725 research outputs found

    Production of gamma rays and neutrinos in the dark jets of the microquasar SS433

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    We study the spectral energy distribution of gamma rays and neutrinos in the precessing microquasar SS433 as a result of pp interactions within its dark jets. Gamma-ray absorption due to interactions with matter of the extended disk and of the star is found to be important, as well as absorption caused by the UV and mid-IR radiation from the equatorial envelopment. We analyze the range of precessional phases for which this attenuation is at a minimum and the chances for detection of a gamma-ray signal are enhanced. The power of relativistic protons in the jets, a free parameter of the model, is constrained by HEGRA data. This imposes limits on the gamma-ray fluxes to be detected with instruments such as GLAST, VERITAS and MAGIC II. A future detection of high energy neutrinos with cubic kilometer telescopes such as IceCube would also yield important information about acceleration mechanisms that may take place in the dark jets. Overall, the determination of the ratio of gamma-ray to neutrino flux will result in a key observational tool to clarify the physics of heavy jets.Comment: 10 pages, 13 figures. Accepted for publication in MNRA

    Detection of recurrent copy number alterations in the genome: taking among-subject heterogeneity seriously

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    Se adjunta un fichero pdf con los datos de investigación titulado "Supplementary Material for \Detection of Recurrent Copy Number Alterations in the Genome: taking among-subject heterogeneity seriously"Background: Alterations in the number of copies of genomic DNA that are common or recurrent among diseased individuals are likely to contain disease-critical genes. Unfortunately, defining common or recurrent copy number alteration (CNA) regions remains a challenge. Moreover, the heterogeneous nature of many diseases requires that we search for common or recurrent CNA regions that affect only some subsets of the samples (without knowledge of the regions and subsets affected), but this is neglected by most methods. Results: We have developed two methods to define recurrent CNA regions from aCGH data. Our methods are unique and qualitatively different from existing approaches: they detect regions over both the complete set of arrays and alterations that are common only to some subsets of the samples (i.e., alterations that might characterize previously unknown groups); they use probabilities of alteration as input and return probabilities of being a common region, thus allowing researchers to modify thresholds as needed; the two parameters of the methods have an immediate, straightforward, biological interpretation. Using data from previous studies, we show that we can detect patterns that other methods miss and that researchers can modify, as needed, thresholds of immediate interpretability and develop custom statistics to answer specific research questions. Conclusion: These methods represent a qualitative advance in the location of recurrent CNA regions, highlight the relevance of population heterogeneity for definitions of recurrence, and can facilitate the clustering of samples with respect to patterns of CNA. Ultimately, the methods developed can become important tools in the search for genomic regions harboring disease-critical genesFunding provided by Fundación de Investigación Médica Mutua Madrileña. Publication charges covered by projects CONSOLIDER: CSD2007-00050 of the Spanish Ministry of Science and Innovation and by RTIC COMBIOMED RD07/0067/0014 of the Spanish Health Ministr

    Measurements of production cross sections of WZ and same-sign WWboson pairs in association with two jets in proton-proton collisions at √s=13 TeV

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    Measurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at s=13TeV at the LHC are reported. The data sample corresponds to an integrated luminosity of 137fb−1, collected with the CMS detector during 2016–2018. The measurements are performed in the leptonic decay modes [Formula presented] and [Formula presented], where ℓ,ℓâ€Č=e, [Formula presented]. Differential fiducial cross sections as functions of the invariant masses of the jet and charged lepton pairs, as well as of the leading-lepton transverse momentum, are measured for W±W± production and are consistent with the standard model predictions. The dependence of differential cross sections on the invariant mass of the jet pair is also measured for WZ production. An observation of electroweak production of WZ boson pairs is reported with an observed (expected) significance of 6.8 (5.3) standard deviations. Constraints are obtained on the structure of quartic vector boson interactions in the framework of effective field theory

    Measurement of double-parton scattering in inclusive production of four jets with low transverse momentum in proton-proton collisions at root s=13 TeV

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    A measurement of inclusive four-jet production in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The transverse momenta of jets within vertical bar eta vertical bar 4.7 are required to exceed 35, 30, 25, and 20 GeV for the first-, second-, third-, and fourth-leading jet, respectively. Differential cross sections are measured as functions of the jet transverse momentum, jet pseudorapidity, and several other observables that describe the angular correlations between the jets. The measured distributions show sensitivity to different aspects of the underlying event, parton shower modeling, and matrix element calculations. In particular, the interplay between angular correlations caused by parton shower and double-parton scattering contributions is shown to be important. The double-parton scattering contribution is extracted by means of a template fit to the data, using distributions for single-parton scattering obtained from Monte Carlo event generators and a double-parton scattering distribution constructed from inclusive single-jet events in data. The effective double-parton scattering cross section is calculated and discussed in view of previous measurements and of its dependence on the models used to describe the single-parton scattering background

    Measurement of the inclusive and differential t(t)over-bar gamma cross sections in the single-lepton channel and EFT interpretation at root s=13 TeV

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    Peer reviewe

    Nuclear modification of Y states in pPb collisions at √SNN_{NN} = 5.02 TeV

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    Production cross sections of ΄(1S), ΄(2S), and ΄(3S) states decaying into ÎŒ+Ό− in proton-lead (pPb) collisions are reported using data collected by the CMS experiment at √sNN = 5.02 TeV. A comparison is made with corresponding cross sections obtained with pp data measured at the same collision energy and scaled by the Pb nucleus mass number. The nuclear modification factor for ΄(1S) is found to be RpPb(΄(1S)) = 0.806±0.024 (stat)±0.059 (syst). Similar results for the excited states indicate a sequential suppression pattern, such that RpPb(΄(1S)) > RpPb(΄(2S)) > RpPb(΄(3S)). The suppression of all states is much less pronounced in pPb than in PbPb collisions, and independent of transverse momentum p΄T and center-of-mass rapidity y΄CM of the individual ΄ state in the studied range p ΄T < 30 GeV/c and |y΄CM| <1.93. Models that incorporate final-state effects of bottomonia in pPb collisions are in better agreement with the data than those which only assume initial-state modifications

    Measurements of (tt)over-barH Production and the CP Structure of the Yukawa Interaction between the Higgs Boson and Top Quark in the Diphoton Decay Channel

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    The first observation of the (tt) over barH process in a single Higgs boson decay channel with the full reconstruction of the final state (H -> gamma gamma) is presented, with a significance of 6.6 standard deviations (sigma). The CP structure of Higgs boson couplings to fermions is measured, resulting in an exclusion of the pure CP-odd structure of the top Yukawa coupling at 3.2 sigma. The measurements are based on a sample of protonproton collisions at a center-of-mass energy root s = 13 TeV collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb(-1). The cross section times branching fraction of the (tt) over barH process is measured to be sigma B-(tt) over barH(gamma gamma) = 1.56(-0.32)(+0.34) th, which is compatible with the standard model prediction of 1.13(-0.11)(+0.08) fb. The fractional contribution of the CP-odd component is measured to be f(CP)(Hu) = 0.00 +/- 0.33.Peer reviewe

    Constraints on the Initial State of Pb-Pb Collisions via Measurements of Z-Boson Yields and Azimuthal Anisotropy at root s(NN)=5.02 TeV

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    The CMS experiment at the LHC has measured the differential cross sections of Z bosons decaying to pairs of leptons, as functions of transverse momentum and rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is compatible with zero, showing that Z bosons do not experience significant final-state interactions in the medium produced in the collision. Yields of Z bosons are compared to Glauber model predictions and are found to deviate from these expectations in peripheral collisions, indicating the presence of initial collision geometry and centrality selection effects. The precision of the measurement allows, for the first time, for a data-driven determination of the nucleon-nucleon integrated luminosity as a function of lead-lead centrality, thereby eliminating the need for its estimation based on a Glauber model.Peer reviewe

    Measurement of the Higgs boson width and evidence of its off-shell contributions to ZZ production

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    Since the discovery of the Higgs boson in 2012, detailed studies of its properties have been ongoing. Besides its mass, its width—related to its lifetime—is an important parameter. One way to determine this quantity is to measure its off-shell production, where the Higgs boson mass is far away from its nominal value, and relating it to its on-shell production, where the mass is close to the nominal value. Here we report evidence for such off-shell contributions to the production cross-section of two Z bosons with data from the CMS experiment at the CERN Large Hadron Collider. We constrain the total rate of the off-shell Higgs boson contribution beyond the Z boson pair production threshold, relative to its standard model expectation, to the interval [0.0061, 2.0] at the 95% confidence level. The scenario with no off-shell contribution is excluded at a p-value of 0.0003 (3.6 standard deviations). We measure the width of the Higgs boson as Γ\GammaH_H=3.2−1.7+2.4^{+2.4}_{−1.7}MeV, in agreement with the standard model expectation of 4.1 MeV. In addition, we set constraints on anomalous Higgs boson couplings to W and Z boson pairs

    Using Z boson events to study parton-medium interactions in Pb-Pb collisions

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    The spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson are reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7  nb^{-1} and 320  pb^{-1}, respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum p_{T}>30  GeV/c are analyzed. The Z boson constrains the initial energy and direction of the associated parton. In heavy ion events, azimuthal angular distributions of charged hadrons with respect to the direction of a Z boson are sensitive to modifications of the in-medium parton shower and medium response. compared to reference data from pp interactions, the results for central Pb-Pb collisions indicate a modification of the angular correlations. The measurements of the fragmentation functions and p_{T} spectra of charged particles in Z boson events, which are sensitive to medium modifications of the parton shower longitudinal structure, are also reported. Significant modifications in central Pb-Pb events compared to the pp reference data are also found for these observables
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