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  1. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(4):291.
    PMID: 31007582 DOI: 10.1140/epjc/s10052-018-5740-1
    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


    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.
  2. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(4):287.
    PMID: 31007580 DOI: 10.1140/epjc/s10052-018-5752-x
    A study of the associated production of a
    Z
    boson and a charm quark jet (

    Z
    +
    c

    ), and a comparison to production with a
    b
    quark jet (

    Z
    +
    b

    ), in

    p
    p

    collisions at a centre-of-mass energy of 8


    TeV

    are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7



    fb

    -
    1



    , collected with the CMS detector at the CERN LHC. The
    Z
    boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of
    c
    or
    b
    flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with


    p

    T



    >
    20

    GeV

    ,



    |


    η



    |


    <
    2.1

    ,

    71
    <

    m





    <
    111

    GeV

    , and heavy flavour jets with


    p

    T

    jet

    >
    25

    GeV

    and



    |


    η
    jet


    |


    <
    2.5

    . The

    Z
    +
    c

    production cross section is measured to be

    σ

    (
    p
    p

    Z
    +
    c
    +
    X
    )

    B

    (
    Z



    +



    -

    )

    =
    8.8
    ±
    0.5

    (stat)
    ±
    0.6

    (syst)

    pb

    . The ratio of the

    Z
    +
    c

    and

    Z
    +
    b

    production cross sections is measured to be

    σ
    (
    p
    p

    Z
    +
    c
    +
    X
    )
    /
    σ
    (
    p
    p

    Z
    +
    b
    +
    X
    )
    =
    2.0
    ±
    0.2

    (stat)
    ±
    0.2

    (syst)

    . The

    Z
    +
    c

    production cross section and the cross section ratio are also measured as a function of the transverse momentum of the
    Z
    boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.
  3. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(3):280.
    PMID: 31007587 DOI: 10.1140/epjc/s10052-019-6730-7
    A search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks is performed in proton-proton collisions at a center-of-mass energy of 13



    Te



    collected with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 35.9



    fb

    -
    1



    . The signal is characterized by a large missing transverse momentum recoiling against a bottom quark-antiquark system that has a large Lorentz boost. The number of events observed in the data is consistent with the standard model background prediction. Results are interpreted in terms of limits both on parameters of the type-2 two-Higgs doublet model extended by an additional light pseudoscalar boson
    a
    (2HDM+
    a
    ) and on parameters of a baryonic


    Z

    '

    simplified model. The 2HDM+
    a
    model is tested experimentally for the first time. For the baryonic


    Z

    '

    model, the presented results constitute the most stringent constraints to date.
  4. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(4):305.
    PMID: 31007588 DOI: 10.1140/epjc/s10052-019-6800-x
    A search is presented for resonant production of second-generation sleptons (


    μ
    ~

    L

    ,


    ν
    ~

    μ

    ) via the R-parity-violating coupling

    λ
    211
    '

    to quarks, in events with two same-sign muons and at least two jets in the final state. The smuon (muon sneutrino) is expected to decay into a muon and a neutralino (chargino), which will then decay into a second muon and at least two jets. The analysis is based on the 2016 data set of proton-proton collisions at


    s

    =
    13

    TeV

    recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9



    fb

    -
    1



    . No significant deviation is observed with respect to standard model expectations. Upper limits on cross sections, ranging from 0.24 to 730


    fb

    , are derived in the context of two simplified models representing the dominant signal contributions leading to a same-sign muon pair. The cross section limits are translated into coupling limits for a modified constrained minimal supersymmetric model with

    λ
    211
    '

    as the only nonzero R-parity violating coupling. The results significantly extend restrictions of the parameter space compared with previous searches for similar models.
  5. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys. Rev. Lett., 2019 Jan 11;122(1):011803.
    PMID: 31012697 DOI: 10.1103/PhysRevLett.122.011803
    A search is performed for dark matter particles produced in association with a top quark pair in proton-proton collisions at sqrt[s]=13  TeV. The data correspond to an integrated luminosity of 35.9  fb^{-1} recorded by the CMS detector at the LHC. No significant excess over the standard model expectation is observed. The results are interpreted using simplified models of dark matter production via spin-0 mediators that couple to dark matter particles and to standard model quarks, providing constraints on the coupling strength between the mediator and the quarks. These are the most stringent collider limits to date for scalar mediators, and the most stringent for pseudoscalar mediators at low masses.
  6. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, Brandstetter J, et al.
    Phys. Rev. Lett., 2019 Apr 05;122(13):132001.
    PMID: 31012626 DOI: 10.1103/PhysRevLett.122.132001
    Signals consistent with the B_{c}^{+}(2S) and B_{c}^{*+}(2S) states are observed in proton-proton collisions at sqrt[s]=13  TeV, in an event sample corresponding to an integrated luminosity of 143  fb^{-1}, collected by the CMS experiment during the 2015-2018 LHC running periods. These excited b[over ¯]c states are observed in the B_{c}^{+}π^{+}π^{-} invariant mass spectrum, with the ground state B_{c}^{+} reconstructed through its decay to J/ψπ^{+}. The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1±1.5(stat)±0.7(syst)  MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the B_{c}^{+}(2S) meson is measured to be 6871.0±1.2(stat)±0.8(syst)±0.8(B_{c}^{+})  MeV, where the last term corresponds to the uncertainty in the world-average B_{c}^{+} mass.
  7. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys. Rev. Lett., 2019 Apr 05;122(13):132003.
    PMID: 31012605 DOI: 10.1103/PhysRevLett.122.132003
    The observation of single top quark production in association with a Z boson and a quark (tZq) is reported. Events from proton-proton collisions at a center-of-mass energy of 13 TeV containing three charged leptons (either electrons or muons) and at least two jets are analyzed. The data were collected with the CMS detector in 2016 and 2017 and correspond to an integrated luminosity of 77.4fb^{-1}. The increased integrated luminosity, a multivariate lepton identification, and a redesigned analysis strategy improve significantly the sensitivity of the analysis compared to previous searches for tZq production. The tZq signal is observed with a significance well over 5 standard deviations. The measured tZq production cross section is σ(pp→tZq→tℓ^{+}ℓ^{-}q)=111±13(stat)_{-9}^{+11}(syst)  fb, for dilepton invariant masses above 30 GeV, in agreement with the standard model expectation.
  8. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys. Rev. Lett., 2019 Mar 29;122(12):121803.
    PMID: 30978057 DOI: 10.1103/PhysRevLett.122.121803
    This Letter describes a search for Higgs boson pair production using the combined results from four final states: bbγγ, bbττ, bbbb, and bbVV, where V represents a W or Z boson. The search is performed using data collected in 2016 by the CMS experiment from LHC proton-proton collisions at sqrt[s]=13  TeV, corresponding to an integrated luminosity of 35.9  fb^{-1}. Limits are set on the Higgs boson pair production cross section. A 95% confidence level observed (expected) upper limit on the nonresonant production cross section is set at 22.2 (12.8) times the standard model value. A search for narrow resonances decaying to Higgs boson pairs is also performed in the mass range 250-3000 GeV. No evidence for a signal is observed, and upper limits are set on the resonance production cross section.
  9. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(4):313.
    PMID: 31031568 DOI: 10.1140/epjc/s10052-019-6788-2
    A top quark mass measurement is performed using

    35.9



    fb

    -
    1




    of LHC proton-proton collision data collected with the CMS detector at


    s

    =
    13

    TeV

    . The measurement uses the

    t

    t
    ¯


    all-jets final state. A kinematic fit is performed to reconstruct the decay of the

    t

    t
    ¯


     system and suppress the multijet background. Using the ideogram method, the top quark mass (

    m
    t

    ) is determined, simultaneously constraining an additional jet energy scale factor (
    JSF
    ). The resulting value of


    m
    t

    =
    172.34
    ±
    0.20

    (stat+JSF)
    ±
    0.70

    (syst)

    GeV

    is in good agreement with previous measurements. In addition, a combined measurement that uses the

    t

    t
    ¯


    lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an

    m
    t

    measurement of

    172.26
    ±
    0.07

    (stat+JSF)
    ±
    0.61

    (syst)

    GeV

    . This is the first combined

    m
    t

    extraction from the lepton+jets and all-jets channels through a single likelihood function.
  10. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys. Rev. Lett., 2019 Apr 19;122(15):151802.
    PMID: 31050519 DOI: 10.1103/PhysRevLett.122.151802
    For the first time, a search for the rare decay of the W boson to three charged pions has been performed. Proton-proton collision data recorded by the CMS experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 77.3  fb^{-1}, have been analyzed. No significant excess is observed above the background expectation. An upper limit of 1.01×10^{-6} is set at 95% confidence level on the branching fraction of the W boson to three charged pions. This provides a strong motivation for theoretical calculations of this branching fraction.
  11. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys. Rev. Lett., 2019 Apr 19;122(15):152001.
    PMID: 31050516 DOI: 10.1103/PhysRevLett.122.152001
    The modification of jet shapes in Pb-Pb collisions, relative to those in pp collisions, is studied for jets associated with an isolated photon. The data were collected with the CMS detector at the LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Jet shapes are constructed from charged particles with track transverse momenta (p_{T}) above 1  GeV/c in annuli around the axes of jets with p_{T}^{jet}>30  GeV/c associated with an isolated photon with p_{T}^{γ}>60  GeV/c. The jet shape distributions are consistent between peripheral Pb-Pb and pp collisions, but are modified for more central Pb-Pb collisions. In these central Pb-Pb events, a larger fraction of the jet momentum is observed at larger distances from the jet axis compared to pp, reflecting the interaction between the partonic medium created in heavy ion collisions and the traversing partons.
  12. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, Brandstetter J, et al.
    Phys. Rev. Lett., 2019 Sep 27;123(13):131802.
    PMID: 31697516 DOI: 10.1103/PhysRevLett.123.131802
    A search for a light charged Higgs boson (H^{+}) decaying to a W boson and a CP-odd Higgs boson (A) in final states with eμμ or μμμ is performed using data from pp collisions at sqrt[s]=13  TeV, recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9  fb^{-1}. In this search, it is assumed that the H^{+} boson is produced in decays of top quarks, and the A boson decays to two oppositely charged muons. The presence of signals for H^{+} boson masses between 100 and 160 GeV and A boson masses between 15 and 75 GeV is investigated. No evidence for the production of the H^{+} boson is found. Upper limits at 95% confidence level are obtained on the combined branching fraction for the decay chain, t→bH^{+}→bW^{+}A→bW^{+}μ^{+}μ^{-}, of 1.9×10^{-6} to 8.6×10^{-6}, depending on the masses of the H^{+} and A bosons. These are the first limits for these decay modes of the H^{+} and A bosons.
  13. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(9):773.
    PMID: 31713548 DOI: 10.1140/epjc/s10052-019-7276-4
    A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta,

    Δ

    ϕ
    12


    , is presented. The measurement considers events where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of

    13


    Te



    and corresponding to an integrated luminosity of

    35.9



    fb

    -
    1




    are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region


    177


    <
    Δ

    ϕ
    12

    <

    180



    . The 2- and 3-jet measurements are not simultaneously described by any of models.
  14. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(2):140.
    PMID: 31265001 DOI: 10.1140/epjc/s10052-018-5607-5
    A search for standard model production of four top quarks (

    t

    t
    ¯

    t

    t
    ¯


    ) is reported using events containing at least three leptons (

    e
    ,
    μ

    ) or a same-sign lepton pair. The events are produced in proton-proton collisions at a center-of-mass energy of 13


    TeV

    at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9



    fb

    -
    1



    . Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the

    t

    t
    ¯

    t

    t
    ¯


    cross section is measured to be

    16
    .

    9

    -
    11.4


    +
    13.8






    fb

    , in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level.
  15. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(11):886.
    PMID: 31764915 DOI: 10.1140/epjc/s10052-019-7387-y
    A search for new physics in top quark production is performed in proton-proton collisions at

    13

    TeV

    . The data set corresponds to an integrated luminosity of

    35.9



    fb

    -
    1




    collected in 2016 with the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons), and
    b
    quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a
    W
    boson. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of effective field theory and constraints on the relevant effective couplings are set, one at a time, using a dedicated multivariate analysis. This analysis differs from previous searches for new physics in the top quark sector by explicitly separating

    t
    W

    from

    t


    t


    ¯



     events and exploiting the specific sensitivity of the

    t
    W

    process to new physics.
  16. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(5):421.
    PMID: 31178657 DOI: 10.1140/epjc/s10052-019-6909-y
    Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision data set recorded with the CMS detector in 2016 at


    s

    =
    13


    Te



    , corresponding to an integrated luminosity of 35.9



    fb

    -
    1



    . The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a
    W
    or
    Z
    boson, or a top quark-antiquark pair) and the following decay modes:

    H

    γ
    γ

    ,

    Z
    Z

    ,

    W
    W

    ,

    τ
    τ

    ,

    b
    b

    , and

    μ
    μ

    . Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be

    μ
    =
    1.17
    ±
    0.10

    , assuming a Higgs boson mass of

    125.09


    Ge



    . Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.
  17. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(4):364.
    PMID: 31180390 DOI: 10.1140/epjc/s10052-019-6855-8
    A search for the pair production of heavy vector-like partners
    T
    and
    B
    of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton-proton collisions at


    s

    =
    13


    Te



    . The data sample was collected in 2016 and corresponds to an integrated luminosity of 35.9



    fb

    -
    1



    . Final states studied for

    T

    T
    ¯


    production include those where one of the
    T
    quarks decays via

    T

    t
    Z

    and the other via

    T

    b
    W

    ,

    t
    Z

    , or

    t
    H

    , where
    H
    is a Higgs boson. For the

    B

    B
    ¯


    case, final states include those where one of the
    B
    quarks decays via

    B

    b
    Z

    and the other

    B

    t
    W

    ,

    b
    Z

    , or

    b
    H

    . Events with two oppositely charged electrons or muons, consistent with coming from the decay of a
    Z
    boson, and jets are investigated. The number of observed events is consistent with standard model background estimations. Lower limits at 95% confidence level are placed on the masses of the
    T
    and
    B
    quarks for a range of branching fractions. Assuming 100% branching fractions for

    T

    t
    Z

    , and

    B

    b
    Z

    ,
    T
    and
    B
    quark mass values below 1280 and 1130



    Ge



    , respectively, are excluded.
  18. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(5):444.
    PMID: 31265003 DOI: 10.1140/epjc/s10052-019-6926-x
    A search for supersymmetry is presented based on events with at least one photon, jets, and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of 13



    Te



    . The data correspond to an integrated luminosity of 35.9



    fb

    -
    1



    and were recorded at the LHC with the CMS detector in 2016. The analysis characterizes signal-like events by categorizing the data into various signal regions based on the number of jets, the number of
    b
    -tagged jets, and the missing transverse momentum. No significant excess of events is observed with respect to the expectations from standard model processes. Limits are placed on the gluino and top squark pair production cross sections using several simplified models of supersymmetric particle production with gauge-mediated supersymmetry breaking. Depending on the model and the mass of the next-to-lightest supersymmetric particle, the production of gluinos with masses as large as 2120



    Ge



    and the production of top squarks with masses as large as 1230



    Ge



    are excluded at 95% confidence level.
  19. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys. Rev. Lett., 2019 Jul 12;123(2):022001.
    PMID: 31386524 DOI: 10.1103/PhysRevLett.123.022001
    The transverse momentum spectra of D^{0} mesons from b hadron decays are measured at midrapidity (|y|<1) in pp and Pb-Pb collisions at a nucleon-nucleon center of mass energy of 5.02 TeV with the CMS detector at the LHC. The D^{0} mesons from b hadron decays are distinguished from prompt D^{0} mesons by their decay topologies. In Pb-Pb collisions, the B→D^{0} yield is found to be suppressed in the measured p_{T} range from 2 to 100  GeV/c as compared to pp collisions. The suppression is weaker than that of prompt D^{0} mesons and charged hadrons for p_{T} around 10  GeV/c. While theoretical calculations incorporating partonic energy loss in the quark-gluon plasma can successfully describe the measured B→D^{0} suppression at higher p_{T}, the data show an indication of larger suppression than the model predictions in the range of 2
  20. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(7):564.
    PMID: 31397444 DOI: 10.1140/epjc/s10052-019-7058-z
    A search is presented for a heavy pseudoscalar boson
    A
    decaying to a Z  boson and a Higgs boson with mass of 125


    GeV

    . In the final state considered, the Higgs boson decays to a bottom quark and antiquark, and the Z  boson decays either into a pair of electrons, muons, or neutrinos. The analysis is performed using a data sample corresponding to an integrated luminosity of 35.9



    fb

    -
    1



    collected in 2016 by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13



    Te



    . The data are found to be consistent with the background expectations. Exclusion limits are set in the context of two-Higgs-doublet models in the
    A
    boson mass range between 225 and 1000


    GeV

    .
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