11 research outputs found

    Search for a very light NMSSM Higgs boson produced in decays of the 125 GeV scalar boson and decaying into tau leptons in pp collisions at root 8=TeV

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    Measurement of neutral strange particle production in the underlying event in proton-proton collisions at √s = 7 TeV

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    Measurements are presented of the production of primary K0 S and Λ particles in proton-proton collisions at √s = 7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar trans- verse momentum sum of K0 S and Λ particles measured at pseudorapidities |η| < 2 rise with increasing charged-particle jet pT in the range 1–10 GeV/c and saturate in the re- gion 10–50 GeV/c. The rise and saturation of the strange particle yields and transverse momentum sums in the underlying event are similar to those observed for inclusive charged particles, which confirms the impact-parameter picture of multiple parton interactions. The results are compared to recent tunes of the PYTHIA Monte Carlo event generator. The PYTHIA simulations underestimate the data by 15–30% for K0 S mesons and by about 50% for Λ baryons, a deficit similar to that observed for the in- clusive strange particle production in non-single-diffractive proton-proton collisions. The constant strange- to charged-particle activity ratios with respect to the leading jet pT and the similar trends for mesons and baryons indicate that the multiparton- interaction dynamics is decoupled from parton hadronization, which occurs at a later stage

    Search for new physics in events with a leptonically decaying Z boson and a large transverse momentum imbalance in proton-proton collisions at root s=13 TeV

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    A search for new physics in events with a Z boson produced in association with large missing transverse momentum at the LHC is presented. The search is based on the 2016 data sample of proton-proton collisions recorded with the CMS experiment at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). The results of this search are interpreted in terms of a simplified model of dark matter production via spin-0 or spin-1 mediators, a scenario with a standard-model-like Higgs boson produced in association with the Z boson and decaying invisibly, a model of unparticle production, and a model with large extra spatial dimensions. No significant deviations from the background expectations are found, and limits are set on relevant model parameters, significantly extending the results previously achieved in this channel.Peer reviewe

    Search for new physics in events with a leptonically decaying Z boson and a large transverse momentum imbalance in proton-proton collisions at root s=13 TeV

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    A search for new physics in events with a Z boson produced in association with large missing transverse momentum at the LHC is presented. The search is based on the 2016 data sample of proton-proton collisions recorded with the CMS experiment at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). The results of this search are interpreted in terms of a simplified model of dark matter production via spin-0 or spin-1 mediators, a scenario with a standard-model-like Higgs boson produced in association with the Z boson and decaying invisibly, a model of unparticle production, and a model with large extra spatial dimensions. No significant deviations from the background expectations are found, and limits are set on relevant model parameters, significantly extending the results previously achieved in this channel

    Measurement of neutral strange particle production in the underlying event in proton-proton collisions at root s=7 TeV

    No full text
    Measurements are presented of the production of primary K-S(0) and Lambda particles in proton-proton collisions at root s = 7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar transverse momentum sum of K-S(0) and Lambda particles measured at pseudorapidities vertical bar eta vertical bar &lt; 2 rise with increasing charged-particle jet p(T) in the range 1-10 GeV/c and saturate in the region 10-50 GeV/c. The rise and saturation of the strange-particle yields and transverse momentum sums in the underlying event are similar to those observed for inclusive charged particles, which confirms the impact-parameter picture of multiple parton interactions. The results are compared to recent tunes of the PYTHIA Monte Carlo event generator. The PYTHIA simulations underestimate the data by 15%-30% for K-S(0) mesons and by about 50% for Lambda baryons, a deficit similar to that observed for the inclusive strange-particle production in non-single-diffractive proton-proton collisions. The constant strange-to charged-particle activity ratios with respect to the leading jet p(T) and similar trends for mesons and baryons indicate that the multiparton-interaction dynamics is decoupled from parton hadronization, which occurs at a later stage

    Search for a very light NMSSM Higgs boson produced in decays of the 125 GeV scalar boson and decaying into tau leptons in pp collisions at root 8=TeV

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    A search for a very light Higgs boson decaying into a pair of tau leptons is presented within the framework of the next-to-minimal supersymmetric standard model. This search is based on a data set corresponding to an integrated luminosity of 19.7 fb(-1) of proton-proton collisions collected by the CMS experiment at a centre-of-mass energy of 8 TeV. The signal is defined by the production of either of the two lightest scalars, h(1) or h(2), via gluon-gluon fusion and subsequent decay into a pair of the lightest Higgs bosons, a(1) or h(1). The h(1) or h(2) boson is identified with the observed state at a mass of 125 GeV. The analysis searches for decays of the a(1) (h(1)) states into pairs of tau leptons and covers a mass range for the a(1) (h(1)) boson of 4 to 8 GeV. The search reveals no significant excess in data above standard model background expectations, and an upper limit is set on the signal production cross section times branching fraction as a function of the a(1) (h(1)) boson mass. The 95% confidence level limit ranges from 4.5 pb at m(a1) (m(h1)) = 8 GeV to 10.3 pb at m(a1) (m(h1)) = 5 GeV

    Pseudorapidity distribution of charged hadrons in proton-proton collisions at <tex>\sqrt{s}$</tex>=13TeV

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    Measurement of neutral strange particle production in the underlying event in proton-proton collisions at root s=7 TeV

    No full text
    Measurements are presented of the production of primary K-S(0) and Lambda particles in proton-proton collisions at root s = 7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar transverse momentum sum of K-S(0) and Lambda particles measured at pseudorapidities vertical bar eta vertical bar < 2 rise with increasing charged-particle jet p(T) in the range 1-10 GeV/c and saturate in the region 10-50 GeV/c. The rise and saturation of the strange-particle yields and transverse momentum sums in the underlying event are similar to those observed for inclusive charged particles, which confirms the impact-parameter picture of multiple parton interactions. The results are compared to recent tunes of the PYTHIA Monte Carlo event generator. The PYTHIA simulations underestimate the data by 15%-30% for K-S(0) mesons and by about 50% for Lambda baryons, a deficit similar to that observed for the inclusive strange-particle production in non-single-diffractive proton-proton collisions. The constant strange-to charged-particle activity ratios with respect to the leading jet p(T) and similar trends for mesons and baryons indicate that the multiparton-interaction dynamics is decoupled from parton hadronization, which occurs at a later stage

    Search for new physics in events with a leptonically decaying Z boson and a large transverse momentum imbalance in proton-proton collisions at <tex>\sqrt{s}$</tex>=13 TeV

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    Search for a very light NMSSM Higgs boson produced in decays of the 125 GeV scalar boson and decaying into tau leptons in pp collisions at <tex>\sqrt{s}$</tex> =8TeV

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