195 research outputs found

    Modified Serum ALP Values and Timing of Apparition of Knee Epiphyseal Ossification Centers in Preterm Infants with Cholestasis and Risk of Concomitant Metabolic Bone Disease of Prematurity

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    The usefulness of serum alkaline phosphatase (ALP) and phosphorous in screening and monitoring of metabolic bone disease of prematurity (MBDP) still has some limitations, especially in preterm infants with concomitant conditions such as cholestasis. We aimed to assess a modification of serum ALP (M-ALP) as a biomarker for MBDP in preterm infants, and the use of ultrasound monitoring for the apparition of knee ossification centers as marker of bone mineralization. Biochemical and clinical registers were taken from 94 preterm newborns 1 was demonstrated to be more specific (87.5%) in the diagnosis of MBDP than the cut-off value of serum ALP > 500 IU/L (62.5%). ALP/M-ALP > 1 showed 100% sensitivity and specificity for the diagnosis of MBDP, and a good correlation with specific bone ALP (B-ALP). Patients with the knee nucleus by post-menstrual week 37 had lower B-ALP compared to patients with no nucleus, and no patients with MBDP presented the nucleus by the 40th week. In the absence of reliable specific B-ALP, reinterpreting serum ALP values by M-ALP plus monitoring of knee ossification centers contribute to better management of MBDP in preterm infants with cholestasis

    Firmware implementation of a displaced muon reconstruction algorithm for the Phase-2 Upgrade of the CMS muon system

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    Displaced muons serve as a crucial indicator of novel physics extending beyond the standard model. Several theoretical frameworks posit the existence of muons with extended lifetimes, which can materialize through collisions at the LHC. This study presents the firmware implementation of an algorithm to reconstruct displaced muons for the Overlap Muon Track Finder (OMTF) of the CMS Level-1 Trigger System (L1T) targeting the High Luminosity Large Hadron Collider (HL-LHC). The firmware response is evaluated at the simulation level, comparing the results with those of the emulator, and then the algorithm is implemented on an FPGA

    Search for CPCP violation in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} decays in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is reported for charge-parity D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S}CPCP violation in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} decays, using data collected in proton-proton collisions at s\sqrt{s} = 13 TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 fb1^{-1}, which consists of about 10 billion events containing a pair of ẖadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D+^{*+}\to D0π+^0\pi^+ and D^{*-}\to D0π^0\pi^-. The D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S}CPCP asymmetry in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} is measured to be ACPA_{CP}( KS0^0_\mathrm{S}KS0^0_\mathrm{S}) = (6.2 ±\pm 3.0 ±\pm 0.2 ±\pm 0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the D0^0 \to KS0^0_\mathrm{S}KS0^0_\mathrm{S} CPCP asymmetry in the D0^0 \to KS0π+π^0_\mathrm{S}\pi^+\pi^- decay. This is the first D0^0 \to KS0^0_\mathrm{S}KS0^0_\mathrm{S} CPCP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state

    Search for heavy neutral leptons in final states with electrons, muons, and hadronically decaying tau leptons in proton-proton collisions at s\sqrt{s} =13 TeV

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    International audienceA search for heavy neutral leptons (HNLs) of Majorana or Dirac type using proton-proton collision data at s\sqrt{s} =13 TeV is presented. The data were collected by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 138 fb1^{-1}. Events with three charged leptons (electrons, muons, and hadronically decaying tau leptons) are selected, corresponding to HNL production in association with a charged lepton and decay of the HNL to two charged leptons and a standard model (SM) neutrino. The search is performed for HNL masses between 10 GeV and 1.5 TeV. No evidence for an HNL signal is observed in data. Upper limits at 95% confidence level are found for the squared coupling strength of the HNL to SM neutrinos, considering exclusive coupling of the HNL to a single SM neutrino generation, for both Majorana and Dirac HNLs. The limits exceed previously achieved experimental constraints for a wide range of HNL masses, and the limits on tau neutrino coupling scenarios with HNL masses above the W boson mass are presented for the first time

    Search for nuclear modifications of B+^+ meson production in pPb collisions at sNN\sqrt{s_\mathrm{NN}} = 8.16 TeV

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    International audienceNuclear medium effects on B+^+ meson production are studied using the binary-collision scaled cross section ratio between events of different multiplicities from proton-lead collisions. Data, collected by the CMS experiment in 2016 at a nucleon-nucleon center-of-mass energy of sNN\sqrt{s_\mathrm{NN}} = 8.16 TeV, corresponding to an integrated luminosity of 175 nb1^{-1}, were used. The scaling factors in the ratio are determined using a novel approach based on the Z \toμ+μ\mu^+\mu^- cross sections measured in the same events. The scaled ratio for B+^+ is consistent with unity for all event multiplicities, putting stringent constraints on nuclear modification for heavy flavor

    Search for long-lived heavy neutral leptons in proton-proton collision events with a lepton-jet pair associated with a secondary vertex at s\sqrt{s} = 13 TeV

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    International audienceA search for long-lived heavy neutral leptons (HNLs) using proton-proton collision data corresponding to an integrated luminosity of 138 fb1^{-1} collected at s\sqrt{s} = 13 TeV with the CMS detector at the CERN LHC is presented. Events are selected with a charged lepton originating from the primary vertex associated with the proton-proton interaction, as well as a second charged lepton and a hadronic jet associated with a secondary vertex that corresponds to the semileptonic decay of a long-lived HNL. No excess of events above the standard model expectation is observed. Exclusion limits at 95% confidence level are evaluated for HNLs that mix with electron and/or muon neutrinos. Limits are presented in the mass range of 1-16.5 GeV, with excluded square mixing parameter values reaching as low as 2 ×\times 107^{-7}. For masses above 11 GeV, the presented limits exceed all previous results in the semileptonic decay channel, and for some of the considered scenarios are the strongest to date

    Search for CPCP violation in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} decays in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is reported for charge-parity D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S}CPCP violation in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} decays, using data collected in proton-proton collisions at s\sqrt{s} = 13 TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 fb1^{-1}, which consists of about 10 billion events containing a pair of ẖadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D+^{*+}\to D0π+^0\pi^+ and D^{*-}\to D0π^0\pi^-. The D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S}CPCP asymmetry in D0^0\to KS0^0_\mathrm{S}KS0^0_\mathrm{S} is measured to be ACPA_{CP}( KS0^0_\mathrm{S}KS0^0_\mathrm{S}) = (6.2 ±\pm 3.0 ±\pm 0.2 ±\pm 0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the D0^0 \to KS0^0_\mathrm{S}KS0^0_\mathrm{S} CPCP asymmetry in the D0^0 \to KS0π+π^0_\mathrm{S}\pi^+\pi^- decay. This is the first D0^0 \to KS0^0_\mathrm{S}KS0^0_\mathrm{S} CPCP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state

    Bottom quark energy loss and hadronization with B+^+ and Bs0^0_\mathrm{s} nuclear modification factors using pp and \PbPb collisions at sNN\sqrt{s_\mathrm{NN}} = 5.02 TeV

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    International audienceThe production cross sections of Bs0^0_\mathrm{s} and B+^+ mesons are reported in proton-proton (pp) collisions recorded by the CMS experiment at the CERN LHC with a center-of-mass energy of 5.02 TeV. The data sample corresponds to an integrated luminosity of 302 pb1^{-1}. The cross sections are based on measurements of the Bs0^0_\mathrm{s}\to J/ψ(μ+μ)ϕ\psi(\mu^+\mu^-)\phi(1020)(K+^+K^-) and B+^+\to J/ψ(μ+μ)\psi(\mu^+\mu^-)K+^+ decay channels. Results are presented in the transverse momentum (pTp_\mathrm{T}) range 7-50 GeV/cc and the rapidity interval y\lvert y \rvert<\lt 2.4 for the B mesons. The measured pTp_\mathrm{T}-differential cross sections of B+^+ and Bs0^0_\mathrm{s} in pp collisions are well described by fixed-order plus next-to-leading logarithm perturbative quantum chromodynamics calculations. Using previous PbPb collision measurements at the same nucleon-nucleon center-of-mass energy, the nuclear modification factors, RAAR_\mathrm{AA}, of the B mesons are determined. For pTp_\mathrm{T}<\lt 10 GeV/cc, both mesons are found to be suppressed in PbPb collisions (with RAAR_\mathrm{AA} values significantly below unity), with less suppression observed for the Bs0^0_\mathrm{s} mesons. In this pTp_\mathrm{T} range, the RAAR_\mathrm{AA} values for the B+^+ mesons are consistent with those for inclusive charged hadrons and D0^0 mesons. Below 10 GeV/cc, both B+^+ and Bs0^0_\mathrm{s}s are found to be less suppressed than either inclusive charged hadrons or D0^0 mesons, with the Bs0^0_\mathrm{s}RAAR_\mathrm{AA} value consistent with unity. The RAAR_\mathrm{AA} values found for the B+^+ and Bs0^0_\mathrm{s} are compared to theoretical calculations, providing constraints on the mechanism of bottom quark energy loss and hadronization in the quark-gluon plasma, the hot and dense matter created in ultrarelativistic heavy ion collisions

    Measurement of the ttˉ\mathrm{t\bar{t}}H and tH production rates in the H \tobbˉ\mathrm{b\bar{b}} decay channel using proton-proton collision data at s\sqrt{s} = 13 TeV

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    International audienceAn analysis of the production of a Higgs boson (H) in association with a top quark-antiquark pair (ttˉ\mathrm{t\bar{t}}H) or a single top quark (tH) is presented. The Higgs boson decay into a bottom quark-antiquark pair (H \tobbˉ\mathrm{b\bar{b}}) is targeted, and three different final states of the top quark decays are considered, defined by the number of leptons (electrons or muons) in the event. The analysis utilises proton-proton collision data collected at the CERN LHC with the CMS experiment at s\sqrt{s} = 13 TeV in 2016-2018, which correspond to an integrated luminosity of 138 fb1^{-1}. The observed ttˉ\mathrm{t\bar{t}}H production rate relative to the standard model expectation is 0.33 ±\pm 0.26 = 0.33 ±\pm 0.17 (stat) ±\pm 0.21 (syst). Additionally, the ttˉ\mathrm{t\bar{t}}H production rate is determined in intervals of Higgs boson transverse momentum. An upper limit at 95% confidence level is set on the tH production rate of 14.6 times the standard model prediction, with an expectation of 19.36.0+9.2^{+9.2}_{-6.0}. Finally, constraints are derived on the strength and structure of the coupling between the Higgs boson and the top quark from simultaneous extraction of the ttˉ\mathrm{t\bar{t}}H and tH production rates, and the results are combined with those obtained in other Higgs boson decay channels

    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
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