Simonetto, F., Soares, M.S., Staiano, A., Szillasi, Z., Teyssier, D.F., Toniolo, N., Torassa, E., Trocino, D., Ujvari, B., Ventura, S., Cortabitarte, R.V., Garcia, J.V., Zanetti, M., Zantis, F.P., Zilizi, G., Zotto, P
Interobserver agreement rate of the spontaneous breathing trial
No full textConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Purpose: During the mechanical ventilation weaning process, the spontaneous breathing trial (SBT) is the confirmatory test of patients' capability to breathe unassisted. However, the SBT interobserver agreement rate (its reliability) is unknown, and our objective was to evaluate it. Materials and Methods: This is a prospective, multicentric and observational study. Patients were included when the SBT criteria were fulfilled. Two physicians and 2 respiratory therapists (RTs) rated each SBT. The SBT interobserver agreement was measured using kappa statistic and also the percentage of agreement with its 95% credible interval (CrI) calculated by a Bayesian inference. Results: Ninety-three distinct physicians and 91 distinct RTs rated 130 SBTs. The kappa coefficient was 0.46 for physicians and 0.57 for RT, indicating a moderate interobserver agreement rate. The percentage of agreement was 87.7% between physicians (95% CrI, 81.0%-92.3%) and 86.2% between RT (95% CrI, 79.2%-91.1%). The physicians' and RT' percentage of agreement were not statistically different (P = .71). Conclusions: The SBT interobserver agreement rate is only moderate for physicians and RT. The percentage of agreement between 2 different SBT observers is 79.2% to 92.3%. Therefore, a relevant percentage of patients will have different extubation decisions depending on the SBT observer. (c) 2013 Elsevier Inc. All rights reserved.2816268Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Measurement of the production cross section for a W boson in association with a charm quark in proton–proton collisions at √s=13TeV
No full textThe strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton–proton collisions at a center-of-mass energy of 13 TeV . The analysis uses a data sample corresponding to a total integrated luminosity of 138 fb-1 collected with the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm jets are tagged using the presence of a muon or a secondary vertex inside the jet. The W + c production cross section and the cross section ratio Rc±=σ(W++c¯)/σ(W-+c) are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in Rc±=0.950±0.005(stat)±0.010(syst) . The measurements are compared with theoretical predictions up to next-to-next-to-leading order in perturbative quantum chromodynamics
Measurement of the production cross section for a W boson in association with a charm quark in proton-proton collisions at √s=13 TeV
No full textThe strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton–proton collisions at a center-of-mass energy of 13 TeV . The analysis uses a data sample corresponding to a total integrated luminosity of 138 fb-1 collected with the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm jets are tagged using the presence of a muon or a secondary vertex inside the jet. The W + c production cross section and the cross section ratio Rc±=σ(W++c ̄)/σ(W-+c) are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in Rc±=0.950±0.005(stat)±0.010(syst) . The measurements are compared with theoretical predictions up to next-to-next-to-leading order in perturbative quantum chromodynamics
LEMMA approach for the production of low-emittance muon beams
No full textThis work introduces an experimental test of the new proposal for a low–emittance muon accelerator (LEMMA). A low–emittance muon beam is obtained from the e+e− → μ+μ− annihilation process at the threshold energy of 45 GeV eliminating the need for a dedicated muon cooling system. A series of two testbeam campaigns were carried out at CERN to validate this concept. The experimental setup is presented together with first preliminary results from the obtained data
Two-particle azimuthal correlations in γp interactions using pPb collisions at √s_NN=8.16 TeV
No full textThe first measurements of the Fourier coefficients (V-n Delta) of the azimuthal distributions of charged hadrons emitted from photon-proton (gamma p) interactions are presented. The data are extracted from 68.8nb(-1) of ultra-peripheral proton-lead (pPb) collisions at root s(NN)= 8.16 TeV using the CMS detector. The high energy lead ions produce a flux of photons that can interact with the oncoming proton. This gamma p system provides a set of unique initial conditions with multiplicity lower than in photon-lead collisions but comparable to recent electron-positron and electron-proton data. The V-n Delta coefficients are presented in ranges of event multiplicity and transverse momentum (p(T)) and are compared to corresponding hadronic minimum bias pPb results. For a given multiplicity range, the mean p(T) of charged particles is smaller in gamma p than in pPb collisions. For both the gamma p and pPb samples, V-1 Delta is negative, V-2 Delta is positive, and V-3 Delta consistent with 0. For each multiplicity and p(T) range, V-2 Delta is larger for gamma p events. The gamma p data are consistent with model predictions that have no collective effects. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3)
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
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