Showing papers by "Pablo Garcia-Abia published in 2018"
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TL;DR: In this article, a measurement of the H→ττ signal strength is performed using events recorded in proton-proton collisions by the CMS experiment at the LHC in 2016 at a center-of-mass energy of 13TeV.
250 citations
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TL;DR: In this paper, a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more hadronically decaying tau-leptons.
Abstract: Results are presented from a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more leptons, which can include up to two hadronically decaying tau leptons. The results are based on a sample of proton-proton collision data collected at $ \sqrt{s}=13 $ TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. The observed event yields are consistent with the expectations based on the standard model. The results are interpreted in simplified models of supersymmetry describing various scenarios for the production and decay of charginos and neutralinos. Depending on the model parameters chosen, mass values between 180 GeV and 1150 GeV are excluded at 95% CL. These results significantly extend the parameter space probed for these particles in searches at the LHC. In addition, results are presented in a form suitable for alternative theoretical interpretations.
158 citations
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TL;DR: In this paper, a search for the production of Higgs boson pairs in proton-proton collisions at a centre-of-mass energy of 13 TeV is presented, using a data sample corresponding to an integrated luminosity of 35.9fb^(−1) collected with the CMS detector at the LHC.
123 citations
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TL;DR: In this article, the authors performed searches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into l nu l nu, through either W or Z bosons, and b (b) over bar.
Abstract: Searches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into l nu l nu, through either W or Z bosons, and b (b) over bar are presented The analyses are based on a sample of proton-proton collisions at root s = 13 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 359 fb(-1) Data and predictions from the standard model are in agreement within uncertainties For the standard model HH hypothesis, the data exclude at 95% confidence level a product of the production cross section and branching fraction larger than 72 fb, corresponding to 79 times the standard model prediction Constraints are placed on different scenarios considering anomalous couplings, which could affect the rate and kinematics of HH production Upper limits at 95% confidence level are set on the production cross section of narrow-width spin-0 and spin-2 particles decaying to Higgs boson pairs, the latter produced with minimal gravity-like coupling
121 citations
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TL;DR: In this paper, the transverse momentum (p_T) spectrum of prompt D0 mesons and their antiparticles has been measured via the hadronic decay channels D^0 → K^−π+ and D^‾0 → k^+π^− in pp and PbPb collisions at a centre-of-mass energy of 5.02
113 citations
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TL;DR: An inclusive search for the standard model Higgs boson produced with large transverse momentum (p_{T}) and decaying to a bottom quark-antiquark pair (bb[over ¯]) is performed using a data set of pp collisions collected with the CMS experiment at the LHC.
Abstract: An inclusive search for the standard model Higgs boson (H) produced with large transverse momentum (p_T) and decaying to a bottom quark-antiquark pair (bb) is performed using a data set of pp collisions at √s = 13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of
35.9 fb^(−1). A highly Lorentz-boosted Higgs boson decaying to bb is reconstructed as a single, large radius jet, and it is identified using jet substructure and dedicated b tagging techniques. The method is validated with Z → bb decays. The Z → bb process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of H → bb with reconstructed p_T > 450 GeV and in the pseudorapidity range −2.5 < η < 2.5 is 74 ± 48 (stat)^(+17)_(−10)(syst) fb, which is consistent within uncertainties with the standard model prediction.
106 citations
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TL;DR: In this article, a single production of a vector-like quark (T) decaying to a Z boson and a top quark was studied, with T → tZ decaying leptonically and tZ → tT decaying hadronically.
81 citations
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TL;DR: In this article, the prompt D0 meson azimuthal anisotropy coefficients, v2 and v3, are measured at midrapidity (|y| < 1.0) in Pb-Pb collisions at a center-of-mass energy sNN=5.02
Abstract: The prompt D0 meson azimuthal anisotropy coefficients, v2 and v3, are measured at midrapidity (|y|<1.0) in Pb-Pb collisions at a center-of-mass energy sNN=5.02 TeV per nucleon pair with data collected by the CMS experiment. The measurement is performed in the transverse momentum (pT) range of 1 to 40 GeV/c, for central and midcentral collisions. The v2 coefficient is found to be positive throughout the pT range studied. The first measurement of the prompt D0 meson v3 coefficient is performed, and values up to 0.07 are observed for pT around 4 GeV/c. Compared to measurements of charged particles, a similar pT dependence, but smaller magnitude for pT<6 GeV/c, is found for prompt D0 meson v2 and v3 coefficients. The results are consistent with the presence of collective motion of charm quarks at low pT and a path length dependence of charm quark energy loss at high pT, thereby providing new constraints on the theoretical description of the interactions between charm quarks and the quark-gluon plasma.
67 citations
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TL;DR: In this paper, a search in the dijet final state for new massive narrow resonances decaying to pairs of W and Z bosons or to a W/Z boson and a quark is presented.
Abstract: Results are presented from a search in the dijet final state for new massive narrow resonances decaying to pairs of W and Z bosons or to a W/Z boson and a quark. Results are based on data recorded in proton-proton collisions at √s = 13 TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 35.9 fb^(−1). The mass range investigated extends upwards from 1.2 TeV. No excess is observed above the estimated standard model background and limits are set at 95% confidence level on cross sections, which are interpreted in terms of various models that predict gravitons, heavy spin-1 bosons, and excited quarks. In a heavy vector triplet model, W′ and Z′ resonances, with masses below 3.2 and 2.7 TeV, respectively, and spin-1 resonances with degenerate masses below 3.8 TeV are excluded at 95% confidence level. In the case of a singlet W′resonance masses between 3.3 and 3.6 TeV can be excluded additionally. Similarly, excited quark resonances, q∗, decaying to qW and qZ with masses less than 5.0 and 4.7 TeV, respectively, are excluded. In a narrow-width bulk graviton model, upper limits are set on cross sections ranging from 0.6 fb for high resonance masses above 3.6 TeV, to 36.0 fb for low resonance masses of 1.3 TeV.
66 citations
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TL;DR: In this paper, the Fourier coefficients v[2] and v[3] characterizing the anisotropy of the azimuthal distribution of charged particles produced in PbPb collisions at sqrt(s[NN]) = 5.02 TeV are measured with data collected by the CMS experiment.
65 citations
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TL;DR: Differential production cross sections of prompt J/ψ and ψ(2S) charmonium and ϒ(nS) (n=1,2,3) bottomonium states are measured in proton-proton collisions at √s = 13 TeV, with data collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb^(−1) for the J/ ψ and 2.7 fb+1 for the other mesons as mentioned in this paper.
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TL;DR: In this paper, a search for the production of vector-like quark pairs, TT or YY, with electric charge of 2/3 (T) or −4/3(Y), in proton-proton collisions at √s = 13 TeV was presented.
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TL;DR: The azimuthal anisotropy Fourier coefficients (v_{n}) in 8.16 TeV p+Pb data are extracted via long-range two-particle correlations as a function of the event multiplicity and compared to corresponding results in pp and PbPb collisions, finding the v_{2} and v_{4} coefficients to be positively correlated in all collision systems.
Abstract: The azimuthal anisotropy Fourier coefficients (v_n) in 8.16 TeV p+Pb data are extracted via long-range two-particle correlations as a function of the event multiplicity and compared to corresponding results in
pp and PbPb collisions. Using a four-particle cumulant technique, v_n correlations are measured for the first time in pp and p+Pb collisions. The v_2 and v_4 coefficients are found to be positively correlated in all collision systems. For high-multiplicity p+Pb collisions, an anticorrelation of v_2 and v_3 is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in
p+Pb and PbPb collisions in the measured multiplicity range.
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TL;DR: In this paper, a search for the pair production of third-generation squarks in proton-proton collision events with two-body decays to bottom or charm quarks and a neutralino, which produces a significant imbalance in the transverse momentum.
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TL;DR: The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ γ couplings at 95% confidence level and the results agree with standard model predictions.
Abstract: Four-lepton production in proton-proton collisions, $\mathrm {p}\mathrm {p}\rightarrow (\mathrm{Z}/ \gamma ^*)(\mathrm{Z}/\gamma ^*) \rightarrow 4\ell $ , where $\ell = \mathrm {e}$ or $\mu $ , is studied at a center-of-mass energy of 13 $\,\text {TeV}$ with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 35.9 $\,\text {fb}^{-1}$ . The ZZ production cross section, $\sigma (\mathrm {p}\mathrm {p}\rightarrow \mathrm{Z}\mathrm{Z}) = 17.2 \pm 0.5\,\text {(stat)} \pm 0.7\,\text {(syst)} \pm 0.4\,\text {(theo)} \pm 0.4\,\text {(lumi)} \text { pb} $ , measured using events with two opposite-sign, same-flavor lepton pairs produced in the mass region $60 4\,\text {GeV} $ for all opposite-sign, same-flavor lepton pairs. The results agree with standard model predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ $\gamma $ couplings at 95% confidence level: $-0.0012
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TL;DR: In this paper, the PTOLEMY project has been used to directly detect the Cosmic Neutrino Background (CNB) using low background environment provided by the LNGS underground site.
Abstract: We propose to achieve the proof-of-principle of the PTOLEMY project to directly detect the Cosmic Neutrino Background (CNB). Each of the technological challenges described in [1,2] will be targeted and hopefully solved by the use of the latest experimental developments and profiting from the low background environment provided by the LNGS underground site. The first phase will focus on the graphene technology for a tritium target and the demonstration of TES microcalorimetry with an energy resolution of better than 0.05 eV for low energy electrons. These technologies will be evaluated using the PTOLEMY prototype, proposed for underground installation, using precision HV controls to step down the kinematic energy of endpoint electrons to match the calorimeter dynamic range and rate capabilities. The second phase will produce a novel implementation of the EM filter that is scalable to the full target size and which demonstrates intrinsic triggering capability for selecting endpoint electrons. Concurrent with the CNB program, we plan to exploit and develop the unique properties of graphene to implement an intermediate program for direct directional detection of MeV dark matter [3,4]. This program will evaluate the radio-purity and scalability of the graphene fabrication process with the goal of using recently identified ultra-high radio-purity CO2 sources. The direct detection of the CNB is a snapshot of early universe dynamics recorded by the thermal relic neutrino yield taken at a time that predates the epochs of Big Bang Nucleosynthesis, the Cosmic Microwave Background and the recession of galaxies (Hubble Expansion). Big Bang neutrinos are believed to have a central role in the evolution of the Universe and a direct measurement with PTOLEMY will unequivocally establish the extent to which these predictions match present-day neutrino densities.
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TL;DR: In this article, a search for long-lived particles was performed with data corresponding to an integrated luminosity of 2.6 fb−1 collected at a center-of-mass energy of 13 TeV by the CMS experiment in 2015.
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TL;DR: In this article, the yields of mesons produced in pp and Pb-Pb collisions at sNN=5.02 ǫTeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment.
Abstract: The relative yields of ϒ mesons produced in pp and Pb-Pb collisions at sNN=5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, ϒ(2S) and ϒ(3S), to the ground state, ϒ(1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [ϒ(nS)/ϒ(1S)]Pb-Pb/[ϒ(nS)/ϒ(1S)]pp, are measured to be 0.308±0.055(stat)±0.019(syst) for the ϒ(2S) and less than 0.26 at 95% confidence level for the ϒ(3S). No significant ϒ(3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as ϒ transverse momentum and rapidity. No significant dependencies are observed.
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TL;DR: In this paper, the cross sections for the production of tt-bar bb-bar and ttbar jj events and their ratio sigma[tt-bar bar]/sigma[t-Bar jj] were measured using data corresponding to an integrated luminosity of 2.3 inverse femtobarns collected in pp collisions at the LHC.
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TL;DR: In this paper, Bose-Einstein correlations are measured in pPb and peripheral PbPb collisions at nucleon-nucleon center-of-mass energies of 5.02 and 2.76 TeV, respectively, using the CMS detector at the Large Hadron Collider.
Abstract: Quantum-statistical (Bose-Einstein) two-particle correlations are measured in pp collisions at root s = 0.9, 2.76, and 7 TeV, as well as in pPb and peripheral PbPb collisions at nucleon-nucleon center-of-mass energies of 5.02 and 2.76 TeV, respectively, using the CMS detector at the Large Hadron Collider. Separate analyses are performed for same-sign unidentified charged particles as well as for same-sign pions and kaons identified via their energy loss in the silicon tracker. The characteristics of the one-, two-, and three-dimensional correlation functions are studied as functions of the pair average transverse momentum (k(T)) and the charged-particle multiplicity in the event. For all systems, the extracted correlation radii steadily increase with the event multiplicity, and decrease with increasing k(T). The radii are in the range 1-5 fm, the largest values corresponding to very high multiplicity pPb interactions and to peripheral PbPb collisions with multiplicities similar to those seen in pPb data. It is also observed that the dependencies of the radii on multiplicity and k(T) largely factorize. At the same multiplicity, the radii are relatively independent of the colliding system and center-of-mass energy.
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TL;DR: The top quark pair production cross section was measured for the first time in pp collisions at a center-of-mass energy of 5.02 TeV in this paper, which correspond to an integrated luminosity of 27.4 pb$−1.
Abstract: The top quark pair production cross section $ \left({\sigma}_{\mathrm{t}\overline{\mathrm{t}}}\right) $ is measured for the first time in pp collisions at a center-of-mass energy of 5.02 TeV. The data were collected by the CMS experiment at the LHC and correspond to an integrated luminosity of 27.4 pb$^{−1}$. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is $ {\sigma}_{\mathrm{t}\overline{\mathrm{t}}} $ = 69.5 ± 6.1 (stat) ± 5.6 (syst) ± 1.6 (lumi) pb, with a total relative uncertainty of 12%. The result is in agreement with the expectation from the standard model. The impact of the presented measurement on the determination of the gluon distribution function is investigated.
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TL;DR: In this paper, a search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states.
Abstract: A first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb−1. No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions.
01 Jan 2018
TL;DR: Doser et al. as mentioned in this paper presented a survey of the state of the art in the field of cyber-physical cyber-warrior networks and proposed a method to improve it.
Abstract: Article history: Received 10 July 2017 Received in revised form 28 December 2017 Accepted 1 January 2018 Available online 9 January 2018 Editor: M. Doser
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TL;DR: In this article, a search for new physics is carried out in events with at least three electrons or muons in any combination, jets, and missing transverse momentum, and the invariant mass of same-flavor dilepton pairs with opposite charge.
Abstract: A search for new physics is carried out in events with at least three electrons or muons in any combination, jets, and missing transverse momentum. Results are based on the sample of proton-proton collision data produced by the LHC at a center-of-mass energy of 13 TeV and collected by the CMS experiment in 2016. The data sample analyzed corresponds to an integrated luminosity of 35.9 fb^(−1). Events are classified according to the number of b jets, missing transverse momentum, hadronic transverse momentum, and the invariant mass of same-flavor dilepton pairs with opposite charge. No significant excess above the expected standard model background is observed. Exclusion limits at 95% confidence level are computed for four different supersymmetric simplified models with pair production of gluinos or third-generation squarks. In the model with gluino pair production, with subsequent decays into a top quark-antiquark pair and a neutralino, gluinos with masses smaller than 1610 GeV are excluded for a massless lightest supersymmetric particle. In the case of bottom squark pair production, the bottom squark masses are excluded up to 840 GeV for charginos lighter than 200 GeV. For a simplified model of heavy top squark pair production, the t_2 mass is excluded up to 720, 780, or 710 GeV for models with an exclusive t_2 → t_1 H decay, an exclusive t_2 → t_1 Z decay, or an equally probable mix of those two decays. In order to provide a simplified version of the analysis for easier interpretation, a small set of aggregate signal regions also has been defined, providing a compromise between simplicity and analysis sensitivity.
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TL;DR: In this paper, a search for narrow heavy resonances decaying to a top quark and a bottom quark using data collected by the CMS experiment at √s = 13 TeV in 2016 is presented.
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TL;DR: In this paper, a measurement of the underlying event activity in proton-proton collisions at a center-of-mass energy of 13 TeV was performed using Z boson production events collected with the CMS experiment at the LHC.
Abstract: This paper presents a measurement of the underlying event activity in proton-proton collisions at a center-of-mass energy of 13 TeV, performed using inclusive Z boson production events collected with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 2.1 fb−1. The underlying event activity is quantified in terms of the charged particle multiplicity, as well as of the scalar sum of the charged particles’ transverse momenta in different topological regions defined with respect to the Z boson direction. The distributions are unfolded to the stable particle level and compared with predictions from various Monte Carlo event generators, as well as with similar CDF and CMS measurements at center-of-mass energies of 1.96 and 7 TeV respectively.
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TL;DR: In this article, an inclusive search for anomalous Higgs boson production in the diphoton decay channel and in association with at least one jet is presented, using LHC proton-proton collision data collected by the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 35.9fb^(−1).
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TL;DR: In this paper, a search for new physics in 13TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H→bb¯ was conducted.
Abstract: Results are reported from a search for new physics in 13 TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H→bb¯ The search uses a data sample accumulated by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 359 fb-1 The search is motivated by models based on gauge-mediated supersymmetry breaking, which predict the electroweak production of a pair of Higgsinos, each of which can decay via a cascade process to a Higgs boson and an undetected lightest supersymmetric particle The observed event yields in the signal regions are consistent with the standard model background expectation obtained from control regions in data Higgsinos in the mass range 230–770 GeV are excluded at 95% confidence level in the context of a simplified model for the production and decay of approximately degenerate Higgsinos
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TL;DR: In this article, a search for supersymmetry in events with a single electron or muon and hadronic jets is presented, and the results are used to set lower limits on supersymmetric particle masses in the context of two simplified models of gluino pair production.